EOS R SYSTEM
WHITE PAPER
A New Lens-Camera System
Written by Larry Thorpe, Canon U.S.A., Inc
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Abstract!! ! ! ! ! ! ! ! ! ! ! 1!
1.0 !!!!!!HISTORY!OF!THE!EOS!SYSTEM! ! ! ! ! ! ! ! 1!
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2.0 !!!!!!!EOS!SYSTEM!EXTENDS!TO!DIGITAL!CINEMA!! ! ! ! ! ! 2!
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3.0 !!!!!!!LIMITATIONS!OF!THE!CURRENT!EO S!SYSTEM! ! ! ! ! ! 4!
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4.0 !!!!!!!A!CHANGING!GLOBAL!MARKETPLACE! ! ! ! ! ! ! 4!
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5.0 !!!!!!!AN!IDEAL!LENS!CAMERA!SYSTEM! ! ! ! ! ! ! ! 5!
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6.0 !!!!!!!EXTENDING!LENS!DESIGN!OPTIONS! ! ! ! ! ! ! 5!
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7.0 !!!!!!!KEY!TO!A!NEW!GENERATION!OF!LENSES!—!NEW!LENS!MOUNT! ! ! ! 7!
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8.0 !!!!!!!DETAILS!OF!THE!NEW!CANON!RF!MOUNT! ! ! ! ! ! ! 8!
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9.0 !!!!!!CHALLENGE!OF!MANAGING!LENS!ABERRATIONS! ! ! ! ! ! 10!
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10.0 !NEW!CONCEPTS!UNDERLYING!RF!LENSES! ! ! ! ! ! ! 12!
10.1 !!!!!New!Feature!Unique!to!RF!Lenses! ! ! ! ! ! 12!
10.1.1 !!!!!Control!Ring! ! ! ! ! ! ! ! 12!!!!!!!!!!!!!!
10.1.2 !!!!!Aperture!Blade!Control!! ! ! ! ! ! 12!!!!!!!!!!!!!!!!
10.1.3 !!!!!Focus!Ring!Rotation!Direction!Change! ! ! ! ! 13!!!!!!!!!!!!!!!!
10.1.4 !!!!!Enhanced!Electronic!Communication!between!Lens!and!Camera!!!!!!!!!!!!!!!!!!!!!!!!13!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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11.0 !INTRO D U C T O R Y !F A MILY!OF!RF!LENSES! ! ! ! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!13!
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11.1 !!!!!!!!RF28-70mm!F2!L!USM!! ! ! ! !!!!!!!!!!!!!!!!! ! 14!
11.2 !!!!!!!!RF50mm!F1.2!L!USM! ! ! ! ! !!!!!!!!!!!!!!!!! ! 19!
11.3 !!!!!!!!RF24-105mm!F4!L!IS!USM!!!!!!!!!!!!!!!!!!! !!!!! ! ! ! ! 22!
11.4 !!!!!!!!RF35mm!F1.8!MACRO!IS!STM! ! ! ! ! !!!!!!!!!!!!!!!!! 27!
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12.0 !EF!LENS!MOUNT!ADAPTERS! ! ! ! ! ! ! ! 30!
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13.0 !EOS!R!LENS-CAMERA!SYSTEM! ! ! ! ! ! ! ! 32!
13.1 !!!!!!!!Enhanced!Image!Stabilization!System! ! ! ! ! ! 32!
13.2 !!!!!!!!Digital!Lens!Optimizer!(DLO)!System! ! ! ! ! ! 34!
13.3 !!!!!!!!Dual!Pixel!CMOS!AF!System! ! ! ! ! ! ! 36!
13.4 !!!!!!!!Comparison!of!EOS!R!lens-came ra!system!with!EF!lens!and!DSLR! ! ! 39!
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14.0 !!!!!!SUMMARY! ! ! ! ! ! ! ! ! ! 41!
Abstract&
The$Canon$EOS$ system$ is$ comprised$ of$ EF$lenses,$EF-S$lenses,$and$associated$cameras.$$This$system$is$
now$thirty$years$old.$$$It$remains$robust$and$innovative.$$$These $intercha n ge a b le $le n s-cameras$systems$
service$multiple$levels$of$the$global$imaging$marketplace$—$fro m $th e$h igh e st$p rofe ssio na l$le ve ls$to$the$
aspiring$new$ photographers$within$ the$ larger$ consumer$ base.$ $ $ But$ toda y,$ both$ still$ photog r a p h y $ and$
motion$imaging$are$branching$out$in$ multiple$directions$—$propelled$by$a$ m ovement$spawned$a$ decade$
ago$w ith$ the$arrival$ of$ the$hybrid$interchangeable$lens-came ra.$$Today,$even$ hig h $end$mov iemaking$and$
television$pro du ction $ q uite$ re ad ily$ inco rpo rate $Canon$ EOS$lenses$and$cameras$into$their$arsenal$of$image$
acquisition$tools.$Separately,$social$media$and$ diverse$w eb-based$ services$are$spawning$new$businesses$
and$creative$initiatives$in$still$and$motion$imaging.$$$
While$the$quest$for$more$resolution$remains,$the$pa st$decade$ ha s$also$seen$a$rapidly$growing$awareness$
of$other$dimensions$of$image$quality$—$ color$reproduction,$ dynamic$ range,$ and$ picture$ capture$rates.$$
Mirrorless$ cameras$have$emerged$and$have$a$growing$following.$ $Shooting$practices$are$unceasing$in$
their$diversity$and$inge nu ity.$$
Assimilating$all$of$these$movements$on$a$worldwide$scale$led$Canon$to$the$conclusion$that$a$juncture$has$
been$reached$where$new$flexibilities$were$imperative$to$expand$the$possibilities$of$the$Canon$EOS$system$
to$support$future$decades$of$both$still$an d$motion$imaging$—$in$a ll$of$their$manifesta tio n s .$$$Given$ that$
optics$is$ the$very$core$ of$ Canon$ led$ to$ a $ conclusio n $ that$ new$ lenses$ offering$ im p orta n t$ e nh an cements$
must$constitute$the$ spearhead$of$ this$initiative.$In$ turn,$this$ would$be$ predicated$ on$ the$ design$ of$ a$ new$
lens$mount$tha t$ w ou ld$ e m po w er$lens$dev elo p ments$to$be$take n $ t o $ n e w $levels.$$ $$Continuing$support$of$EF$
and$EF-S$lens es $w o u ld $b e $fa cto re d $in to $t he $n e w $s ys te m$design.$
This$ white$ paper$ will$ discuss$ in$ some$ detail$ the$ new$ lens$ mount$ design$ and$ its$ implications$ for$ an$
importa n t $ne w$generation $o f$le ns e s$a n d $ca meras.$
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1.0& HISTORY&OF&THE&CANON&EOS&SYSTEM&
In!198 7 !C a n o n ! lau n c h e d !a ! n ew!imaging! sy st e m ! th a t! tr an s fo r m e d ! th e !world!of!p h o to g ra p h ic !imaging.!Th e!
Canon! EO S! system! was! squarely! based! upon! an! innovative! new! lens! m ount! that! had! the! following!
attributes:!
1. Large!54mm!inner!diameter!mount!—!term ed!the!EF!mount!
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2. Flange!back!distance!o f!44mm!
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3. Flexible !e lec tro n ic !co mmunicatio n!b e tween!lens!an d!c a m e ra.!!
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4. Large!diameter!mount!opened!broad!options!in!lens!design.!!!!
It! allo wed! larg e ! apertu r e! lens! design s ! that! main ta in e d ! high! optica l! perfo rmance.! Central! to! this!
design!was! the! total! absence! of! mechanical!linkages! between! the!moving!parts!within! the! lense s!
and!the!camera.!
1!
All!operational!functions!were!supported!by!the!electrical!communication!between!the!lens!and!camera.!!
This! comm unication! allowed! focusing! motors! to! be! optimally! positioned! within! each! individual! lens!
design,! which! supported! fast! auto! focus! systems.! ! The! aperture! control! was! also! electronic! which!
supported! auto-aperture! functionalities.! ! In ! the! e n s u in g ! decades! these! core! design! strategies!
empowered!a! progressive!imag in g ! evo lu tio n ! tha t! witne ssed ! the ! em ergence!of!an! extraordinary!broad!
range!o f! zoo m ! a nd ! p rim e! le nse s!that!were!flanked!initially ! by! SLR!35mm! film!cameras!and!ultimately!the!
arrival!of!the!all-digital!DSLR!camera!in!the!early!21
st
!century.!
In!1995 !th e !fir st!lens!with!built-in!image !sta b iliz at ion !s ys te m!became!possible!based!upon!that!electronic!
communication! (the! EF75-300mm! f/4-5.6! IS! USM).! ! The! lens-cam era! movem ents! detected! within! the!
lens! itself! are! processed! and! control! signals! generated! that! actuate! correction! optics! within! the! lens.!!
That! large! diameter! mount! and! the! electronic! communication! continue! to! empower! new! features! in!
both!lens!and!cam era!to!this!day.!!!And!the!paced!expansion!of!EF!lenses!and!cameras!over!the!years!
speaks!a!great!deal!about!the!success!of!this!remarkable!design!strategy.!
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Figure& 1&&&&&&&Three$ decades$of$the$ Canon$ EOS$ system$has$ seen$ an $ impressive$ evolution$ of$lenses$and$
cameras$that$presently$serve$a$worldwide$market$at$many$levels$
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2.0& &&&CANON&EOS&SYSTEM&EXTENDS&TO&DIGITAL&CINEMA&
Today’s!world! production! community!—! both!theatrical!motion! picture!and! episodic!television!—!will!
utilize! all! m anner! of! lens-camera! combinations! to! achieve! their! creative! aspira tions ! an d! m e et! th eir!
production! budgets.! ! Major! movies! have! been ! produced! that! incorporated! DSLR’s! coup led! to! digital!
cinema!lenses!and!high-end!digital!cinema!cameras!using!EF!lenses.!!
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2!
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Figure&2& The$global$production$communities$freely$“mix$‘n$match”$le n se s$a n d $ca meras$
In! 2011! Canon! leveraged! the! vast! accumulation! of! experiences! in! the! broadcast! television! optics!
business!and! that! of! the! now! firmly!established! Canon! EOS! system! to! enter! the! digital!cinema! world!
with!a!family!of!high-end!professional!digital!cinema!lenses!(both!prim es!and !zoo ms)!an d!cam eras! —!the!
Canon! Cinema!EOS!system.! !This!system! was!designed! to!utilize! the!EF!mount! —!while!also!offering!the!
option! of! the! established! cinematography! PL! m ount! on! the! higher! end! products! within! this! family.!!!
While!distinctly!different!in! their!respective!target!markets!both! lens-camera!families!benefited!greatly!
from! the! shared! techn o logie s.! ! ! ! T his! syste m izatio n! offere d! the! prod u ction ! world ! great! flexibilities! in!
combining!A-Cameras!with!a!range!of!choices!in!B-camera!and!C-camera!options.!
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Figure&3&&&&&Sug gesting$the$technological$ o verlap$between$the$Canon$EOS$still$ photography$systems$(left$
and$center)$and$the$Canon$Cinema$EOS$motion$imaging$system$on$the$right$
3!
3.0&&&&&&&&&&&LIMITATIONS&OF&THE&CURRENT&EOS&SYSTEM&!
Assessing!the!current!EOS! system! in!the! context!of! future!considerations!exposes!some! limitations!as!
follows:!
1. Insufficie n t! flexibilities ! in! m o u nt!diame te r ! and! back! f o cu s ! distance! to! accommodate! all! of!
the!increasingly!diverse!requirements!in!zoom!and!prime!lenses!
!
2. Limited!speed!of!the!electronic!communication!between!lens!and!camera!
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3. Limited! electronic! chan nels! between! lens! and! cam era! to! accom mo date! new! o perational!
aspirations!!
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4. Constraints!in!sensor-based!AF!operational!capabilities!
Collectively,! these! considerations! make! a! compelling! case! for! a! m ore! encompassing! approach! to! the!
intercha n ge a b le! lens-cam era! system ! going! forward.! ! ! A! ne w! lens! system ! is! pivotal! to! form! an!
underpinning!core!to!the!new!EOS!R!system.!
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4.0& &&&&&&&&A&CHANGING&GLOBAL&MARKETPLACE&
Digital! imaging! has! been! with! us! for! almost! a! quarter! century.! ! But,! the! past! decade! has! seen!
extraordinary!advances! in! both! image! performance! and! creative! flexibilities! offered! b y! contemporary!
lenses!a nd!cameras.!!The!former! lines!separating!still!and!motion! imaging!are!blurred,!image!resolution!
has!soared,! and!end!user!demands!for! m ore! operational! empowerments! are!unceasing.!! Applications!of!
intercha n ge a b le!le n s - ca me ra!systems!continually!broaden.!
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4!
5.0& &&&&&&&AN&IDEAL&LENS-CAMERA&SYSTEM!!
Three! decades! after! the! debut! of! the! Canon! EOS! system! Canon ! b elieves! that! new! and! broadening!
marketplace! dynamics! require! an! extension! to! the! original! design! premise! of! the! EF! interchangeable!
lens-cam era!system .!An!ideal!lens-camera!system!inten d e d !fo r! fu tu re !y ea rs !in !imaging!would!include!the!
following! co ntem porary!considerations:!
1. Emerging!popularity!of!the!full!frame!image!sensor!
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2. Anticipated!progressive!elevation!of!sensor!resolution!
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3. Quest!for!higher!exposure!ranges!!
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4. Increasing! diversity! and! sophistication! of! end-users! seekin g ! extended! operational!
functionalities !
All!of!these!considerations!bear!directly!on!the!lens!and!lens!mount!designs.!
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6.0& &&&&&&EXTENDING&LENS&DESIGN&OPTIONS&
There! continues! to ! be! an! inexorable! growth! in! the! needs! and! aspirations! of! the! m ultiple! creative!
communities!presently!engaged! in!both!still!and!motion!imaging.!!!Widely! differing!needs! in! zooms!and!
primes! encompass! a! spectrum! of! optical! performances,! size/weight! considerations,! a nd! operational!
features!—!often!requiring!a!pragmatic!balance!between!the se!three!central!specifications!—!Figure!4.!!!
Long!focal!ranges!combined!w ith!a!wide!ap erture!—!as!required!for!sports!coverage!—!might!militate!
against!achievement!of!the!highest!optical!performance.!!!Lenses!intended!for!p ortraiture!might!assign!
the! top! prio rity! to ! ov era ll! optica l! pe rform a nc e! s pec ification s! —! perhaps! at! a! cost! of! some! limit! to!
aperture!and!maybe!size!and!weight.!!!The!variations!in!diverse!sh o o tin g!r eq u ire ments!are!end le ss .!
!!!!!!!!!!!!!!!!!!!!!!!! !
!Figure&4! The$totality$of$lens$design$entails$many$parameters$that$bear$upon$three$key$criteria$
If!the! area!o f!the!triangle!in!Figure!4! reflects! all! of! the! op tica l,! optom e ch an ical,! and! electronic!design!
parameters! available! to!the!lens!designers,!then!m aximizing!that! area!offers!greater!options!in!favoring!
certain!specifications,!or!alternatively,!optimizing!the!balance!between!the!three!core!specifications.!
5!
In!that!context,!seekin g !the!id ea l!le ns !fo r!a!give n!sh oo ting !ap plica tion !must!envisage!broadening!
flexibilities!in!optical!and!system!developments!according!to!the!following:!
1. Highe r! Optical! Performance! —! to! a cco m m o date ! multiple! future! e nh an ce m en ts! in! cam e ra!
performance!
!
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2. !Increa se d !optical!speed!—!for!specific!lense s!
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3. Enhanced! Operational! Specifications! —!!such ! as! focal! lengt h! ran ge s,! maximum!aperture,! and!
their!controls!
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4. Meeting! demands! in! Size! and! Weight! Specifications! —! which! can! be! critically! important! to!
certain!forms!of!shooting!
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The! ideal! lens! for! a! g iven ! shooting! application ! typically! se ek s! optimizatio n! of! on e! of! the ! three!
specifications,! generally! accompanied! by! a ! desire! to! also! e levate! the! priority! of! a! second! of! these!
specifications!—!as!suggested!in!Figure!5.!!!!Note!that!the!area!of!the!triangle!remains!cons ta nt !—!but!
the!increased!numb er!of!design!parame ters!offers!new!flexibilities!to!achieve!these!higher!design!goals.!!!
For! other! lens! designs,! there! are! also! more! options! available! to! support! a! more! favorable! balance!
between!the!three!specifications.!
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Figure&5&& Illustrating$the$d iversity$in$lens$designs$required$to$meet$con tem p ora ry$im a gin g$n eed s$
Over!the!decades!the!Canon!EOS!EF!lens!designs!have!supported!reasonable!flexibility!in!m a na g ing !o ft en !
conflicting!requ irem e nts!—!primarily! b ec au se!of!the!large!54! m m !mount.! !On!th e !other!h a n d,!the!lo ng e r!
44mm!flange!back!distance!(d istan ce!from!a!reference!p oin t! o n!the!lens! mount!to! th e!image!se ns or!)has!
hampered!certain!d egrees!of!freedom!in! some! lens!designs.!!That!space! between!the!final!lens!element!
and! the! im ag e ! sensor! (especially ! in! the ! case! o f! the! large! full! frame! image! sensor )! is! inva lu ab le ! to!
achieving! optimization! of! the! projected! image! performance.!!Accordingly,! central! to! achieving!
extensions!in!lens!design!options!is!a!radical!red e sig n !o f!th e !len s !mount.!
6!
7.0&& &&KEY&TO&NEW&LENS&GENERATION&—&NEW&LENS&MOUNT&
Central!to!the!effective!implementation!of!the!strategy!to!extend!the!p ote ntial!o f!the !EO S!sy stem !fo r!th e!
future! is! a! new ! lens! m ount.! ! Canon!has! developed! a! mount! that! holds!high!promise! of! sustaining!far!
more!flexible!lens!designs!over!the!long!term!—!th e!ne w !RF!mount.!
!
! !!!!!!!!!!!!!!!!!!!!!!!!!!!!! !
Figure&6& The$new$lens$mount$is$designed$to$empower$ new$ flexibilities$in$le ns $ design$ and $ a$new$
generation$of$mirrorless$cameras$
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Considerations&that&guided&the&new&lens&mount&design:&
1. Totally!new!mount!—!but!one!that!retains!the!large!54!mm!in n er !diameter!of!the!EF!m ount!
!
2. Accommodate!current!Canon!EOS!image!sensor!sizes!up!to!Full!Frame !36 mm!x!24m m!!
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3. Leverage!the!shorter!20mm! flange! back! distance!of!the!Mirrorless! (ML)!system!to !su ppo rt!new!
optical!designs!
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4. Significant!elevation!of!the!electronic!communication!in!the!new !interchangeable!lens-camera!
system!—!!increasing!!th e!n um b er!o f!con tact!p ins!from !e ight!(curre nt!E F)!to !twe lve!!
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5. Accommodation!of!existing!(and!new)!EF!lenses!—!with!virtually!no!performance!compromises!
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7!
8.0& &&&&&&DETAILS&OF&THE&NEW&CANON&RF&MOUNT&
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Figure&7&&&&&&&&&&Showing$new$RF$mount$(on$the$right)$side$by$side$with$the$existing$EF$mount$(on$the$left)$
RF!mount!is !a!new!mount!that! m aintains!the!advantages!of!a! fu lly!electronic!large -diameter!EF!m ounts!
while! additionally!offering!an!optimal!diameter,!flange!back,!and!back!focus!to!more!fully!capitalize!on!
optical!characteristics!of!a!full-frame!mirrorles s!syste m s .!
Like! the! EF! mo unt,! a! 3-tab! bayonet! mount! is! used! in! the! RF! mount.! However,! to! prevent! incorrect!
attachment,!bayonet!tabs!are!in!different! positions!than!they!are! on !th e!EF! mo unts.!For!this!reason,!EF!
lenses!cann o t!be!attac he d !direct ly.!In!use,!the!new! RF!mount!also!resembles!existing!EF!mounts.!Lenses!
are!rotated!to!an! angle! of! 60°!for! attachment! or!rem oval,!and! the! lens!lock! pin! is!in! the! same! position!as!
on! an! EF! mount! (at! th e! 3! o’clock! position,! as! viewed! from ! the! front! of! the! camera),! with! the! same!
amount!of!protrusion!and!movement.!!
8!
The!reduction!from!a!44mm!flange!back!distance!in!the!EF!mount!system!to!the!20!mm!of!the!new!RF!
mount!system!opens!important!additional!degrees!of!freedom!in!lens!designs.!!The!pivotal!innovation!
offered!by!this! short!distance,!combined!with! the! large!54!mm!diameter! RF!mount! —!is!the!freedom!to!
deploy!large!diameter!optical!elements! at! the!very!rear!of! the! lens! and! closer!to! the !large! im ag e!sensor.!!
This!adds!new!optimization!capabilities!to!the!lens-camera!imaging!interface.!
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Figure&8!!! The$ new $ lens$ mount$ significantly$ expands$ the$ deg rees$ of$ freedom$ in$ mo bilizing$ the$
multiple$variables$in$high-end$le n s$d e sig n $ to $im plem e nt$a $far$grea ter$ra ng e$of$zo om $a nd $prim e$len ses!
!
The!new!RF!mount!makes!possible!greater!lens!design!flexibilities:!
1. Large!diameter!rear!lens!elements!that!are!mu ch!closer!to!the!full!frame!image !sensor!—!
enhancing! overall! optical! performa nce ! (in! particular,! tighter! contro l! over! optical!
aberrations!at!image!extremities)!!
!
2. Lenses! having!the!same! s pecif ica tio n s!for!focal!length!and!maximu m!ape rt ur e!as!current!EF!
mount!lenses—but! having$ significantly$ higher$ image$ quality! —! within! the! same! size! and!
weight!
!
3. High!o p tic al!p e rfo rmance,!large !a p e r tu r e !(F 1.2)!prime!lense s!f or !fu ll!fra m e !c ameras!
!
4. Zoom! lenses! of! higher! brightness! with! constant! aperture! over! their! focal! ranges! —!while!
still!modest!in!size!and!weight!
The!following!section!is!intende d!to!co nv ey!the !critical!impo rtan ce !of!back !focus !distan ce!an d!rea r!lens!
diameter!on!the!overall!optical!performance!of!a!given!lens.!
9!
9.0& THE&CHALLENGE&OF&MANAGING&LENS&ABERRATIONS&
Optical! aberrations! are! an! inescapable! reality! of! each! and! every! element! within! all! lenses.! ! The! well-
known!Seidel!monochromatic!aberrations are!image!defects!associated!with!the!fundamental!behavior!
of!light!rays—of!all!w avelengths!—!passing!through!a!lens!element.!!These!m onochromatic!aberrations!
include! sp herical$ aberration,$ coma,$ astigmatism ,$ curvature$ of$ field$ and$ geometric$ distortion.!!!
Collectively,!they!are!often!termed!the!“defocusing!distortions”!because!they!cumulatively!conspire!to!
impair!image!sharpn es s!( es p ec ia lly!a s!a !le n s!iris !se t tin g!a p p ro a ches!maximum!aperture).
!
In!addition!t o !monoch r o m a t ic!aberrations,! the re!are!additional!aberrations!associated!with!colored!light!
that! are! wavelength-dependent.! !!Different! w avelengths! of! light! enc o u n te r! a! diffe ren t ! index! of!
refraction!w ithin !a !g iven !o p tical!material,!referred!to!as!dispersion.!!!These!are!technically!described! by!
two!aberra tions :!(a)!!Longitudinal$chromatic$aberration$(different!focus!plane!for!c on stitu en t!co lors)! th at!
produce! an! unwanted! colored! flare;! ! and! (b)! Lateral$ chromatic$ aberration$ (because! magnification! of!
differen t! wavelen g th ! rays! vary! they! cau s e ! an! associated! variation! in! the! lateral! m agnification! that!
producing!an!effective!color!misregistration!in!th e !reco rd ed !video !or!still!im age).!!
!
Light! rays! passing! thro ugh ! th e! ce nte r! of! a! m u lti-elem ent! lens! will! exhibit! a! modest! degree! of! these!
aberrations.! !How ever,!as!light! rays!from!the! extremities! of!a! framed! scene!enter! the! lens! at!increasing!
angles! and! are! ultimately! focused! on! the! extremities! of! the! CMOS! image! sensor! image! plane,! the!
aberrations!can!all!rapidly!increase.!!The!m ore!acute!the!an gle!of!those!rays!being!projected!on !to!the!
sensor! —! the! greater! the! level! of! aberrations.! !! For! a! large! image! se nso r! like! Full! F ram e! this! pose s! a!
particular!challenge!to!the!lens!—!especially!when!the!corners!of!the!image!contain!high!detail.!!!!
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Figure&9!!!!!!Concept$of$a$hypothetical$len s$im a g in g$a$h igh ly $de ta ile d $scen e $—$and$the$importance$ of$the$
back$focus$distance$and$rear$lens$diameter$on$the$angle$of$a$ray$bundle$projecting$onto$the$corners$of$
the$image$sen so r$
10!
Two!key! dimensions!play!a!significant!role!in!the!quality!of!the!final! imag e! projec ted ! on! to! the!image!
sensor!—!they!are!th e! back!focus!distance!and!the!diameter!of!the!final!lens!element.!!!!Figure!9!is!a !
simplistic!illustration!of! the ir! cum ulative! effect! on ! the ! ang le! of! th e! ray!bundle!landing! o n!the!extremities!
of! the!image!senso r.!! T h e !c olo re d !c irc les !id e n tify !ra y !b u n d les !a ffe c tin g!image!perfo rmance!in!the !image!
central!zone!(red)!and!in!the!image!extremities!(blue).!
!
As!the!refractive!in de x ,!or!“bending”!power!of!the!lens!increases,!various!aberrations!tend!to!increase!
easily.!
!
If! th e! rear! lens! is! larg e r,! ray! bu n dles ! can! be! projected! more! gently! to! the! larger! image ! sensor ! and!
suppression!of!the !occurrence!of!various!aberrations!can!be !made.!On!the!other!hand,!the!smaller!the!
rear!le ns! is ,! it! is!necess a ry! th at ! the!refraction ! of! th e! ray! have! a! more! acute! angle!to!the! larger! image!
sensor!by!stronger!refractive!power!of!the!lens,!which!can!le a d !to!more!var io u s !a b e rr a tio n s .!
!
The! criticality! of! the! back! focus! distance! is! simplistically! illustrated! in! Figure! 10.! ! ! The! top! image!
simulates! a! lens! having! a! long! back! fo cus! distance! —! such! a s! exists! in! the! current! Canon! EOS! EF! lens!
system.!!!Many! d esign!strategies!are!mo bilized! for!the!many!different!types!o f! zoo m ! an d! p rime!lenses!in!
this! family! of! lenses! to! c ou nte ract! the! e ffect! of! aberrations.! ! One! k e y! strategy! is! to! us e! a! large ! le n s!
element!in!the! front! of! the! lens! system! to! more!independently!and! gently! manage!the!degree!of!the!
angle!of!the!emerging!light! ray!bundle!projected!on!to!the!image!sensor.!!This!generally!will! exten d!the!
length!o f!th e !o ve ra ll!o p tic al!s ys te m.!!!
If,!ho wever,!the !back! fo c u s!distance!could!be!sh o rte n e d,!this!the n!opens! up !space!to!move!th e!final!lens!
element!closer!to!the!image!sensor!—!and!if$t his $elem e n t$is$mad e$larg e!the n!an!equivalen t!control!for!
aberrations! of!the!ray!bundle!p roje cted !o n!to! th e!corner!of!the!imag e!sensor!can!be!made! —!as!shown!
in!the!lower!image!in!F igu re !10.!
! ! ! ! !
Figure&10! Showing$two$alternatives$in$lens$design$to$indep e n de n tly $and$gently$control$ aberrations$
of$the$ray$bundle$projected$on$to$the$corner$of$the$image$sensor&
11!
10.0&&&&&&&&&NEW&CONCEPTS&UNDERLYING&RF&LENSES&!
10.1&&&&&&&&&New&Feature&Unique&to&RF&Lenses&
The! new! RF! lens es ! represe n t! a! quite! radical! step! f or w a rd ! in! le n s! design s ! that! anticipa te ! the! future!
imaging !n e ed s !of!an!increasingly!sophisticated!end!user.!
&
10.1.1&&&&&&Control&Ring&
A!significant!new!innovation! is!incorporated! into!the!design!of!these!lenses!—!a! special!knurled!control!
ring,!which!in!the!initial!RF!lens!embodimen ts !is!positioned!at!the!very!front!of!the!lens!—!before!the!
focusing!co n trol!rin g,!as!sho wn!in!Figure!11.!!It!capitalizes!on !the!augm e n te d !electronic!co mmunicatio n !
between! lens!and! camera!that!is!central! to!the!new! lens!design.! !!The! pu rpose!of! the!ring! is!to! facilitate!
intuitive! an d! flex ible ! acc es s ! to! adju st m e n t! of! Ap e rtu re ! valu e ! /! Shut te r! spe ed ! /! ISO ! and! Exposure!
Compensation.! !The!particular!function!selection! is!performed!in-camera!in!the!Custom!Function!menu.!!
In!the!new!lens e s!de sc rib e d !in!this!paper,!as!the!ring!is!rotated!it!clicks!(different!number!of!clicks!per!
revolution! for! different! RF! lense s )! which! serv es! to! provide ! a! sensory! cue! while ! the! photog rap he r! is!
looking!through!the! viewfinder.! ! The ! direction! of! rotation! can! b e! set! to! suit! user! preference.!!!And,!users!
have!a!choice! of!whether!control!ring !rotation!a ctu a lly !changes!e xp o s ur e!only!wh en !the!shutt er !button!
is!pres se d !half-way! (to!minimize!risk! of!inadvertent!changes),!or! to!h av e!any!moveme nt!directly!impact!
exposure!(with!no!need!to!first!hold!the!shutter!button!half-way!down).!!
! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !
Figure&11!! Showing$the$new$Control$Ring$that$extends$operational$flexibilities$for$the$photographer!
A! new! microprocessor! within!the! lens!has! improved! processing!capability! together!with!lower!power!
consumption! and! high-speed! com mu nication.!!The! increased! capacity! of! the! built-in! memo ry ! allows!
more!data!to!be!stored,!enabling!highly!accurate!lens!control! and!image!correction.!!This!is!especially!
importa n t!f or !th e !D igit a l!Le n s!Optimizer!feature!o f!the! RF!system .!
10.1.2&&&&&Aperture&Blade&Control&
!
The! new ! family! of! RF! lenses ! inco rp o ra te s ! an! important! new! feature! that! automatically! closes! the!
aperture!blades!one!or!two!steps!wider! than! the!sm allest!position!upon! power! close! down.! ! ! !This!helps!
protect!the!camera!image!sensor!and!shutter!blades!from!damaging!high!intensity!light!sources.!
12!
10.1.3! !!!!!!!!Focus&Ring&Rotation&Direction&Change!
!
The!RF!lens e s!all!incorpora te !an!ability!to !choose!th e !direction!of!rotation!of!the!man ua l!focus!cont ro l.!!!
In! p la ce !of! a!direct!mechanical!co n n ec tio n !from!focus!control!ring!to!th e!actual!focusin g!optics,!throug h !
a! threaded,! all! mechanical! helicoid,!the! system! uses! a! focus!ring! co nn ec ted ! to! a! se ries! of! m any ! very!
fine,! electronic ! c on tacts .! ! There's! no! d irec t,! m e ch an ical! connection! a t! a ll! to ! th e! group(s)! of! elements!
that!move!the!focusing!element.!!Ro tating !the!focus!ring!se nd s!a!series!of!very!specific,!fine!signals!to!
these!contacts.!!These!are!converted! into! signals!to!the!sam e!focus!motor!(USM,!Nano!USM,!etc.)! that's!
used!for!autofocus.!!The!motor!now!drives!the!lens!to!change!focus.!
Inheren t !to !t h is!s ys te m!there!is!a!cus to m!function!t o !ch a n g e!Manual!Fo cu s !d ire ct io n,!whic h !ca n !b e !an !
invaluab le !as se t !to !u se rs !tra n sit ion in g !to !C a n on !fr o m !c o m p e tit ive !sy s te m s . !!!Th is!also!benefit!users!who!
utilize!a!follow!focus!system!(external!gears!and!a!knob!to!control!focus)!.!
!
! !
!
10.1.4&&&&&&&Enhanced&Electronic&Communication&between&Lens&and&Camera&
!
The! new! RF! mount! uses! 12! contacts! instead! of! the! 8! contacts! of! the! EF! lenses! fo r! lens-cam era!
communication.! ! New ! communication! protocols! and! dedicated! communication! channels! are!
incorpo ra te d!—!which!support!large!data!transfers! a t!very!high!speeds!compared!to!current! EF!system.!!
The!new! RF!system!design!anticipates!ongoing!innovations!in!future!cameras!as!well!as!lenses.!!Even!
with!these!changes,!full!support!and!compatibility!for!existing!Canon!EF!and!EF-S!lenses!remain.!
!
!
11.0&&& INTRODUCTORY&FAMILY&OF&CANON&RF&LENSES&&
!
This!white!paper!will!outline!four!lenses!that!constitute!the!introductory!phase!of!the!new!RF!system:!
!
10.1! ! RF28-70mm!F2!L!USM!
!
10.2! ! RF50mm!F1.2!L!USM!
!
10.3! ! RF24-105mm!F4!L!IS!USM!
!!!!!!!!!
10.4!!!!!!!! RF35mm!F1.8!MACRO!IS!STM!!
!
13!
11.1& &&&&&&&&RF28-70mm&F2&L&USM&
RF28-70!F2! L!USM!is!a!large-diameter,! standard!L! zoom!lens! with!a! bright! F2.0!constant!aperture!across!
the!entire!zoom!range!—!the!new !28-70m m!F2.!!!The!lens!is!intended!for!professional!photographers,!
high-end!amateurs,!and!low- lig h t!moviemakin g .!!It!embod ies !high-speed!auto!focus! fun ctionality,!and!a!
Control!Ring!for!functional!assignment!of!exposure!controls.!
!!!!!!!!!!!!!!!!!!! !
Figure&12!!! The$new$RF28-70$F2$L$USM$—$a$compact$28-70mm$F2.0$zoom$lens$has$high$overall$
optical$performance$and$excellent$operational$empowerments$
The!lens! is! comprised! of! nineteen! elements! in! thirteen! groups.! ! The!large!diameter!moun t! and!the!short!
back!focus!are!used!to!particular!advantage!to!gain!the!higher! brig h tn e ss ! of! F2.0.!! !Th ese!two!factors!
mean! the! front! section! of! the! lens! can! by! physically! much! smaller! th an! conventional! EF! lens!
architecture.!!The!strategic!disposition!of!four!aspheric! lens!elements!(shown!in!light! green)! in!Figure!13!
helps!to!minimize!astigmatism,!spherical!aberration!and!geometric!distortion,!while!the!two!UD! and!o ne!
Super!UD!elements!(dark!green)!help!curtail!the!longitudinal!and!lateral!chromatic!aberrations.!
!
!!!!!!!!!!!!!!!! !!!
Figure&13&&&&&&There$ are!thirteen $groups$made$up$of$a$total$ of$nineteen$lens$elem en ts$in$the$RF28-70mm$
F2$L$USM$lens$
14!
The! new! RF! mount! made! possible! a! zoom! lens! having! an! ultra-large! dime te r! an d ! a! co n st a nt ! F2.0!
aperture! across! the! entire! zoom! range.! ! The! F2.0! maximum ! aperture! creates! an! excellent! creative!
bokeh.!!
!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !
Figure!14! ! Showing$the$operational$controls$on$the$RF28-70mm$F2$L$USM$lens$
This! remarkable! zoom! lens! is! represents! a! significant! step! forward! in ! terms! o f! t h e! F2.0! constant!
aperture,! generous!zoom!range,!and!a!size! and!weight!that!would!not!have! been!possible!in!an!EF!lens.!!
It!is!ideal!fo r!h a n d h e ld !s h o o tin g .!
15!
11.1.1&&&&&&&&&&&&&&&&&&MTF&Characteristics&of&the&RF28-70mm&F2&L&USM& Le ns&
The!MTF!curves!in!Figure!15!sh ow !the!behavior!of!this!lens! m easured!at! four!distances! from!the!image!
center.!!Two!spatial!frequencies!are!used!—!one,!at!the!low!10!line!pairs! per!millimeter!(LP/mm)!which!
is! an! importa n t! measu r e! of! the ! contrast ! of! the ! lens,! an d ! the! sec o n d ! is! at! a ! higher! 30! LP /mm! which!
indicates ! re so lv ing ! p o w e r.! !T wo!separate !measureme n ts ! are ! made!for!ea ch ! a t! rig ht ! an g les ! to ! ea c h! o th e r. !!
The!term! “image!height”!refers! to!how!far!toward!any!of!the! four!corners!of!the! image!a!measurement!
is!taken!a s!s h o w n !in !th e !fig ur e!b e lo w .!
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& &&&&
&
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& &
&&&&&&&&&&&&&&&&
&
Figure& 15$$$$$MTF$characteristics$of$the$RF28-70mm$F2$L$USM $—$the$ w ide$ a pe rture $s etting $o n $th e$ left$ an d $
telephoto$on$right$
16!
11.1.2&&&&MTF&of&RF28-70mm&F2&L&USM&and& Equivalent&EF&Zooms!
Figure!16!shows!the!MTF!curves!for!the!new!EF28-70mm !F2!L!USM!on!the!right!compared!with!those!of!
two!establishe d!EF !zoo m !lense s!—!with!all!three!lenses!set!at!m aximum!aperture.!!Of!special!note!are!
the!following:!
1. 10!Lp/mm!Sagittal!of!the!new!F2!lens!is!very!close!to!that!of!the!EF24-70mm!f/2.8L!II!USM!lens!
(slightly!better!at!m aximum!image!heig ht)!an d !is!much!higher!than!the!EF24-70mm!f/4 L!IS!USM!
lens!at!m a x !he ig h t!!!
!
2. 10!Lp/mm!Meridional!approximates!the!performance!of!EF24-70mm!f/2.8L!II!USM!at!the!image!
extremity,!!but!it!!is!much!better!than!the!EF24-70mm!f/4L!IS!USM!lens !at !maximum!image!
height!
!
3. 30!Lp/mm!Sagittal!behavior!is!considerably!better!!than!the!EF24-70mm !f/2.8L!II!USM!at!
maximum!image!height!and!is!far!higher!than!that!of!the!EF24-70mm!f/4L!IS!USM!
!
4. 30!Lp/mm!Meridional!curve!for!the!RF28-70m m!F2!L!USM!is !h igh e r!fro m!image!cen te r!to !a n !
image!h e ig ht !o f!1 5 m m!than!both !E F!z o o m !lenses!and!is!equivalent!to!EF24-70mm!f/2.8L!II!USM!
at!image!extremity!—!but!much!better!than!EF24-70mm!f/4 L!IS!USM!at!the!extremity!
!
Figure&16! Comparative$MTF$Behavior$of$RF28-70mm$F2$L$USM$versus$equivalent$EF$zoom$lenses$at$
the$wide$ang le$setting $(a ll$lense s$set$to $m ax im um$aperture)$
17!
Figure!17!shows!the!MTF!curves!for!the!telep hoto!end!of!all!three!zo om !lenses.!
1. 10!Lp/mm!Sagittal!is!slightly!higher!than!both!EF!lenses!at!the!far!corners!of!the!image!
!
2. 10!Lp/mm!Meridional!is!essentially!equivalent!to!that!of!the!EF24-70mm!f/2.8L!II!USM!but!is!
higher!than!that!of!EF24-70mm!f/4L!IS!USM!
!
3. 30!Lp/mm!Sagittal!is!higher!than!bo th !E F !len s e s!a t!th e !2 2 !mm!height!
!
4. 30!Lp/mm!Meridional!is!essentially!equivalent!to!that!of!the!EF24-70mm!f/2.8L!II!USM!out!
to!15mm !heigh t!—!but!is!higher!at!the!22mm!extremity!
!
5. !30!Lp/mm!Meridional!is!higher!than!that!of!the!EF24-70mm!f/4L!IS!U SM!out!to!15mm!away!
from!imag e!ce nte r! —!and!is!significantly!!higher!at!the!22mm!extremity!
!
Figure&17!!!!!$$Comparative$MTF$Behavior$of$RF28-70mm$F2$L$USM$versus$equivalent$EF$zoom$lenses$at$
the$telephoto$en d$o f$their$resp ective $zoo m $ran ges$$$
18!
11.2& &&&&&&&RF50mm&F1.2&L&USM&
This! is! a! large! diameter! standard! single-focus! lens! employing! the! new! standard! RF! mount.! ! At! its !
maximum! aperture!of!F1.2!the!lens!m aintains!high!sharpness!at!image!center!with!well!controlled!falloff!
of!MTF!toward!the!image!extremities.! !!Th e!lens!is!designed!to! extend!the! creative!photo!expressiveness!
for!profession al!ph ot ographers!and!high-end!amateurs.!
!!! !
Figure&18! The$new$RF50mm$F1.2$L$USM$features$high$overall$o p tical$perform a nce$and$innovative$
operational$functionalities$$$!
The!lens!is!a!totally!new!optical!design,!comprised!of!fifteen!elem ents!in! nine! groups.! ! The! rear!elem ents!
capitalize!on!th e! sh o rt! flang e! b ack ! of! th e! EO S!R!system!—!their!large! size ! con tribu ting!to!the!high ! op tical!
performance.!!The!first!eleven!elements!constitute!the!focusing!optics.!!The!lens!h as!a!m inimu m !focal!
distance!of!40!cm!(15.7!inches)!and!maximum!magnification!is!0.19x.!
!!!!!!!!!!!!!!!!!!!! !
Figure&19! Showing$the$ nine$groups$made$up$ of$a$total$of$fifteen$lens$elements$within$the$RF50mm$
F1.2$L$USM$lens$
19!
The! lens! deploys! three! high-refraction! aspheric! elements! —! show n! in! green! in! Figu re! 19.! ! Chromatic!
aberrations!are!minimized!using!the!UD!element!(dark!gre en ).!!!
Flare!and!ghosting!are!particularly!w ell!controlled!using!Canon’s!Super!Spectra!Coatings!—!with!the!Air!
Sphere! Coating! (ASC)! technology! on! one! critically! positioned! le n s! e lement! shown ! in ! Fig u re ! 19.! ! ! A ir!
Sphere!Coating!is!an!anti-reflection!technolo gy!that!co m b ine s!the!existing !vapor-deposited!multi-layer!
coatings!w ith!an!u ltra-lo w!refra ctive!index!outermo st!layer.!!AS C!significantly!reduces!flare!and! gh ostin g!
that! cannot! be ! prev en ted ! with! co nv en tiona l! vapo r-deposited! multi-layer! coatin g s,! improving! anti -
reflection!performance.!!
This!lens!is!a!striking!example!of!the!powerful! new !flexibility!offered!by!the!new!RF!mount!in! achieving!
the!F1.2!brightness!in!a!com pact!lens.!!!To!achieve!this!level!of! optical!quality!in!an! F1.2!design! with!the!
standard! EF! mou nt! wo uld! ha ve! entailed ! a ! s ign ific a n tly! larger! len s.! ! The!lens! enables!close-ups! from! a!
closest!focusing!distance!of!1.31!feet!and!produces!beautiful!bokeh!from!a!circular!aperture!with!a!10-
blade!iris.!
The!focusing!actuator!is!a!ring!U SM!(ultrasonic!m otor).!!!The!lens!has!a!10-blade!aperture!actuated!by!
EMD!(Electro!M agn e tic!Dia ph rag m)!which!supports!beautiful!rendering!of!out-of-focu s!ba ckg rou n ds .!
The!front!filter!size!is!77!mm.!
!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!$$ $
Figure&20! Showing$ the$ Focus$ Mode$ and$ Focus$ Distance$ Range$ Selector$ switches$ while$ also$
outlining$where$dust$and$water$sealing$design$precautions$have$been$implemented$
20!
11.2.1&&&MTF&Characteristics&of&the&RF50mm&F1.2&L&USM&lens&compared&
to&EF&Lenses&
Figure!21!shows!the!MTF!characteristics!of!the!RF50mm!F1.2!L!USM!lens!at !th e!maximum !rela tiv e !
aperture!setting!of!F1.2.&&!
&&&&&&&&&&&&&&&&&&&&&&&&& &&&&&&&&&&&&&&&&&&&!
&Figure&21$$$$$$$$$$The$10$and$30$Lp/mm$MTF$curves$for$RF50mm$F1.2$L$USM&
!
!
Figure&22!!!!Comparing$the$M TF$characteristics$of$the$RF50mm$F1.2$L$USM$lens$with$t w o $5 0 m m$EF$lenses$
21!
1. 10!Lp/mm!Sagittal!of!the!RF50mm!F1.2!L!USM!lens!maintains!a!significantly!higher!MTF!across!
the!total!image!h eigh t!com p are d!to!b oth !EF!len ses !(and !esp ecially!co m pa red !to!the !EF5 0m m !
f/1.2L!USM)!
!
2. 10!Lp/mm!Meridional!exhibits!an!excellent!MTF!characteristic!compared!to!both!EF!lenses!!
!
3. 30!Lp/mm!Sagittal!exhibits!a!higher!and!more!controlled!MTF!across!the!total!image!height!than!
the!two!EF!lens es!!!
!
4. !30!Lp/mm!Meridional!curve!for!RF50mm!F1.2!L!USM!lens!also!shows!an!excellent!characteristic!
that!is!superior!to!that!o f!bo th!EF !lense s!
!
11.3&&&&&&&&&&&&RF24-105mm&F4&L&IS&USM&
RF24-105mm! F4! L! IS! USM ! is! a! medium-diameter! standard! zoom ! lens! with! an! F4.0! con stant! aperture!
over! the! entire! 24-105mm! focal! ran ge .!!It s! minimum! a p er tu re ! is! F 2 2 .! ! ! Th e! le n s ! is! int e n d ed ! fo r !
professional! photographers,! high-end! amateurs,! and! low-budget! moviemaking .! ! It! embodies! an!
enhanced! image! stabilization! system,! high-speed! auto! focus! function ality,! and! the! innovative! new !
knurled!control!ring!for!fun c tio n al!a s sig n ment!of!expos u re !co n tro ls .!
! ! !!!!!!!!!
!
Figure&23! The$ new $RF24-105$F4$L$IS$ U SM$has$high$operational$ functionality$and$impressive$optical$
performance$in$an$unusually$compact$size$$
Even!with!the!built-in!image!stabilizatio n !system!the!size!and!w eight!have! be en!minimized!to!allow!easy!
hand-held! shooting.!!Minimum! focusing! distance! is! 0.45m! (1.48! feet).!!!!The! lens! is! comprised! of!
eighteen! elements! in! fourteen! groups.! ! This! is! a! particularly! interesting! example! of! unusually! large!
diameter!rear!elements!capitalizing!on!the!short! flange!back!of!the!RF!system!—!with!this!combination!
contributing!to!the!high!optical!performance!of!the!image!projected!onto!a!large!Full!Frame!sensor.!!! !!
22!
!!!!!!!!!!!!!!! !
Figure&24!!!!!!!!Showing$the$fourteen$groups$made$up$of$a$total$of$eighteen$lens$elements$in$the$RF24-
105mm$F4$L$IS$USM$lens$
Strategic!disposition!of!three!aspheric!lens!elements! (shown!in!light!green!in! Figure!24!helps!correct!for!
astigmatism,!spherical!aberration,! and!geometric! d istortion.!!The!U D!lens! element!shown!in!dark!green!
helps!minimize!both!lateral!and!longitudinal!chromatic!aberrations.! !The! Com pensation!Optics!group!in!
the!center!is!the!lens!element!group!which!performs!the!image !stab ilization!correction.!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !
Figure&25! Showing$the$Zoom,$Focusing,$and$Control$rings$and$the$various$mode$switches$
23!
Because! the! focu sing ! element! (“focus! lens”! in! Figure ! 24! above)! is ! small! and! lightweight!the! focusing!
actuator! deploys! a! Nano! USM! (ne w ! Thin -type).! ! This! motor! uses! the! basic! Ultrasonic! principle,! of!
extremely!controlled,!fine! vibrations! produced!by!running! current!through!a! specific!metal!device.!!In!
this!case,!the!"device"!looks!almost !like!a!t in y!meta l!banda g e,!with !little!project in g !nubs!on!either!side!
—! Figure! 26.! ! These! in ! turn! co ntact! a! sliding! surface,! and! vibrations! are! transformed! into! linear!
movement,! and! a! lens! element! guided! by! a! control! bar! moves! fore! or! aft! to! drive! fo cu s! in! either!
direction.!!&&&
&&&&&& !
Figure &2 6! !!!!Showing$the$Nano$ USM $ used$ to$ actuate$ the$focusing$ element$ in$ the$ new$ RF24-105mm $
F4$L$IS$USM$zoom$lens$
The!Nano!USM!is!very!quick!an d!quiet!and!is!particularly!well-suited!to!stop-and-start!operation!that's!
quite!common!in!video!shooting.!!It!also!helps!ensure!much!smoother!AF!during!video!acquisition.&
&
11.3.1&&&&&&&&&&&&&&&&&&MTF&Characteristics&of&the&RF24-105mm&F4&L&IS&USM&Zoom&Lens&
&&&&&
Figure&27$$$$$$$MTF$characteristics$of$the$RF24-105mm$F4$L$IS$U SM$$le n s$a t$b o th $t he $wide$end$and $th e $
telephoto$end &
24!
Figure!28!shows!the!MTF!curves!for!the!new!RF24-105mm!F4!L!IS!USM!on!the!left!compared!with!those!
of!two!established!EF!zoom!lenses!—!for!the!wide!e nd !of!the ir!resp ectiv e!zo om!ranges.!!Of!special!note !
are!the!following:!
1. 10!Lp/mm!Sagittal!is!slightly!lower!than !that!o f!the!EF 24 -105mm!f/4L!IS!II!USM!lens!e xc e p t!a t!th e !
extreme!!corners!of!the!image!!
!
2. 10!Lp/mm!Meridional!maintains!a!higher!MTF!from!image!center!to!a!height!of!15mm!than!both!
EF!lenses!—!and!it!approximates!the!performance!of!EF24-105mm!f/4L!IS!II!USM!at!the!image!
extremity!
!
3. 30!Lp/mm!Sagittal!behavior!is!slightly!better!!out!to!an!image!height!of!15mm!than!the!EF24-
105mm!f/4L!IS!II!USM! but!is!hig h er !th a n!t h at !o f!th e !E F2 4 - 105mm!f/3.5-5.6!IS!STM!
!
4. At!image!extremity!the!RF24-105mm!F4!L!IS!USM!maintains!a!higher!Sagittal!MTF!than!both!EF!
zooms!
!
5. 30!Lp/mm!Meridional!curve!for!the!RF24-105mm!F4!L!IS!USM!is!higher!f ro m !image!center !to !an !
image!h e ig ht !o f!1 5 m m!than!both !E F!z o o m !lenses!and!is!equivalent!to!EF24-105mm!f/4L!IS!II!
USM!at!image!extremity!—!but!much!better!than!EF24-105mm!f/3.5-5.6!IS!STM!
&
Figure&28! Comparative$MTF$behavior$of$RF24-105mm$F4$L$IS$USM$versus$equivalent$EF$zoom$
lenses$a t$th e $w id e $a n g le$s et tin g$
25!
Figure!29!shows!the!MTF!curves!for!the!new!RF24-105mm!F4!L!IS!USM!on!the!left!compared!w ith!those!
of!two!established!EF!zoom!lenses!—!for!the!wide!e nd !of!the ir!resp ectiv e!zo om!ranges.!!Of!special!note!
are!the!following:!
1. 10!Lp/mm!Sagittal!for!RF24-105!F4!L!IS!USM!is!slightly!lower!across!the!image!height!than!that!of!
the!EF24-105mm!f/4L!IS!II!USM!except!at!maximum!image!height!
!
2. 10!Lp/mm!Meridional!exhibits!a!lower!MTF!from!image!center!to!a!height!of!15mm !th an !bo th!EF !
lenses!—!and!it!approximates!the!performance!of!EF24-105mm!f/3.5-5.6!IS!STM!at!the!image!
extremity!
!
3. 30!Lp/mm!Sagittal!behavior!is!slightly!higher!at!an!image!height!of!15mm!than!both!EF!lenses!!
!
4. 30!Lp/mm!Sagittal!!!is!slightly!higher!than!both!EF!lenses!out!to!15mm!height!!
!
5. 30!Lp/mm!Meridional!curve!for!RF24-105mm!F4!L!IS!USM!is!very!similar!to!both!EF!lenses!out!to!
15mm!image!height!!!!an d!at!image!extremity!is!higher!than!EF24-105mm!f/3.5-5.6!IS!STM!and!
slightly!lower!than!EF24-105mm!f/4L!IS!II!USM!!
&
Figure&29! Comparative$MTF$behavior$of$RF24-105mm$F4$L$IS$USM$versus$equivalent$EF$zoom$
lenses$a t$th e $w id e $a n g le$s et tin g$
26!
11.4&&&&&&&&RF35mm&F1.8&MACRO&IS&STM&&
RF35mm!F1.8!MACRO!IS!STM!is ! a ! w id e ! a n g le! macro!lens ! employing!the!new!standard!RF!mount!having!a!
maximum! aperture! of! F1.8! and! a! 0.5x! magnification.! ! It! h a s! a! minimum! aper tu re ! of! F22.! ! ! This! is! a!
moderate! wide-angle! lens! with! a! compact! overall! design,! ideally! suited! to! traditional! candid! street!
photography!and!low-light! ima g ing .! !!!It! c o mbines! beau tif u lly! with!the!smaller!mirrorless! cam era! as! a!
lightweig h t,! tra ve l! an d! lo ca tio n ! orie n te d ! lens! for! serious! enthusiasts.! ! ! In! spite! of! its! F1.8! maximum!
aperture,! it! doubles! as! a! true! macro! lens,! with! ability! to! fill! the! frame! with! a! subject! as! sm all! as! a!
business! card! at! its! nearest! focus! dista nc e.! ! Finally,! it! o f fe rs ! optical! Image! Stabilization,! further!
enhancing!its!abilities!in!low-light!sit u at io ns .!
!!!!!! !
Figure&30& The$new$wide$angle$RF$lens$ —$RF35mm$F1.8$MACRO$IS$STM$
The!lens!is!comprised!of!eleven!elements!in!nine!groups!—!Figure!31.!!The!rear!elem e nt s!capita lize !on!
the!short!flange!back!of!the!RF!system!—!having!a!particularly!large!diameter!contributing!to!the!high!
optical! pe rfo rmance.! ! The! first! nine ! elements! constitute! the! focusing! optics,! and! the s e ! are ! moved! in!
tandem! as!fo cu sing !is!ca rried! ou t.!!An!aspheric!element!in!the!focusing!group!reduces!aberrations!during!
focusing.! ! The! lens! is! a! co mp act,! lightweight,! and! large-diameter! wide-angle! lens! wit h! the! ability ! t o !
provide! 0.5x! macro! shooting,! by! using! front-lens! foc u s! toget h er! with ! forwa rd ! placement! of! the!
diaphragm!and!a!lighter!focus!group.!!!The!lens!has!a!minimum!focusing!distance!of!0.17m!(6.7!inches).!
!
!!!!!!!!!!!!!!!!!!! !
Figure&31! Optical$system$of$the$new$RF35mm$F1.8$MACRO$IS$STM$lens !!
27!
The! lens! has! the! new! control! ring! —! with! 54! clicks! per! revolution.!! ! It! has! a! high! performing! optical!
image!stabilization!system!with! shake-correction!allowing!hand-holding!at!shutter! speeds!up!to!5-Stops!
slower!than!would!norm ally!be!possible!—!impressive !fo r!a!lens!having!a!brightness!of!F1.8.!!!
In! two! key! areas! a! not ab le ! improvement! was!implemented! in! this!new! 35! mm ! lens! co m p a re d ! to! th e !
well-known! EF35 mm ! f/2! IS!USM !le n s.!!The! o ve ra ll!length!o f! t h e!lens’s! o p ti ca l!path!is !shortened!from!1 0 5 !
mm! to!80.5!mm! and!the!all—impo rta n t! opera tio n a l! optical! speed ! of! the! lens! is! now! F1.8.!! Figure! 32!
shows!EF!35mm!f/2!IS!USM!on !th e !le ft!c o mpared!to!th e !n e w !le n s!on!the!right.!!!!
!!!!!!!!! !
Figure&32& !!!New! RF35mm $ F1.8$ M ACRO $ IS$ STM$ lens$ (on$ the$ right)$ having$ a$ large$ diameter$ rear$
element$helps$optimize$the$overall$image$performance$proje ct ed $o n $to $t he $full$fram e $im ag e$se ns or$
!
A!comparative!inspection!of!these!two!lenses!quickly!reveals!a!quite!radical!ch an ge!to!the!o vera ll! op tical!
assembly.!!!Note!the!large!final!lens!element!of!the!RF35mm!F1.8!MACRO!IS!STM!compared!to!that!of!
the! EF!lens.!!Of!sp ec ial!interest!are!the! sm aller!front! elements! in! the! new! lens!—!which!still!achieves!the!
faster!F1.8!maximum!aperture!because!of!the!large!diameter!iris!that!is!positioned!unusually!near!the!
front!of!the!lens .!!!The!entire!front!section!is!moved!to!focus!this!la test!35!mm!lens.!!!!But,!it!is!much!
smaller-diameter! and! lighter! in! weight,! making! it! p oss ible! to! s w itch! from! a! rin g-ty pe ! USM! to! the!
stepping!motor! (ST M )!focus! d rive!system.!!A mo ng!other!benefits,! this!change!to! STM !focus!drive! m eans!
much!smoother!focus!performance!when !the!len s -camera!system!is!used!for!v id eo !s h oo t in g. !
!!!
!
!
28!
!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Figure&33!!!!!MTF$curves$for$RF35mm$F1.8$MACRO$IS$STM$lens!
!
Figure&34!!!!!!!MTF$characteristics$of$the$new$RF35mm$F1.8$MACRO$IS$STM$lens$c ompared$to$two$35mm $
EF$lenses$
The! new! RF35mm! F1.8! MACRO! IS! STM! has! remarkably! similar! MTF! characteristics! to! those! of! the!
excellent!EF35mm!f/1.4L!lens.!!But!it!is!a!more!co mpact!an d !lightweight!lens!an d !has!a!macro!shooting!
capability!at!f/1.8 !brightness!that!cannot!be!matched!b y!any!EF!len s.!!The!control!algorithm!of!the!new!
optical!IS!augments!the!Dual!Sensing! IS!of!the!EOS!R!lens-camera!system,!providing!high!image!stability!
in!macro !p h o to g ra p h y!u sin g !u p !to !5 !st o p s!s hu t te r!sp e e d .!!!!
$
29!
1. 10!Lp/mm!Sagittal!for!the!new!RF35mm!F1.8!MACRO!IS!STM!lens !maintains!a!slightly!higher!MTF!
across!the!total!image!height!compared!to!the!EF35m m !f/2!IS!USM!and!is!much!lower!than!that!
of!the!EF35mm!f/1.4L!II!USM!
!
2. 10!Lp/mm!Meridional!exhibits!a!lower!M T F !th an !b o th !E F !3 5 m m!lenses!!
!
3. 30!Lp/mm!Sagittal!for!the!RF35mm !F1.8 !M AC R O!IS!ST M !is!somewha t!s imilar!to!that!of!th e !
EF35mm!f/2!IS!USM!out!to!15mm!height!but!slightly!higher!at!maximum!image!height!but!is!not!
as!well!controlled!as!the!EF35mm!f/1.4L!II!USM!
!
4. 30!Lp/mm!Meridional!curve!for!RF35mm!F1.8!MACRO!IS!STM!lens!is!no t!a s !h igh !a s!t h at !o f!th e !
EF35m m!f/1.4L!II!USM!and!is!somewhat!similar!to!that!of!the!EF35mm!f/2!IS!USM!
!
!
!
!
!
12.0&&&&&&EF&LENS&MOUNT&ADAPTERS&&&&&!
The!intent!of!the!EOS!R!system!is!to!build!upo n!the!highly!successful!Canon!EOS!system!and!take!it!to!
new! levels! of! performance! and! operational! flexibilities! for! both! digital! still! and! motion! imaging.!!!!
Central!to!the!strategy!is!the!Mount!Core!Design!—!the!new!RF!mount.!!Folding!the! existing!world!of!EF!
lenses!(including!EF-S!lenses)!into!this!expanding!imaging!universe!is!a!pivotal!part!of!the!overall!plan.!!
To!do!this!three!special!adapters!have!been!developed :!
1. Mount&Adapter&EF-EOS&R&
Direct! me ch a n ica l! and ! electric al! cou p lin g! between!the ! EF! lens! and ! any! the!new!EOS!R!
camera!and!any!future!EOS!R!cameras!!
!
2. Control&Ring&Mount&Adapter&EF-EOS&R&
An!adapter! for!e xistin g!a nd !future!EF!lenses!that!incorporates!th e!same!innovative!n ew !
ring! fo r!control!of!exposure! that!is!found! on!RF!lenses.!!When!the! rin g !is!rotated!a!built-
in! s en s o r! and! microp ro c es so r! detec t! and! proces s! that! motio n ! which ! is! transmitte d ! to!
the!camera !via!th e!co nta cts!
!
3. Drop-In&Filter &Mount&Ada p te r&E F-EOS&R&&&
A! m ount!adapter! for!EF! lenses,!with! dedicated! drop-in !filter!slo t.!!It!allow s!ad dition !of!a !
Canon!Drop-In!Circular!Polarizing!Filter!A!(w ith!full!rota tion !capabilities!in!the!adapter),!
or! a!Canon!Drop-In!Variable! ND!Filter!A!with!range!of!1.5–9!stops.!!An!available!Drop-In !
Clear!Filter!A!should!be!used!whenever!the!two!specialized!filters!are!not!in-place.!
30!
12.1&&&&Mount&Adapter&EF-EOS&R!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
Figure &35! Mount$Adapter$EF-EOS$R$that$a da pts $EF$lens es$to$the $new $RF$mount$
!
12.2&&&&&&Control&Ring&Mount&Adapter&EF-EOS&R&
!!!!!! !
Figure&36! Control$Ring$Mount$Adapter$EF-EOS$R$that$incorporates$the $con trol$ring$
31!
12.3& Drop-In&Filter&Mount&Adapter&EF-EOS&R&
&&&&&&&&
&
Figure&37&Drop-In$Filter$Mount$Ada pt e r$E F-EOS$R$showing$the$various$options$for$the$drop-in$optic a l$
filters&
!
!
&
&
13.0!!!!!!!&&&&EOS&R&LENS-CAMERA&SYSTEM!
The!EO S!R!system!incorpo rates!a!v ariety!of!op erational!empowerm ents!that!have!been !made!possible!
because! of! new! innovation! in! the! new! lens! series! and! the! high-speed! electronic! commu nication!
between!the!lens!and!the!camera.!
!
13.1&&&Enhanced&Image&Stabilization&System&
High!picture!sharpness!is!ensured!as!long!as!each!point!of!the!image!rem a in s!precisely!positioned!on!the!
imager! se n so r.! Le ns -camera! shake! is! a! significant! cause! of! blurred! im ages.! Minute! deflections! and!
tremors!to!the!lens-camera!momentarily!shifts!the!pro jected !image!around!th e!imager!sensor!plan e!—!
causing!inadvertent!image!unsteadiness!in!the!displayed!image,!with!an!associated !blurr in g !and!loss!of!
picture! sharpness.! These! lens-camera! disturbances! include! jolting! associated! w ith! hand held! and !
shoulder! mounting! by! a! camera! operator! who! is! in! m otion,! vibrations! when! tripod! m ounted! on! an!
unstable! platform! or! in! windblown! environments,! to! the! higher! vibration! frequencies! encountered!
when!operating!on!vehicles,!boats,!and!aircraft.!!
32!
In!the!new!EOS!R!system!the!lens!emb od ies!new !technologies!that!combine!with!the!IS!system!in!the!
camera! to !impleme nt!an!augmented !control!over!the!im ag e!blurring!that! ca n!be!caused!by! sh akin g!and!
vibration! of! the! lens-camera! system.!!This! is! empow ered! by! an! interactive! data! communication!
between! the! two.! ! ! Within! the! lens! a! dual! gyro! sensor! system! detects! any! inadvertent! physical!
movements!of!the!system!and!this!data!is!reported !acro s s !len s-camera!communication!to!the!DIGIC!8!
processor.! ! ! At! the! same! time! the! image! sensor! is! “seeing”! any! blur! stimulated! by! these! same!
movements!and!it!also!reports!this!image !data! to!the !DIGIC!8!processor.!!These! two!data!reports!are!
algorithmically!processed!at!very!high!speed!and!a!compensation!control!signal!is!gen erated!and!sent!
back!at!high!speed!to!the!lens!to!actuate!the!IS!optical!element!that!counteracts!the!disturbance.!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
Figure&38& $ $$$$$$$The$ lens$ gyro$ sensor$ reports$ lens$ m ovem ents$ and$ the$ image$ sensor$ reports$
associated$blur$data$to$the$DIGIC$8$processor$
During!video!recording!there!is!the!added!ability!to!combine!any!optical!Image!Stabilization!in!the!lens!
with!electronic!Image!Stabilization!within!the!CMOS!image!sensor.!!!Combination!IS!adds!five!a xis!degree!
of!control! electronic!IS!at!the!image!sen sor!as! show n!in! Figure!38,!in!addition !to!the!up /d o wn,!left/right!
stabilization!typically!carried!out!in!the!lens.!!The!lens!IS!system!e x ercises!correction!in!the!Yaw,!Pitch,!
and! Roll!directions!—!see! Figure! 39.!! !!The!in-camera! stabilization!system ! exercises ! additional!control!
over!Yaw!and!Pitch!—!as!well!as!correction!in!Roll!and!the!vertical!and!horizontal!planes.$
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$ $
Figure&39$ Showing$the$five$dim e n sio n s $o f$image$stabilizat io n$c o rre ct io n$in $t h e$EOS$R$cam era$
33$
13.2& &&&&&&&Digital&Lens&Optimizer&(DLO)&Syste m&
The!Digital!Lens!Optimizing!system!is!b uilt!into!the!EOS! R! camera! and! is!intended! to!implem ent!real-
time!c orre ction s!for!a!n um b er!of!optical! aberrations!and!distortions!encountered! over!a!wide! range!of!
shooting!conditions.!!Before!the!light!rays!reach!the!CMOS!image!sensor!they!pass!through!the!multi-
element!lens!and!various!filters!as!illustra te d !in!Figure!40.!!!!
!
Figure&40! A$simplistic$rendition$of$the$path$of$the$light$ray$that$enter$the$lens$and$are$ultimately$
projected$on$to$the$camera$image$sensor$
A! point! light! source! that! travels! through! a! lens! system! encounters! num erous! aberrations! —! both!
monochromatic!and!chromatic!—!that!ten ds!to!spread! th at!light.!!!Th e!optical!scientists!speak!of!a!Point!
Spread!Function.!!!!However,! the!cumulative!effect!of!the!aberrations!is!to!create!a!range!of!shapes!in!
that!sprea d! fu nc tion !a nd ! th ey! a re! affe cte d! b y! the ! im age ! he ight! a nd ! by ! the !o p eration al! settin gs! o f! zoo m ,!
focus,!and!iris.!!!!!
There! are!two!basic!limitations! to!image!resolution! within!all! lenses!—!the! first!is!the!cu m ulative !effec t!
of! the! six! monochromatic! and! chromatic! aberrations! (termed! the! defocusing! distortions! and! which!
worsen!as!the!lens!aperture!approaches!maximum),!and!the!second! is!diffraction!(which!worsens!as!the!
lens!ape rtu re !is !st o pp e d !d o w n )!—!see!Figure!41.!!!
!
Figure&41! Cumulative$ optical$ aberrations$ place$ limits$ on$ lens$ resolution$ near$ wide$ aperture$
settings$and$diffraction$places$other$limits$as$the$lens$aperture$is$stopped$down$
34!
!!!!! !
Figure&42!!!!!Showing$the$ stored$ data$ files$ on$ lens$ aberrations$ and$the$real-time$ len s$operational$controls$
communication$across$to$the$DLO$engine$within$the$EOS$R$camera$
!
The$DLO$system$can$implement$corrections$for$the$following$$
!
1. Resolution!loss!due!to!cumulative!aberrations!
!
2. Resolution!loss!due!to!diffraction!
!
3. Lateral!chromatic!aberration!
The! Digital!Lens!Optimizer!is! particularly!useful!when!u sing! lenses!that!are! p rone!to!optical!distortion!or!
blur,!often!providing!substantial!improvements!in!image!quality.!
In!photographic!circles,!many!will!stop!do wn !slightly!from! ma ximu m! aperture! wh en!taking !ph otos!w ith!a!
shallow! depth! o f! field! for! a! blurry!effect,! or! for!scen es! requ iring! a!fast! shutter! speed.! This! is!done! to!
prevent! a!degradation!of!resolution!in!the!focal!area.!!When!Digital!Lens!Optimizer!is!used ,!high! image!
sharpness! with! m inim al! aberrations! can!be! achieved! even ! w ith! m aximu m ! ape rture.!!Whether! using!a!
fast! shutte r! speed! to! capture! a! special! momen t,! or! a ! sha llow! d epth! of! field! for! a! blurry! effect,! the!
desired!aperture! can! be! chosen!freely.!A! w ider! aperture! also! allows!lowering!the!ISO! speed! for! even!
better!image!quality.!
Using!a! great!depth! of!field!for!pan! focus!is! one! of! the! standard!techniques!of! photography.!But! this!
involves!a!tradeoff ,!becau se !sma ll!apertu re s !could!not!be!used!if!softening !of!the!image!cause d !by!the!
diffraction!effect!was!to!be!avoided.!!With!th e !Digital!L en s !Optimizer,!the!entire!range,!from!fully!o p e n !
to!m in im um !aperture,!can!be !used,!g iving!free! reign!to!c rea tivity.!!!!Even! at! middle! range!F-stops,!where!
image! quality! is! ge n er ally ! good,! aberratio ns ! and! diffraction! used! to! re du c e ! image! quality! to! a! certain!
extent.!Shutter!speed!can!be!at!will,!regardless!of!aperture!stop .
35
In! t h e!EOS!R!system,!Digital!Lens!Optimizer! can ! b e!applied!in -camera!when!the!RAW!files!are!converted!
to! JPEG ! image! files,! and! use rs! can! expe ct! improvem en ts! in! fine! detail! and! resolution,! es pe cially! with!
subjects !h av in g!lo t s!o f!inherent!detail!(think !grass!a nd !foliage !in!lan d sc a pe s ,!tex tu re s !in!fashion!fabrics,!
etc.).!!If!RAW !images!are!recorded!and!then!processed!in!Canon ’s!Digital!Photo!Professional!software,!
similar!benefits!can!be!applied!in!processing!the!images.!!!
!
!
13.3&&&&&&&&&&Dual&Pixel&CMOS&AF!
EOS! R! system ! embodies! a! powerful! auto! focus! system ! where! the! sen sing! o f! sharp ! focu s! takes! place!
within!the! image!sensor!photosite!itself.!! ! It!mob ilize s ! the! du a l! photod io des!within ! each! p h o t o sit e ! to!
create! two! separate! images! that! facilitates! a! phase! detection! system ! that! indicates! the! d egree! of!
defocusing.!!
!!!!!!! !!
Figure&43! Showing$the$dual$photodiode$structure$of$a$single$photosite$in$the$CMOS$image$sensor$
used$in$the$EO S$R$camera$
$
$
$
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Figure&44! Showing$ the$ separate$ processing$ of$ the$ dual$ pixel$ data$ from$ the$ imag e$ sensor$ —$ for$
video$and$for$Auto$Focus$—$at$the$entry$sta ge $of$the$D igic$8$ processor$
Figure!44!illu s tra te s !the!m a n n er!in!wh ic h !the!se ts !of!dua l!pixel!o ut p u ts!from! t he !CMOS!image !sensor!are!
sent!to!the!DIGIC!8!processing!microcircuit!that!was!developed!by!Canon.!!W ithin!this!processor,!these!
streams! are! separately! fed! to! the ! primary ! RGB! video! proce ssing ! system! (where! the! two! photodiode !
signals!are!summ ed)!an d! to!a! data!processing! system! that!analyzes!the!phase!difference!between!the!
two!and!makes!all!of!the!decision-making!and!data!processing!associated!with!the!Auto!Focus!system.!!!
While! all!of! the! millions!o f! photosites!are! delivering!the! “dual! pixel”! data,! the! op eratio na l! aspects! of!
Auto!Focus!dictate!that!only!a!select!number!of!these!are!activated!at!any!given!time.!!This!is!because!
the!cam era !operator!(or!for!the!camera,!when!AF!me tho d s!like!Face!Detect!+!Tracking!are!active)!will!
make!the!decision!on!which!particular! subject! within!the!overall!picture!frame!is!chosen!for!sharpest!
focus.!!Consequently,!a!cursor!typ e !system!mu st!be!implem e n te d!to!facilitate!this!choice.!!!Experiences!
gained!in!the!early!generations!of!Dual!Pixel!CMOS!AF!system s !p ro d u ce d !th e !fo llo w in g : !
1.!!!Broad!request!to!provide!spatial!movement!of!the!sampling!area!—!so!that!different!subjects!
within!a!given!scene!can!be!selected!for!sharpest!focus!
!!!!!!!!!!!!!!!2.!!Ranging!performance!improvement!is!needed!in!low!scene!illum ination!situations!
!!!!!!!!3.!!Im p ro v ement!in!accu ra c y!o f!t h e !sy ste m!as!ISO!settin g !in cr e as e d!
!4.!Auto!focus!should!ideally!be!a!realtime!action!(or!as!close!as!possible!to!realtime)!so!speed!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
of!calculations!should!be!increased!
!!!!!!!!5.!!Im p ro v ement!in!the!c a lcu la tin g !a lgo r ith m!to!elevate!re lia b ility!
A!more!dense!samp ling!lattice!of! photosites!for!the!cursor!was!developed!to!increase!sensing!sensitivity!
and!accuracy!over!a!wider!range!of!scene!illumination!and!camera!ISO!settings.!!The!cursor!size!can!be!
adjusted!to!accommodate!the!specific!AF!needs!of!a!given!scene!and!situation.!!!
37!
It!can!range!across!the!im age!p lane!according! to!the!discrete! manually!“Selectable!AF!Points”!outlined!in!
Figure! 45.! ! T he re ! are! 87! positio n s! horizo n ta lly! (cov er ing ! 88% ! of! the! image ! widt h) ! and! 65! positio n s!
vertically!(covering!100%!of!the!image!height)!for!th ese!selectable!AF!points.!!This!ensures!very!precise!
auto!focus!operation.!
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Figure&45$ Showing$the$disposition$of$the$discrete$location s$which$is$manually$selectable$
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13.4& &&&Comparison&of&EOS&R&Lens-Camera&System&with&EF&Lens&and&
DSLR!
A!sense!of!the!significant!compactness!that!the!EOS!R!camera!system!can!offer!is!shown!in!the!outline!
drawing!of!Figure!46!which!compares!it!to!the!C an o n !E O S !5 D !Mark!IV.!
!! !!!!!!!!!!!!!!!! !
Figure&46! Outline$drawing$of$a$new$EOS$R$camera$system$(lower)$compared$to$an$equivalent$
Canon$EOS$5D$Mark$IV$camera$(upper)$
The!EOS!R!system!has!a!flange!focal!distance!of!just!20mm,!a!distance!that!was!carefully!optimized!to!
support!the!optim al!op tical!con dition s!pro vide d!b y!a!sh ort!ba ck!fo cal!dista nce !an d!the !mechanical!
rigidity!needed!to!reliably!support!a!heavy!lens.!!
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A!more!dramatic!illustration!is!shown!in!Figure!47!—!which!effectively!conveys!how!the!new!lens!and!
mount!have!very!effectively!shortened!the!overall!length!of!the!lens-camera!system.!
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Figure&47$ $Showing$the$RF24-105mm$F4$L$IS$USM$lens$m o u n te d $to $th e $firs t$EOS$R$cam era$(right$
side$of$picture)$side$by$side$with$an$equivalent$EF$lens$on$a$Canon$EOS$5D$Mark$IV$camera$(left$side)$
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40!
14.0&&&&&&SUMMARY!
The!EOS!system!is!hugely!established!across!the!globe!and!continues!to!move!in!new!directions!—!as!the!
lines! betw e en ! still! an d ! mo t ion ! im a gin g ! bl ur! and! as! lens-camera! image! quality! steadily! increases! with!
every!generation.!!Applications!of!still!and!motion!imaging!have!seen!extraordinary!advances!at!all!levels!
—!from!amateur!all! the !way!to!the!highes t! p rofe ss ion als.!!Collectively,! a es the tic! a sp irat io ns !and!cr ea tiv e !
ingenuit ie s!of!t h e!end!users!are!esca lat in g!—!and!the!bar!continues!to!be!elevated!in!requirements!for!
both!image!quality!and!operational!freedoms.!
The!recognition!that!all!that!is!best!about!the!EOS!system!must!be!supported!into!the!future!is!tempered!
by!an!acknowledgement!that!new!design!options!needed!to!be!opened.!!!!The!new!EO S!R!system!was!
spawned! by! the! vast! accumulation! o f! E OS! system! expe riences! over! the! past! decades,! by! accelerating!
technologica l! advances! in! optics ,! image! s en sors! and! digital! image! processing! over! more! recent! years,!
and! by!a! growing!recognition!that!ongoing!enhan cements!to! the!system! would!require!m ore!degrees!of!
design!freedom!for!lenses!and!cameras.!!!
A!long!examination!by!Canon!R&D!and!Lens!Development!groups!—!on!both!the!optical!and!camera!side!
—! concluded! that! optics! was! central! to! a! new! future! strategy.! ! In! the! context! of! the! digital! camera,!
Moore’s!Law!remains!amazingly!resilient!from!its!first! promulgation!at!the!end!of!the!1970’s!—!there!as!
yet! seems! no! end! in! sight.! ! As! a! conseq u e n ce ,! digital! cam e ra! proc es sin g ! has! bene fite d ! to! an!
extraordinary! level! —! as! testified! by! the! h uge! range! available! today,! their! continuing! performance!
elevations,!and!their!steadily!decreasing!size!and!weight.!!!!It!must!be!anticipated!this!will!continue .!!!
Lenses,! on! the! other!hand,! enjoy! no!equivalent! technological! stimulant.! ! !! The! sciences! of!optics! and!
optomechanics! advance! methodically.! Yet,! the! dictates! of! higher! optical! performance,! greater!
flexibilities!in!o pe ratio na l!s pe cific a tio n s,!and!the!in t ra cta b le !constraints!o f !size!and!w e ig h t!of!lenses!a re !
pivotal!to! supporting! future!prospects!in! imaging.! ! EOS! R! system! was! born!on! the! basis! of! decisively!
removing!so m e !con strain ts!on !lens!d esign s.!
Central!to!the!new!EOS!R! system!strategy!was!the!recognition!that!the! large!54! mm ! diameter! of!the! EOS!
system! w o uld!continue!to!pay!optical! dividen ds!far!into !the! future.!!B ut!the! 44!mm!flange! back!distance!
had! surfaced! as! a! constraint! whose! time! had! come! to! be! dealt! with.! ! Significantly! shortening! this!
distance!would! yield!immediate!new!degrees!of!freedom!in!optical!design.!!But! this,!of!necessity,! would!
have!to!be!balanced! w ith!rigidity!of!the!new !mount,!ease!of!attaching!and!detaching!lenses,!durability,!
dust! and! drip! resistance.! ! ! In-depth! design! reviews! within! Canon! yielded! the! new! RF! lens! mou n t! —!
preserving!the!54! mm! in ne r! diameter!while! significantly!shortening!the! flange!back!to! 20!mm.!! Now,!
positioning!of!large!diameter!lens!elements!m uch!closer!to!the!image!sensor!(especially!the!full!frame!
sensor)!would!support!an!imp ortant!enh ancem en t!of!image!quality.!
This!paper!has!discussed!details!of!the!new!RF!lens!mount.!!!The!advanta g es !of!this!ne w !moun t!design !
are! immed iately! evident!in! the!designs! of!the!first! fo ur!lense s!of!the!RF! lens!family!—!as!outlined! in!this!
paper.!
41!
