Here's an example of a comparison of mirrors of similar diameters: The first is a 6" (~150mm) of 2000mm focal length. With a 40mm eyepiece, it yields 50x and an apparent field of X. The second is also 6" dia., with a focal length of 1000mm. Using a 20mm eyepiece with an apparent field identical to the 40mm used above, it also yields 50x and an apparent field of X. Brightness is identical at identical magnifications. (determined by aperture, remember?) The views are identical except for one thing: The diffraction-limited area of the focal plane for the first example wil be larger than the second. It is optically a better telescope. A secondary benefit is that higher powers are achieved with the longer-focal length scope given the SAME eyepiece. Better eye-relief, a more comfortable view. Longer is always better unless there is a specific need for shortness. As a personal note, it took me 20 years to "come-around", Brent has known this for decades. Consider him the "Yoda" of local optical gurus, I'm more of a Han Solo (a *good-looking* scoundrel in the right place at the right time) Gee, Brent, I hope that nickname doesn't stick! ;) C. __________________________________________________ Do you Yahoo!? Yahoo! Tax Center - forms, calculators, tips, more http://taxes.yahoo.com/