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Hi Scott:
I think what you're running into is the
"high magnification leads to mush" phenomenon. Even with unattainably perfect
optics, the atmospheric turbulence ("seeing") results in a gradual loss of
definition as you increase magnification. Since you're starting with a 2000 mm
focal length at prime focus, when you start doing eyepiece projection, you're
going up to gigantic amounts of magnification. You'd best get above the
atmosphere for that! My best film shots of the moon have been made at prime
focus or 2x Barlow. My 2 cents....
Bert
----- Original Message -----
Sent: Monday, 03 September, 2001 9:24
AM
Subject: [APML] Lunar Photography
I have just experienced one of the more
frustrating lunar photography sessions of my short life and have a couple of
questions about the whole experience.
I have been using an 8" Meade
LX-200 and a Canon ELAN II (35mm SLR) doing prime focus (camera mounted
directly to the telescope with out an eye peice) and am finaly starting to get
some good results (for your viewing pleasure some of the more recent shots can
be found at http://www.manetheren.net/night). Focusing was a little off at first, and then I had some
issues with camera shake (the mirror wasn't tripping up prior to shooting) but
finaly worked those out.
So I figure I'm ready to try some eyepeice
projection. I throw in a 26mm super plossl (f/28.4), and right off the
bat I notice I can't find that "sweet spot" in the focus where everything is
crystal clear. As my camera's meter is fairly sensitive, I bracket some
of these shots on focus instead of shutter speed.
Then I decide to go for the gusto and throw in
a teleview 4.8mm Nagler (f/198.5). I couldn't even come close to getting
things in focus. Same results with my 9.7mm Super Plossl (f/94.3).
Everything is just a fuzzy gray and brown blur. I tried extending my
tele-extender all the way out and all the way back in. Didn't make a
diffrence.
I guess what I'm realy wondering is if those
focal ratios (and attendant maginifcations) are simply beyond the ability of
my scope and camera to handle.
Thanks,
Scott
"God does not play dice with the universe; He
plays an ineffible game of his own devising, which might be compared, from the
perspective of any of the other players, to being involved in an obscure and
complex version of poker in a pitch dark room, with blank cards, for infinite
stakes, with a dealer who will not tell you the rules, and smiles all the
time." -- Gaiman and Pratchett
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