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Thread: Astrophotography with the Travelwide 4x5?

  1. #1

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    Astrophotography with the Travelwide 4x5?

    Just came in from looking at the moon in a little 3 inch f6 reflector. It's still daylight here but it got me to thinking. Has anyone done wide field astrophotography with their 4x5? The 90 is so light it would put no stress on a barndoor mount and the wide field of the 90 mm lens could suffer slightly inperfect alignment. Of course, f6.8 is very slow, and if you stopped down to f16 to clean up the edges that could make for some very long exposures, too long for a barndoor mount to trac accurately. So....Is was just curious if any here had used their 4X5 for night sky photography.

  2. #2
    Corran's Avatar
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    Re: Wanderlust 4x5 P&S

    Yes, I have, but with the intent being startrails, not traditional wide-field. However, I want a good German equatorial mount some day, and I would do more with that.

    See here:
    http://www.largeformatphotography.in...317-Startrails!

    I haven't done any in a while. Weather has been generally poor and my time short.

    I think the focal lengths for traditional wide field would be longer though. 90mm is fairly wide and will have a lot of foreground unless you are pointed pretty far up.
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  3. #3
    Drew Bedo's Avatar
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    Re: Wanderlust 4x5 P&S

    Any Astro-Photo enthusiasts thinking of putting a TW behind a serious telescope?

    I was thinking of using the TW body with a little spotting scope for thet stacked Telephoto look associated with 35mm .
    Drew Bedo
    www.quietlightphoto.com
    http://www.artsyhome.com/author/drew-bedo




    There are only three types of mounting flanges; too big, too small and wrong thread!

  4. #4

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    Re: Wanderlust 4x5 P&S

    Quote Originally Posted by Corran View Post
    Yes, I have, but with the intent being startrails, not traditional wide-field. However, I want a good German equatorial mount some day, and I would do more with that.

    See here:
    http://www.largeformatphotography.in...317-Startrails!

    I haven't done any in a while. Weather has been generally poor and my time short.

    I think the focal lengths for traditional wide field would be longer though. 90mm is fairly wide and will have a lot of foreground unless you are pointed pretty far up.
    A good German equatorial mount would be very expensive. I was thinking more of a simple 'barndoor' type mount. True, tracking is limited from 10 to 20 min. depending on fl and degree of enlargement but they are simple to construct and cheap. Many years ago I saw a design for a special barndoor mount that had the driven board lifting the mounting board that the camera was attached to. This design, if constructed with care, could tract with amazing accuracy for several hours.

    I was thinking along the lines of using HP5 and trying only for stars of mag 5 or more in a short 2-5 min exposure. I don't think even the brightest extended objects would show up at all.

  5. #5
    That's a camera?
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    Re: Wanderlust 4x5 P&S

    Given that the TW is so light, I am tempted to mount it on my Vixen Polarie (baby EQ mount for light cameras).Click image for larger version. 

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  6. #6
    Corran's Avatar
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    Re: Wanderlust 4x5 P&S

    Quote Originally Posted by plywood View Post
    A good German equatorial mount would be very expensive.
    Oh I know, I kinda want this:
    http://www.amazon.com/Celestron-Comp...dp/B0024OEW3Q/

    Of course, the telescope is extra! But, I recently bought some lens elements that would make a really nice Dobsonian...
    Bryan | Blog | YouTube | Instagram | Portfolio
    All comments and thoughtful critique welcome

  7. #7

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    Re: Astrophotography with the Travelwide 4x5?

    Had to look up that Vixen Polarie. At $380 it seems a bit pricey for what you get. With a 1 rpm Hankscraft motor and a few bits of hardware and some plywood I think I could build something that would work as well for maybe 1/10 that price. It would not be as compact but would still run on batteries and be a completely mobile setup.

  8. #8

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    Re: Astrophotography with the Travelwide 4x5?

    Quote Originally Posted by plywood View Post
    Had to look up that Vixen Polarie. At $380 it seems a bit pricey for what you get. With a 1 rpm Hankscraft motor and a few bits of hardware and some plywood I think I could build something that would work as well for maybe 1/10 that price. It would not be as compact but would still run on batteries and be a completely mobile setup.
    You will fiddling with it for awhile... The earth turns at 1 RPD (day)...

    The "barn door" mount works, but only for a shorter while that might allow a full exposure with a smaller camera with a high f ratio, but with a longer exposure on a large camera, the "barn door" only tilts on one axis, so the stars will smear as it does not follow the circular path...

    Piggybacking the camera on a well set-up equatorial mount using the scope as a guide scope works well...

    Another problem with sheet film astro images is with the camera (aiming up), that when the dark slide is pulled in the damp night air, the moisture can cause the film to flex/bulge until it settles, resulting uneven focus as the focal plane is moving with the film... (35mm or digital don't bounce around like that...)

    Steve K

  9. #9
    That's a camera?
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    Re: Astrophotography with the Travelwide 4x5?

    Quote Originally Posted by plywood View Post
    Had to look up that Vixen Polarie. At $380 it seems a bit pricey for what you get. With a 1 rpm Hankscraft motor and a few bits of hardware and some plywood I think I could build something that would work as well for maybe 1/10 that price. It would not be as compact but would still run on batteries and be a completely mobile setup.
    Yeah. I get it. As an apartment dweller, I don't have the kind of workshop access that some folks do.

  10. #10

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    Re: Astrophotography with the Travelwide 4x5?

    LabRat,
    No, the motor is not for direct drive. It turns a 1/4-20 bolt in a pivoted thread at 11.25 inches from the axis. At least that is the measurement I remember. So that a mark on the edge of a 22.5 inch diameter circle is moving at 1/20 inch per minute. Does that make sense now? Anyway, I was thinking of using a 1/4-20 threaded rod bent to that 11.25 inch radius and have it driven by the 1/4-20 bolt rotating at 1 rpm. That would take care of the tangent error of a straight barndoor mount. You would only need about 12 inches of threaded rod bent around about 1/8 of a 22.5 inch circle, a sector if you will. The motor with bolt can swing away to reset the sector. This idea isn't mine, I saw it in some old Sky & Telescope I think.

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