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Thread: Lenses giving pinpoint star images across a 37mm x 37mm CCD

  1. #1
    BernhardS
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    Lenses giving pinpoint star images across a 37mm x 37mm CCD

    Dear forum members,

    a friend pointed me to this forum, telling me this is the best place to get advice on the following.

    I am looking for high quality lenses for a cooled camera containing a Kodak KAF-16803 sensor (37mm x 37mm, pixel size 9 mu square). The lenses need to have back focus of at least 55mm from the point of mounting. If part of the lens protrudes into the mount then it should do so by at most 25mm (otherwise I get problems with the filters that go in between lens and CCD).

    The sensor is b/w, it does not have a Bayer array. Hence there is no spatial low pass filter in front of the sensor, and thus the requirements on the lenses are somewhat higher than what one might expect from a 9 mu pixel size.

    I am interested in lenses with focal lengths roughly in the range of 50mm to 150mm that can give pinpoint star images in astrophotography, across the whole frame, at large apertures, when focussed to infinity. Distortion does not matter, flare is not a major issue, vignetting should ideally be small, but most importantly the other optical errors need to be small (coma, chromatic abberations. field curvature...). The lenses need not have a shutter. Focussing should be possible, but a small focussing range around infinity suffices.

    I have so far tried a Mamiya 645 80mm f/1.9. The results in the corners are OK-ish but not really good, unless it's stopped down to f/5.6. I have also tried a Canon EF 200mm f/2 with much better results, although that lens is of course not made for a 37mm x 37mm sensor.

    My friend recommended to look into Schneider-Kreuznach digitars und Rodenstock APO sironars.
    Starting from this, I looked around on the web and found the following possibilities:

    Rodenstock HR Digaron-S (Apo-Sironar digital HR) 100mm f/4 with Focus-Mount, or HR Digaron-W 50 mm f/4 with Focus-Mount

    Schneider-Kreuznach Apo-Digitar 4/60

    Zeiss Sonnar T* 4/180 ZV

    ... Distagon T* 4/40 IF CFE

    Distagon T* 4/50 ZV

    Planar T* 2/110 FE

    Planar T* 3,5/100 CFi

    Planar® T* 2/110 FE

    Makro-Planar T* 4/120 ZV

    Distagon T* 3,5/60 CFi

    Planar T* 2,8/80 CFE

    Distagon T* 2,8/50 FE

    HASSELBLAD HC 2.2/100 or HC 3.2/150N

    Mamiya 645 A 2,8/200 mm APO or A 2,8/150 mm N

    I would be happy for any recommendations, or pointers to test results.

    Best regards
    Bernhard

  2. #2
    Optechs Digital
    Guest

    Re: Lenses giving pinpoint star images across a 37mm x 37mm CCD

    Dear Bernard,

    I think you will find that few have much expertise in what you are looking for . However I believe it would be hard to do better than the lenses offered by Schneider and Rodenstock. These lenses are available in focus mounts and their specifications are readily available on their respective websites. You will also be able to find the focal to flange distance as well on these sites as it sounds like this will be a custom job.

    I think a lot of us are probably very interested in taking a look at this cooled camera you have as well as a sample or two of the type of work you are doing. At least for me, this sounds like something i would like to know more about. Can you post a picture or two?

    Best regards and good luck with your quest.

    Paul

    Quote Originally Posted by BernhardS View Post
    Dear forum members,

    a friend pointed me to this forum, telling me this is the best place to get advice on the following.

    I am looking for high quality lenses for a cooled camera containing a Kodak KAF-16803 sensor (37mm x 37mm, pixel size 9 mu square). The lenses need to have back focus of at least 55mm from the point of mounting. If part of the lens protrudes into the mount then it should do so by at most 25mm (otherwise I get problems with the filters that go in between lens and CCD).....


    Best regards
    Bernhard

  3. #3
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    Re: Lenses giving pinpoint star images across a 37mm x 37mm CCD

    Bernhard,

    You may want to keep an eye out for Agiflite and other aerial camera lenses. These are optimized for infinity and mounted on boards that can be customized for a one-off camera like yours.

    I would start by searching for "aerial" at surplusshed.com. They have a few in stock and should be able to answer your questions about back focus and clearance.

    Out of the list you posted, the Planar 3.5/100 and Mamiya 2.8/200 would be my top choices, however I don't have any experience with most of the lenses.
    You should also consider the Planar 2.8/150 (which was also sold for aerial cameras).

  4. #4
    Senior Member Lars's Avatar
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    Re: Lenses giving pinpoint star images across a 37mm x 37mm CCD

    Lenses specially designed for minimal coma must be a priority? There's an article about the design of the Nikkor 58/1.2 here:
    http://imaging.nikon.com/products/im...kkor/n16_e.htm
    Monochrome: http://mochro.com

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