is there a limit to how low-powered you can go?

[dc509]

How do you work out the best low-powered EP focal length that will suit your scope? e.g. I have a C9.25 - is there a sensible limit to which EP will give me the best wide field/fastest view? I already have the 6.3 focal reducer - again, is there an optimal EP for the wide views if I'm using the FR? There are obviously a number of EPs in the low 30mm's, but also a small number in the 40's - I have seen many comments about high power EPs and how they only suit certain scopes/FLs/seeing conditions. Is the same true at the other end of magnification?

d

[brianb]

The focal reducer doesn't help at all - in fact it restricts the field more than the baffle tube ... And the relatively large central obstruction in an SCT causes issues with low power / large exit pupil / wide field applications. My favourite low power eyepiece in my 11" SCT is 40mm Meade series 5000 Super Plossl giving x70 ... but I need the "large SCT thread to 2 inch" visual back to get the full value from its 60 degree apparent field, the C9.25 does not have this option.

A short focus apochromatic triplet or ED doublet refractor of 80 to 100 mm aperture equipped with a premium eyepiece suited to the exact focal ratio of the scope makes a great low power wide field instrument. For a wider field still, 10x50 binoculars.

[dc509]

I suspected as much - many thanks. Think I might save up for a 31mm and leave it at that!

d