focal reducer for visual observing?

[sky_hawk]

I have a Celestron 6" Schmitt with focal length 1500mm (f/10). Would a focal reducer be a good observing investment? Could I still use my 2" star diagonal?

[DavidLee]

Yes & Probably.

A focal reducer is right up there on the list of priorities as a couple of HIGH quality eyepieces as far as I'm concerned. I have 2 for my 12" SCT. There's a tiny screw-in that came with the scope for f/5. It's NOT the type that screw onto an eyepiece, which I wouldn't recommend. It's just a small one that screw into an adapter on the visual back. Works great for visual work....not so good for photography.

I also use a full-size f/6.something-another. It's actually manufactured by Celestron & my scopes a Meade....but I think they are pretty much standard sizes. It works equally well for visual & photography, since it's full-size. I also think this bigger size passes more light, but I'm sorta comparing apples to oranges...since the small one is a different ratio.

On this big scope, even the f/6.something-another often provides a smaller FOV than I would like, when photographing extended nebulae.....so I sometimes am stuck with the tiny f/5 one, which vignettes a bit. On your 6" though, which is exactly 1/2 of my focal length, I would think you'd do best with something around an f/6.5-f/7.....unless you like REALLY wide FOV's.

This will make your visual experience quite a bit brighter & make photography quite a BUNCH brighter.

Go ahead & save your pennies for a good one though. Just like a low-quality eyepiece, you'll find that a cheap focal reducer screws up the image so bad that you won't even use it. New ones can be found for $100----give-or-take $20 or so.

As a little bonus, a focal reducer effectively doubles the amount of eyepieces you own also. So you'll save money there.

[sky_hawk]

Hello DavidLee,

I think you have confirmed the reducer is a good idea. I am new at this and have had my c6 about 6 months. I do read a lot and make some calculations. My low power lens is a 40 mm Vixen LV w/AFOV of 42 deg for a 37.5X and RFOV of 1.12 deg. Haven't had a chance to do a star drift for confirmation of this RFOV. Where things got interesting is when I plugged in f6.3 for a focal reducer (from my f10). The magnification calculates as 23.6X (near the minimum, per Celestron) AND the RFOV jumps up to 1.78 deg. This comes with a nice uptick in exit pupil diameter. I am not considering photography at this point, just mastering (well adequacy anyhow) star hopping.

Thanks for the feedback.