Celestron 0.7x focal reducer for Celestron 11" EdgeHD scopes and optical tubes


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This Celestron EdgeHD 0.7x focal reducer turns your 11" f/10 EdgeHD telescope into a full f-stop faster f/7 scope, increasing your photographic field of view by 43% and cutting your deep space exposure times in half . . .
Our Product #: 8311HD
Celestron Product #: 94241

Product Description

This Celestron EdgeHD 0.7x focal reducer is a 5-element lens system that converts your 11" f/10 EdgeHD scope or optical tube into a fast f/7 optical system. It threads directly onto the 3.25" rear cell threads of all 11" EdgeHD optical tubes, in front of your imaging equipment. It increases your photographic field of view by 43% to better capture wide field images and cuts your deep space exposure times in half, all the while maintaining the flat-field performance of the native Edge HD optical design.

This Celestron EdgeHD reducer has high index optical elements, including exotic extra low dispersion rare-earth Lanthanum elements, to provide high contrast viewing while minimizing chromatic aberration. All air to glass lens surfaces are fully multicoated for maximum light transmission and color correction. Lens edges are blackened to minimize internal reflection and maximize image contrast. Large diameter lens elements, up to 60 mm clear aperture, ensure that the optimized image circle remains at a generous 42mm for use with large CCD sensors.

The system maintains the same back focus at its faster f/7 focal ratio (nominally 146mm from the rear flange of the reducer to the image plane within your camera) as it has when your 11" scope is used at f/10. This generous back focus accommodates a wide variety of cameras and imaging accessories.

Threading the CNC machined aluminum housing reducer directly onto the rear cell reduces mechanical vignetting and allows for use with larger (full frame) sensors and off-axis guiders. The CNC machined aluminum housing assures precise spacing and alignment of the optical elements. Threaded metal covers on both sides of the lens assembly protect your investment from dust and scratches. The housing duplicates the rear cell threading of the scope body so you can use of your existing EdgeHD T-adapters with or without the reducer in place.

Tech Details

Weight 49.6 oz
Warranty 2 years


Review by:
The focal reducer for the 11" EdgeHD scope is quite a large piece of optics. It's installed on the back of the scope after unscrewing the normal back end piece that is normally mounted there and just screwing it on. The normal end piece is then screwed onto the 0.7 reducer and everything works as normal. It does have some weight and extends all your back end equipment out a few inches, so you will want to check your scope balance after putting this on.

I put my diagonal on and put my 41mm Panoptic eyepiece in and was just floored with the view of the waxing moon. The full moon will fit in that view perfectly and I then put my Canon camera with full size sensor on and also confirmed the whole moon disc will be seen with a lot of room to spare. This was my goal and I'm pretty happy with the view and operation. Future nights I will start using it for photos when the moon doesn't disappear behind the neighbor's tree like it did on me the other night!
(Posted on 9/9/2019)
Review by:
This is a very large piece of glass and heavy. It is much larger than the older 0.63 focal reducer from Celestron and Meade.

It screws directly on to the OTA and is very large diameter. The effect of the optic is to take the f/10 Edge down to f/7 and maintain the edge flat stars across the field. I have confirmed with plate-solving software that the focal length is about 1960 with this installed. That just abour f/7. I've also confirmed with imaging that stars in the corners stay round.

The only thing you have to be sure of is to get whatever spacers necessary to place the imaging sensor at exactly the right back distance from the threads of the OTA. There is just enough room for a motorized focuser, a filter wheel, an off-axis guider, and the camera. That plus a small spacer puts the image plane in the correct zone. If you are too short or too long, you will get distorted stars. So please follow the directions and you will not be disappointed. (Posted on 1/2/2019)
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