Quote:
Originally Posted by ozskywatcher
Hi,
Just wondering if anyone could help with the following.
I have been having some fun webcasting the Moon using a Phillips webcam and a 8 inch Celestron telescope. Even with a focal reducer, the field of view is way to small for anything else.
I would like to be able to experiment to see if the webcam can be used for things like encounters between the Moon and planets (maybe up to 5 degrees apart). This will need a completely different lens. I was thinking that maybe a 50mm SLR camera lens would work. I would just need some sort of adaptor that would let me attach the webcam to it (as well as a thread so I could stick it on a camera tripod).
I have a 1 1/4inch eyepiece adapter which the webcam is attached to. My pondering was that perhaps I could find an adapter somewhere that lets you stick a 1 1/4 inch eyepiece on a 35mm format camera lens. That way I could just pop the webcam adapter in it and instantly be ready to webcast.
Any suggestions would be appreciated.
Regards,
Paul Floyd.
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Hi Paul,
I'm not sure what field of view an eyepiece would give when used as an
objective...
SLR lenses however are excellent when coupled to a webcam.
I find a 50mm is a great all round lens for just the type of close shave moon/planet encounters you describe.
Also it is a good combo for wide field comet shots.
See here for some of my comet stuff through a 50mm:
http://mywebsite.bigpond.com/astrosteve/neatq4.html
You would need to bodge up an adaptor which would have a T-ring and
a bayonet mount one end and at the other a mogg adaptor.
The spacing from the lens to the CCD face is critical and usually
about 42mm for most SLR brands.
If you get this right then the focus ring distances on your lenses
should still correspond....infinity, 3m etc.
But I must also advise you that you would need to have an IR/UV rejection
filter somewhere in the path.
I used a bodged up adaptor just like this for years until I made a proper
one on a lathe:
http://mywebsite.bigpond.com/astrost...ching_pair.jpg
SLR lenses don't focus IR at the same spot as visible and so if you
have a modded cam and ever do long exposure, some objects will be
blurry or have halos:
See here for a shot of an M-type star with lots of IR out of focus:
http://mywebsite.bigpond.com/astrost...era%20performs:
Steve