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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!
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