Celestron Focal Reducer - #94175 - Celestron say it's not compatible with Edge optics but I have found that not to be the case

[StarGazingSiouxsie]

Hi, 

I bought a Celestron focal reducer / corrector lens part #94175 for my non Edge CPC1100. Celestron say - in bold type no less - that this reducer is not compatible with Edge HD optics. The cost of the dedicated reducer for the Edge optics ( #94242 ) is ~ $200 more than the non Edge version 

Out of curiousity, and to make sure what Celestron say was correct, I tried the non Edge focal reducer part number #94175 on my 8" Edge telescope - and it works just fine. The field of view is expanded as it should be and the clarity to the edge of the view is as clear as when not using the reducer. IE vignetting is minimal / non existent

Has anyone else found this to be true with their Edge and non Edge telescopes? This is significant; the price difference is about $200 between the two reducers and, in my case, the non Edge reducer gives me altitude clearance on the bottom of my Evolution mount whereas using a dedicated Edge reducer ( #94242) would not. 

So if you're in a similar to me, try the non Edge reducer first before spending an extra $200.

 

Siouxsie 

 

Edited September 26, 2020 by StarGazingSiouxsie

[globular]

Interesting.

I guess they mean "not optimal" rather than "won't work at all". But you can't detect any issues? Are you using it visually only or for imaging too?

[StarGazingSiouxsie]

49 minutes ago, globular said:

Interesting.

I guess they mean "not optimal" rather than "won't work at all". But you can't detect any issues? Are you using it visually only or for imaging too?

I think their, Celestron's, wording is enough to make most people think they have to purchase the more expensive reducer. I know I might sound cynical but they are there to make money. The wording from their manaul says "not compatible"

https://celestron-site-support-files.s3.amazonaws.com/support_files/94175 IM.pdf

All I can say is that I tested the non Edge focal reducer (model number 94175) in both a non Edge SCT (Cubble) and an Edge SCT (Celeste) and the viewes as far as I could tell were exactly the same. No discernable diostortion or vignetting etc in the Edge optics.

Apart from the price difference, the other significant aspectt is that the non Edge reducer is much smaller than the Edge version and this fact will be significant for people with Edge optics with single fork mounts (like me) wherein it means that I can probably use the reducer on Celeste without the optical train fouling the top of the mount where the azimuth clutch is.

[globular]

It's great you have both scopes and can try the non Edge reducer on each one and draw your own conclusion. Not cynical at all - very sensible.

I do wonder if you'd notice a difference if you were imaging rather than just visual. And in that case you'd probably use a wedge or a different mount and the size difference would be a moot point too.

However as you are visual and it's working (in fact is better due to the size difference) then that's great news for you and good to know for the future for me too if I ever feel the need / can lay my hands on one.

👍

Edited October 4, 2020 by globular

[Xplode]

For visual there might not be that much of a difference, but for imaging it's a different story.
Remember the old focal reducer is also a coma corrector, the EdgeHD design doesn't have coma so it will correct for something that's not there so most likely it will introduce coma or some other abberation.