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  1. #1

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    Sep 2009
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    Looking for big, fast lens

    An inexpensive one at that!
    I know I'm asking for much, but I have an astro project idea for a fixed focus (infinity) 4x5 camera housed in a steel tube.

    The faster the better, and coma will be an issue when shooting stars.

    Right now I am leaning towards a Tele Optar 15" f/5.6.
    I have heard that it was a pretty sharp lens.
    How well do you think it will perform wide open?

  2. #2
    EASmithV's Avatar
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    Aug 2008
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    At infinity, I imagine it would work fine. I look forward to seeing your eventual results.
    www.EASmithV.com

    "The camera is an instrument that teaches people how to see without a camera."— Dorothea Lange
    http://www.flickr.com/easmithv/
    RIP Kodachrome

  3. #3

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    Ok, thanks. It will be a while, though. I'm going to have to experiment a lot to find infinity.

  4. #4
    thebanana's Avatar
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    It's just beyond the furthest star on the left
    "While you're out there smashing the state, don't forget to keep a smile on your lips and a song in your heart!"

  5. #5

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    Jan 2008
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    Perth Western Australia
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    russian 300mm f 4.5 huge, fast, cheap, copy of zeiss i think on fleabay approx $30

  6. #6
    Maris's Avatar
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    Look for projector lenses on the 'bay. Many of the episcope or edpidiascope lenses were made to combine long focal length and wide aperture. Optical quality tends to be moderate rather than outstanding but prices can be low.

    I got a nice 450mm f4.5 Wollensak triplet for $23 and passed up a fascinating 300mm f2.0 (!!) because the seller wanted a few hundred for it.
    Photography, the word itself, invented and defined by its author Sir John.F.W.Herschel, 14 March 1839 at the Royal Society, Somerset House, London. Quote "...Photography or the application of the Chemical rays of light to the purpose of pictorial representation,..". unquote.

  7. #7

    Join Date
    Sep 2009
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    Jacksonville, FL
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    I found a Beseler opaque projection lens on ebay, and clicked the "buy it now" button. It has a 5" aperture, and 18" focal length. That should be plenty enough to grab the faint stars.
    I don't imagine it has good color correction, but at 480mm, this might not be an issue.
    How would I go about finding the image circle when it arrives?
    Aim it towards the sun and a white poster board?

  8. #8

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    Oct 2008
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    In case it doesn't work, I've got an(either an 18 inch or 24 inch) kodak aerostigmat F6.3 at the house from an old U2 camera (or so I'm told) the glass is in decent condition, but it has no shutter. I would entertain offers.

    Oh, and I think it's radioactive.

    *Edit*- I'm told they're optimized for infinity focus, though I wouldn't know- I haven't built a big enough camera to hold it yet.

  9. #9

    Join Date
    Jan 2008
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    I saw a set of glass from an aero lens (not Kodak, B&L maybe - try a search for "aero" in camera&photo) on ebay the other day. No barrel but if you're looking to home brew something anyway...

  10. #10

    Join Date
    Sep 2009
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    Jacksonville, FL
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    The projector lens arrived today, and as luck would have it the 3rd 1/4 moon was out in the late afternoon for an infinity focus test.
    I could barely stretch my arms far enough to reach focuswuth the beast, but It looked good through my shakey hands, anyway. It looked to me like a 3x magnification, so I believe it is the 18" focal length.

    I guess my first order of business is to mock up some heavy shipping tubes or pvc to dial the focus in.

    If it doesn't work well as a camera lens, It will end up as a wide field telescope.
    Any ideas for source for a yellow filter?
    I have a strong feeling that it will not focus violet correctly



 

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