Whats the lowest power I can use

[blinky]

Can somebody tell me how to work out what the lowest power eyepiece I can use in my 8" SCT - either at native F10 or with the F6.3 reducer? I'm thinking of exit pupil size and field stops etc. Basically for the past 5 years i have been more or less totally imaging but have now dedicated my SCT to visual and am wondering if I should sell my 2" 42mm EP as it wont be any use:confused:

[pete_l]

I'd say give the 42mm a try. if the views please you then keep it.

[Merlin66]

Working on a 6mm exit pupil...200/6 = x 34 magnification

This would be equivalent of using a 2000/34 = 58mm eyepiece!

I find the 32mm to be a good realistic compromise with the C9.25/C11....

Wide angle type eyepieces won't change the exit pupil but allow more sky to be seen

[CGolder]

Hello, i used to have problems getting focus in some 2" eyepieces with a reducer due to travel, personall i have used without a reducer a 55mm plossl and use my 41 panoptic without issue so should be fine

Sent from my A101IT using Tapatalk

[Ags]

Exit pupil is EP focal length divided by focal ratio, an easy calculation for an F10 SCT! So the 42mm would give a 4.2mm exit pupil, which is definitely not too large unless you are not dark adapted.

If your 42mm is wide angle, I don't think you need to bother with a reducer - it won't let you see any more sky.

[Mr Spock]

My 42mm works great with the C9.25 and gives the maximum field size available.

Forget the reducer. It may lower the f/ratio but can't make the field wider due to the size of the SCT baffle tube. Most reducers have a restricted field stop anyway.

[blinky]

Cheers, thanks guys - guess i need to get out and use it!