A Question - Focal Reducers

[Alkaid]

Possibly silly question...

I have never owned an SCT or Mak and was wondering how the focal reducers work...

If I had a 150mm F12 Mak and apply an F6 reducer, does that make the Mak F6 with new focal length 900mm?

Many thanks!

[ronin]

Not 100% sure but I think you are talking about a reducer for an f/6 scope.

If that is it then there will be another value attached to the specification like 1.6 or 0.85 or something.

If my thoughts are correct, and that number is in the specification, then if it is say 0.8 (example only) then on an f/6 scope the reduction is to 0.8 of the original f number so it is now 6x0.8 so 4.8, the new value makes the scope an f/4.8 scope.

Not sure how well an f/6 reducer would work on a f/12 scope.

[rowan46]

I agree with ronin an f6 reducer is for an f6 scope. you can get reducers for maks. Never tried one but I believe that .6x is the maximum recommended. This would take your f12 down to f7,2

[Alkaid]

Thanks guys - now I get it.  Of course, I was thinking about a 0.6 reducer.  This all makes sense now.

Ta

[alan potts]

I don't know if there are special reducers for Maksutov scopes, I have the 180mmm F15. I also have an F10 SC and the reducer for that (.63 reducer) does not work on the Mak and I always thought it would.

The .63 focal reducer on an SC scope aslo restricts your 2 inch eyepieces to 28mm 68 degree FOV, however you get about you largest FOV with that.

Alan.

[nightfisher]

I don't know if there are special reducers for Maksutov scopes, I have the 180mmm F15. I also have an F10 SC and the reducer for that (.63 reducer) does not work on the Mak and I always thought it would.

The .63 focal reducer on an SC scope aslo restricts your 2 inch eyepieces to 28mm 68 degree FOV, however you get about you largest FOV with that.

Alan.

Alan, why does the reducer not work on the 180 mak, is it just to do with the thread fitting, of an optical issue

[russ.will]

With my potential purchase of an SCT looming, I've been looking at focal reducers from a visual standpoint.

As I understand it, there seems to be two kinds. One that corrects for the curved field of an SCT and one that doesn't although I've ssem the same thing marketed as both - The Antares springs to mind. Chuck the former on a Meade ACF, Celestron EdgeHD or a Mak which is either already corrected (ACF & EdgeHD) or a Mak, which doesn't have that problem in the first place, and it will over-correct.

There seems to be general confusion as to which reducer does what, but the Astronomics page seems to be about as clear as any - Note that Celestron manufacture not only specific reducers for the EdgeHD, but specific variants for each size of OTA.

I've also noted that some discussion surrounds the back-focus distance required between the FR and eyepiece/camera, with multiple claims between users for the same FR. 83-110mm seems the most common range.

I don't now if any of this relates to Alan's Mak/FR issue, or even if it is all true, but it seems to have a ring about it!

Russell

[celestron8g8]

As mentioned above i'm not sure they make a reducer for a Mak but new stuff is coming out all the time . I have a Celestron C8 and i have the f/6.3 reducer which turns my f/10 scope to a f/6.3 with the reducer .