Focal Reducer and or 2" eyepiece

[Woolfy]

Ok I have a new CPC SCT 925 and want to maximise the FOV. I've been on the FOV FLO tools page and input the relevant info BUT there is no box to check to say what eyepiece type I have I.e. 1.25" or 2" so. Would a focal reducer and a 2" EP work or should I just stick with 2" EP.

Looking to get the Baader starter set.

[michael.h.f.wilkinson]

The focal reducer allows you to get the max FOV out of 1.25" EPs. However, it has an image circle no larger than about 28mm (the 0.63x, that is). This means 2" EPs show severe vignetting. I switched from a focal reducer with 1.25" EPs to a 2" visual back, and some serious UWA EPs, and never looked back. The only thing I kept the focal reducer for was for imaging purposes.

[MarsG76]

as long as you don't go below the minimum useful magnification with your eyepiece and reducer combination, I don't see why you cant use both.... of course going the 2" way is more expensive, so If on a budget a 40mm eye piece and a f6.3 reducer will do the trick, otherwise, from what I read the TV 32mm 2" eyepiece gives nice wide sharp views... with a reducer I imagine it would be just as good, just with a even wider field.

[Tonynexevo925]

+1 for 2" route and I find the baader clicklock and Hyperion. EPs excellent in the 9.25.

FR if you want to start imaging with the 9.25.

Plenty of threads on here discussing this subject - have a good read before making a purchase.

[michael.h.f.wilkinson]

as long as you don't go below the minimum useful magnification with your eyepiece and reducer combination, I don't see why you cant use both.... of course going the 2" way is more expensive, so If on a budget a 40mm eye piece and a f6.3 reducer will do the trick, otherwise, from what I read the TV 32mm 2" eyepiece gives nice wide sharp views... with a reducer I imagine it would be just as good, just with a even wider field.

The field will not really get wider, due to vignetting. You are right that the 2" route is more expensive. A 32 mm Plössl from TV is a 1.25" with maximal image circle, which can certainly be used with the reducer (effectively becoming a 50.8mm Plössl. A 40mm Aero should give the same true FOV, but with a 4mm exit pupil, rather than 5mm, and a much wider apparent FOV.

[ollypenrice]

The key message is, don't do both. (ie buy 2 inch back and accessories and focal reducer.) The baffle tube imposes a limit which makes using both together a waste of time.

Olly

[michael.h.f.wilkinson]

Even with a wider baffle tube (like in a C14) the standard focal reducer would not give a wider image circle. Its front lens admits about a 48mm image circle. Multiply that by a factor of 0.63, and you have you 28mm image circle.

[John]

The SCT is not really a wide field scope whatever you do to it.

Fortunately there are a lot of DSO's that will fit comfortably within a 1 degree true field. For those that are larger, you either view them in sections or get a low cost wide field scope