10 May
2010
10 May
'10
12:17 a.m.
Here's another fun fact-ish tidbit about Cassegrains. If the secondary is 3X, and you move it one millimeter towards the primary, the focal plane will shift aft three millimeters. If the secondary is 4X, moving the secondary one millimeter will shift the focal plane four millimeters. Get it? Sometimes helpful in planning and laying out your imaging equipment stack.