Afocal photography - Solar system only?

[Marios (Marios)]

Hi all

I recently purchased a Baader Zoom to do some photography of the planets, moon. I'm curious to know if EP's are used for DSO's or Nebula or are these types of objects best done via Prime focus?

[raymo]

DSO's range in size from too large to fit into the field of view of almost any scope's prime focus, and hence have to be imaged with a camera
piggy backed on the scope, to very tiny, and hence needing high
power EPs and a long focal length scope to obtain a reasonable size image.
raymo

[Legin (Nigel)]

Afocal may work for some brighter objects however prime focus is much better. You loose a bit of light with afocal. Prime focus is the way to go if you have a choice. It will give brighter images and allow for faster exposures. If you need high magnification you can use a Barlow.

[Marios (Marios)]

Originally Posted by Legin

Afocal may work for some brighter objects however prime focus is much better. You loose a bit of light with afocal. Prime focus is the way to go if you have a choice. It will give brighter images and allow for faster exposures. If you need high magnification you can use a Barlow.

Yes there is always the barlow to get things a little bigger, does the Barlow effect the F ratio of the scope?

Thanks everyone for the input.

[raymo]

A barlow supplies several benefits. The first is that a 2x barlow doubles
the focal length of whatever scope it is used with, reducing optical
aberrations that most scopes suffer from. Secondly, it improves the eye relief of the EP that you are using, which in the case of some short
focal length ones, is very welcome. Thirdly, it effectively doubles your
available range of magnifications. It is especially useful with
achromatic refractors, which suffer from chromatic aberration.
There only a few possible downsides; namely, it will make a fast scope
slow for imaging; a poor quality one can reduce the quality of your
viewing or imaging experience, and lastly, it makes the optical train
physically longer, which doesn't matter when using the scope visually,
but can cause a heavy camera to sag somewhat, so that it's sensor is not perpendicular to the light path.
raymo