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Thread: Large format Astrophotography

  1. #11
    Corran's Avatar
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    Re: Large format Astrophotography

    I will try my various fast 4x5 lenses when I can get a camera on a scope. I have several f/2.8 lenses. And f/2.5, or even f/2 that covers a 4” square.
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  2. #12
    Steven Ruttenberg's Avatar
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    Re: Large format Astrophotography

    Reason for wanting to cover 4x5 at minimum is for research. Using glass plates provides a fairly stable medium to make measurements once scanned in.

    Plus the detail from a 16in Astrograph would blow away any lens for large format. But the image circle is about 50mm. Need to find a way to triple that without needing a 20 hour exposure.

    I am also interested using Tmax and other be film for tricolor and LRGB images along with the standard Halpha OIII, etc combinations. Of course using slide and color neg film will be problematic as a one shot color.

  3. #13
    Corran's Avatar
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    Re: Large format Astrophotography

    I think you just need a bigger scope .

    I have the elements of a 24" f/6 lens (~100mm aperture) here that covers 8x10. Apparently a popular lens to convert/build into a scope, from what I have read online.
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  4. #14

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    Re: Large format Astrophotography

    Those of you who are doing this... how are you focusing the LF cameras? Are you marking infinity during the day?

  5. #15
    Steven Ruttenberg's Avatar
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    Re: Large format Astrophotography

    Focus on a bright star like Sirius or another depending on time of year. Unlike digital where you can let the computer focus you to FWHMbfor pinpoint stars you have to rely on your gg, eye loupe and skill.

  6. #16
    Steven Ruttenberg's Avatar
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    Re: Large format Astrophotography

    Quote Originally Posted by Corran View Post
    I think you just need a bigger scope .

    I have the elements of a 24" f/6 lens (~100mm aperture) here that covers 8x10. Apparently a popular lens to convert/build into a scope, from what I have read online.
    That is 610mm focal length so that should make for a fine scope. My 102mm shown in pics is a 812mm focal length.

    I say give a try.

    I have the advantage using a guide scope and guiding program like PhD2 to accurately guide for a very long time. Like all night for 8-10 hours of imaging each night. For an LRGB would take 4 nights for tricolor 3 nights. And of course, however many nights depending on filter combinations desired.

  7. #17

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    Re: Large format Astrophotography

    Astrophysics !!!! long wait time for the scope ? and u can always push the film, something I've done shooting star trails with the 8x10. Acros would have helped with reciprocity
    notch codes ? I only use one film...

  8. #18
    Drew Bedo's Avatar
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    Re: Large format Astrophotography

    Quote Originally Posted by Corran View Post
    I'm picking up a Celestron C8 next weekend. Plan to try some wide-field images with 4x5 strapped on the back.

    Telescope won't even cover my full-frame sensor. Why not just use your LF lenses? What do you want to photograph? I plan to use my 250mm f/5.6 Zeiss, maybe Nikkor 450mm f/9.
    Take a look at using the "Eyepiece Projection" technique as a way to cover your format. As I posted, I have used it with an unsophisticated rig many years ago. I lashed it together in my garage. The 'scope was a B&L Zoom Spotting scope and the camera was a Speed Graphic.

    With this method, the telescope with eyepiece mounted is first focused on the subject just as you would if using it visually. Then the camera body, without a lens mounted, is mounted behind the eyepiece at a distance where the image circle covers the format.

    I have wanted to do this again, this time with a C-90 and a TravelWide body, but life issues have interrupted projects like this.
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  9. #19

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    Re: Large format Astrophotography

    Drew, if the current C-90 is the astigmatic dog that the two (one purchased, the other a warranty replacement) I've had were, it won't do at all for astrophotography.

    To be fair to Celestron, I got dog 1 in 1978 and dog 2 in 1983 after I realized that there was a warranty. The current one may be an improved design. The ones I had are the worst and next-to-worst lenses I've ever tried to use.

  10. #20
    Steven Ruttenberg's Avatar
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    Re: Large format Astrophotography

    Quote Originally Posted by Fred L View Post
    Astrophysics !!!! long wait time for the scope ? and u can always push the film, something I've done shooting star trails with the 8x10. Acros would have helped with reciprocity
    I got 120 sheets of Acros!

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