rolandlinda3
Carpal Tunnel
Reged: 01/24/06
Posts: 1619
Loc: Crozet VA 22932
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The attachment shows a quick and very rough sketch of our second use of a MallinCAM ProDob B&W camera that was fitted with a low-end fully-manual telephoto lens (5-50mm 1:1.6; 1/3 in. CS). We mounted this arrangement on a monopod with no star pointer. You just aim the camera arrangement, watch the monitor, and adjust the camera in elevation/azimuth to center the area that you want.
We tried this because we enjoy and sometimes teach others about the general features of the Milky Way. The scene could easily be projected for large group.
The results were very pleasing. I had heard of others trying this and recommending it, but we just had not had the chance to do it. While the lens we used is pretty low-end and the manual focus is a bit of a trick, once things are set the view is very good -- rivaling some panoramic photos of the Milky Way, except we are seeing it live.
There are many potential applications since the scene detail is good. The sheer beauty of the dense areas of the Milky Way (both light and dark regions) becomes very obvious. Prominent objects can still be identified, large open clusters are apparent. The only disadvantage is that prominent stars tend to oversaturate. I kept getting lost doing the sketch, which is why I marked the Tea Pot stars (it helped me get re-oriented when I needed to keep one finger on the monitor while sketching). The most interesting feature is the definition of the light/dark regions. My sketch does not do the scene justice but gives you an idea.
If anyone has questions, I cannot answer any about the camera lens or settings. I know nearly nothing about photographic hardware. You would laugh watching me "adjust" the lens. As long as I could get the scene to focus and "go in or out", I did not care about anything else.
Roland
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Jack Huerkamp
Vendor - Waning Moon
Reged: 10/13/05
Posts: 519
Loc: Louisiana
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Roland,
Was the lens set to 5mm, 50mm or somewhsre inbetween. 
Jack
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Orion ED80
Coulter CT-100
Celestron 6" f/8 Refractor
8" Newtonian/Cassegrain on Byers 812 Mount
Classic C-8
Celestron 11" CPC 100 with HyperStar
Tricked-out 17.5" AstroSystems TeleKit
Life Member and ALCOR - PAS New Orleans
 Waning Moon II Observatory
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rolandlinda3
Carpal Tunnel
Reged: 01/24/06
Posts: 1619
Loc: Crozet VA 22932
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Gotta show how dumb I am: it was set so that I was about 2/3 of the way to the widest shot I could get. Never looked at the tiny levers...did it all by feel and watching the monitor. That help? Roland
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nytecam
Post Laureate
Reged: 08/20/05
Posts: 4814
Loc: London UK
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Hi Roland - tried my 8mm fl TV 'C' lens in 'finder mode' perched under SCT corrector plate for wide-angle shot of sky like this marked-up shot in 20s exp covering >120 square degrees of sky. Swapping to longer 58mm f/2 Zenith lens even the form of M51 and other galaxies revealed - amazing for a regular camera lens piggybacked on my SCT 
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Nytecam 51N 0.1W
Meade 30cm LX200+ETX-70+DS-2090+C8+Ha+CaK PSTs SBIG SGS+homebuilt spectrographs
Starlight SXVF_M9/Lodestar/Canon 300D DSLR/Fuji E550
My observatory build-ETX-70 imaging-spectro page
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ccs_hello
Carpal Tunnel
Reged: 07/03/04
Posts: 2805
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Roland,
5-50mm Zoom lens (for video cam or DSLR) is still a lens with focal length from 5mm (very wide) to 50mm.
Using Ron Wodaski's CCD calculator
http://www.astrovid.com/ccd_calc.php
set aperture: 10mm
and f/ratio: to 5
(this yields fl =50mm)
CCD Camera: StellaCAM EX EIA (also a type-1/2" sized CCD)
Press "Recalculate"
It will show telescope focal length = 50mm
Field of View 332' x 443' (5.53 x 7.38 degrees)
The "Red Rectangular Block" shows the sky coverage.
Clear Skies!
ccs_hello
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rolandlinda3
Carpal Tunnel
Reged: 01/24/06
Posts: 1619
Loc: Crozet VA 22932
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Thanks. I confess to just getting the scene I want and sketching. This little lens has no readout, no marks, nothing...so I just guess where I am and look at the star field if I want to estimate FOV. I suppose better lens arrangements have some markers so in-between the "stops" one can actually see where the lens is placed. I just knew I was pretty wide. The challenging part is getting the best focus, since the slightest hair of a touch sends to much of a change. Roland
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rolandlinda3
Carpal Tunnel
Reged: 01/24/06
Posts: 1619
Loc: Crozet VA 22932
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That is a pretty neat arrangement. I have heard of others doing something similar but never saw a picture. The approach can be handy. Thanks for posting the setup and the picture. Roland
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ccs_hello
Carpal Tunnel
Reged: 07/03/04
Posts: 2805
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I am showing some lenses with different image circle sizes.
From left to right:
type-1/4", type-1/2", type-1/1.5", 35mm (135 format)
type-1/4", type-1/1.5", 35mm (135 format) big zoom len
My point:
it does not make sense having a type-1/2" videocam while using a less capable lens (smaller image circle size) not fully illuminate the imaging area.
Clear Skies!
ccs_hello
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rolandlinda3
Carpal Tunnel
Reged: 01/24/06
Posts: 1619
Loc: Crozet VA 22932
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Sense did not have much to do with it. I had a lens...I tried it. I am sure there are better choices and arrangements. Mostly, it was just neat to see the Milky Way wiht definition.
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