Remove Visual Back
Remove
Adapter Plate
Reducer Lens
Baffl e
Lock Nut
T-Ring
Camera
Focal
Plane
5.75”
146 mm
EdgeHD 9.25”, 11” and 14” – Optimum Back Focus Distance
Figure 1 – Optimum Spacing for EdgeHD 9.25/11/14
T-Adapter
Instruction Manual – Model #94245
.7x Reducer Lens – EdgeHD 9.25”
Your .7x Reducer Lens makes your EdgeHD 9.25” telescope one full
F-Stop faster than at f/10. Photographically this will enable you to reduce
your exposure times by one-half and still capture the same amount of light,
while providing a 43% wider field of view.
Celestron LLC • 2835 Columbia Street • Torrance, CA 90503
Phone: 310.328.9560 • Fax: 310.212.5835
©2018 Celestron • All rights reserved. #94245-INST 03-18
Warranty: Two year limited warranty.
For complete warranty details contact Celestron or visit:
Attaching the Reducer
1. Remove the visual back and adapter plate from the rear of
the telescope.
2. The focal reducer threads directly onto the rear baffl e lock nut
(see Figure 1) of your EdgeHD telescope.
3. Attach your T-adapter (#93646 or #93622, sold separately)
onto the rear threads of the focal reducer.
Camera Spacing
Since optimal photographic back focus of 146 mm is the same
with or without the focal reducer attached, the optional #93646
or #93622 T-Adapter can be used to attach the Nightscape
CCD Camera, DSLR body or any other camera with 55 mm of
back focus.
For best performance, it is highly recommended that you position
your camera as close to the recommended optimal spacing as
possible. It is best to maintain optimal spacing to within 1-3 mm
depending on the size of your imaging sensor. As your imaging chip
gets larger (farther off-axis), maintaining optimal spacing become
more critical. Being inside of focus (too short) tends to affect the
outermost edge of the fi eld of view when using a relatively large
sensor (17 mm or greater). Being outside of focus (too long) tends
to produce elongated star images towards the edge and could run
the risk of running out of focus travel on your EdgeHD optical tube.
In general it is better to be slightly inside of focus than
outside of focus.
Focal lengths for the EdgeHD 9.25” in its native format (f/10), with the .7x reducer lens and with optional f/2 lens assembly.
Telescope Model f/2 Confi guration .7x Reducer Lens Standard f/10 Confi guration
9.25” 470 mm (18.5”) 1,645 mm (64.75”) 2,350 mm (92.5”)
