[APML] Knife edge focusing question

["bert katzung" <katzung1@home.com>]

OK folks, I have a confession to make. I've been pretending to do
astrophotography but it's obvious that I can't be a "real" astrophotographer
until I figure out this knife-edge focusing bit.

I have read everything I could find on the subject, especially Jerry's and
Chuck's articles, and articles on how to make one. But when I put a razor
blade on the back of my Nikon, put the Nikon on the scope, and point it at a
star, I don't see any of the stuff that people talk about. I see a sort of
image of a star through the scope when the KE is not in the way, and I see
the KE when it is in the way. Doesn't seem to matter whether I move my head
or the scope to put the KE over the star. Where is this black bar that comes
across in one direction inside focus and  in the other direction outside
focus?

Obviously, there's some simple thing that I'm not doing, but what is it?
I've never seen anyone do KE focusing, otherwise I wouldn't be asking. (In
fact, I've never *seen* anyone take an astrophoto (film) at all---the only
other local guy who takes pictures is a CCD'er.)

Any help appreciated...

Bert

Bert Katzung
katzung1@home.com
www.astronomy-images.com (all astrophotos NOT KE-focussed)


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