Posts Made By: Joe Giacalone

John,

it is an issue of what magnification you want and what your
imaging system can handle (i.e. shutter speed).

there is a simple formula for the amplification of your
prime focus using (positive) eyepiece projection:

A = D/f - 1

where D is the distance from the eyepiece to the focal
plane of your camera, and f is the eyepiece focal length.
Multiply A by the focal length of your telescope and you
will get the resulting focal length. Note that the
exposure time goes up dramatically with your resulting f-ratio which is simply the overall focal length divided
by the aperature of your scope. The longer exposure time
leads to a poorer image quality due to the effects of
the atmosphere.

You can also use a barlow to magnify the image (this is
actually negative projection and the formula is a bit
different -- but probably close to what your barlow is
2x, 3x etc)

Hope this helps,

Joe

Wesley,

I continue to be amazed at the quality
of your lunar images. The resolution
in this image may be better than 0.15"
-- amazing! Gassendi is one my favorite
targets. Keep it up!

Joe

Wes,

How did you get your telescope into lunar orbit?

Can you estimate the resolution? (I dont have
time to do this anymore -- but it looks like
you are below 0.1" -- great work)

Joe Giacalone