Celestron f6.3 reducer

[compassrose]

Hi all

Sorry if this isn't in the right section.

I've bought the celestron standard f6.3 reducer for use in my cpc800 when imaging. I wondered if there may be circumstances where it might offer an advantage when fitted to the scope for visual use?

Sorry if its a daft question!!

David

[Adrian]

Hi David

Not daft at all - you can use it for visual if you want a wider view through your 1.25" eyepieces, rather than getting a 2" fitting on the back of your scope and buying a 2" eyepiece.

Just be aware that you cannot get a wider field of view than the scope is capable of and you may get aberrations at the edge of the fov.

Also: I've never tried a reducer myself, but this is what I understand is the case So i may not be 100% accurate here

[Davey-T]

Hi David

I have a Meade 6.3 Focal reducer, basicaly the same thing, I have used it for observing but I think it's designed for imaging allowing shorter exposures and easier imaging all round.

Davey-T

[michael.h.f.wilkinson]

I used my 0.63x reducer quite a bit, until I got my 2" visual back, and went for 2" EPs. It worked fine with my 26mm Plossl I had at the time, and it was sort of OK with the 36mm Plossl, but the view using the TMB Paragon 40mm 68 deg EP is just so much better (and a bit wider), that I have not used my reducer since then.

[alan potts]

Not a silly question at all, I use one on a regular basis. It will work with 2 inch diagonals and Ep's up to 28mm, over that it will vignet. You should get a good FOV with one fitted if you have 2 inch gear. It is also a good way of sealing the tube from dust, leave it in place.

Alan.

[compassrose]

Thanks everyone - what a really helpful forum this is!

[alan potts]

If your F/Length is 2000 and you were able to use a 28mm 2 inch EP with F/reducer that will give you a mag of X45, assuming the 28mm is 68 degree FOV eyepiece then you will get 1.51 degrees of real sky to look at. In simple terms that's 3 times the width of the full moon.

With my scope I can only get about 1 degree, not enough for M45, which you will frame nicely

Alan.

[michael.h.f.wilkinson]

Actually, the most I can get out of my C8 is 1.34 deg True FOV (Paragon 40mm with 68 deg FOV). This corresponds to a 45.6 mm field stop. This is about as big as the clear aperture of the focal reducer, so you cannot gain more than that (still nice) without vignetting.

[Pingster]

I bought one for my celestron 8se which has 2in diaginal. I was very dissapointed as it does not work well in thois situation. Its designed for 1.25" diaginal and eyepieces and when used with such, vastly improves the views FOV and clarity. In 2in the views you see have excess coma and looks 'wrong'.

[michael.h.f.wilkinson]

Do you mean coma when you use the 2" EPs with educer with or without? I must say that without I do not get coma in my 2" EPs, at least not in any obvious way, at the low magnifications used. There is some slight field curvature (the softness at the edge with the Paragon disappears when refocusing). The focal reducer/coma corrector works best at a particular distance for which it has been designed. The standard 1.25" diagonal and the T-adapter piece set the EP and camera at the correct distance respectively. The longer distance provided by a 2" diagonal means that coma is not properly corrected anymore.

[Pingster]

This is the combo i tried tht does not give good results:

8se + reducer + 2in dia + 2in eyepiece (32mm nag and 13 ethos).

If anyone can tell me how i can achieve the correct spacing with my 2in parts thats would be awesome.

[michael.h.f.wilkinson]

A 31 Nagler (which I have) gives really good results without the reducer (all my 2" EPs are used that way). The 31T5 also covers about as big a FOV as you can possibly get (1.25 deg) so there is little point in inserting the reducer.