Hi, with this weather, astronomy is becoming a theoretical hobby. Just for grins I did a couple of experiments measuring the peak bandpass for a 2" Baader Ha...
nice work Richard Note that the angles of the rays will change as one moves from the center of the filter to the outer extremities in the typical imaging...
Hi Richard, the test confirmed my decision to place focal reducers after the filter such that the filter is always in the greatest f- ratio light. IMO you need...
here's a bit about relay optics from Bely's book "Design and Construction of Large Optical Telescopes" I have a copy of the book btw and it is pretty darned...
I have been having fun with my home-build SkyCam on every clear night. The original intent was to capture meteors and fireballs. As soon as I began to use it,...
Hi guys I have made a barn door tracker for my DSLR and I have had several failures due to the thing moving when tirning the wheel, however I have adapted a...
try some of the aperture filters for camera lenses. Tokin and B+W Optik are two such producers adorama DOT com is one place I shop for used lenses etc. you may...
We'll I'm using f/1.4 now. I forgot all about the fact that I can stop the CS lens WAY down. ... From: Jesús Navas To: Astroimaging_filters@yahoogroups.com ...
Hi Frank, would the Baader solar film be too dense for your purpose? Be careful with general purpose ND filters, many pass IR. Regards, Richard ... night. The...
I was thinking about that. Baader AstroSolar sheet film has a ND5, but you probably need about a ND 6 or more, so you can stop-down your lens to 5.6or so to...
That is a good idea but I don't know what ND5 means. I'd prefer not to stop down the lens as it would be very easy to knock out the focus. Focusing this lens...
Will it wrinkle easily like a Mylar balloon? Would wrinkles make a difference? ... From: Richard Crisp To: Astroimaging_filters@yahoogroups.com Sent:...
yes and yes make a cell for it so you can stretch it tight then put the camera etc in a box with the only way for light to get it is through the cell with the...
yes and yes make a cell for it so you can stretch it tight then put the camera etc in a box with the only way for light to get it is through the cell with the...
I wonder if my schedule 80 PVC housing is light tight? I just up-loaded 2 pix of the cam in the "files" section in the Black River Observatory folder. ... ...
dunno but spray paint and aluminum foil can make it so.. ... From: Photon Collector To: Astroimaging_filters@yahoogroups.com Sent: Wednesday, January 02, 2008...
ND = neutral density, but perhaps I should say OD = optical density or simply D = density. If the filter has a D=5, that means that the filter has an exposure...
Thanks for all of the great info, guys! I knew I could count on you to help me out. ... From: ssb73q To: Astroimaging_filters@yahoogroups.com Sent: Thursday,...
Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the Astroimaging_filters group. File :...
Astroimaging_filters@...
Jan 4, 2008 4:06 pm
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Hi: Happy new year to all members of the group, I wish you a year full of health, happiness and good seeing. :-)) On the former message, I posted an image of...
Hi, wonders of wonders, the sky cleared for a short time last night so that I was able to compare my low cost Optometric narrowband filters to some other...
Let's hope all these new entries will lower prices all around. Unfortunately Astronomik does not seem to offer clips for 40D or 30d :-( ... klemmhalter.html...
Hi Samir, I hope you are fine. Better temperatures anyway. My guess is the clip filters will fit any Canon DSLR as the lens dimensions have not changed. But to...
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