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  1. #11
    bobwysiwyg's Avatar
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    Perhaps NASA (think deep pockets filled with tax $$) may have used some sort of mount that compensates for the earth's rotation during each exposure??
    WYSIWYG - At least that's my goal.

    Portfolio-http://apug.org/forums/portfolios.php?u=25518

  2. #12

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    A couple of notes on night shooting with film:

    a) I would suggest Provia (gives a blue/purple biased image), Fuji T64 Tunsten, (gives a blue-biased image) or Kodak 64T tungsten (gives a blue/black biased image) as better alternatives than Astia or Velvia films. These films, to my eye, gives more "natural" looking night-color renditions.

    b) The only way to capture stars as points of light would be to use extremely high-ISO settings (as on digi-cams), or... to make a bunch of short single exposures on the same frame of film. This also multiplies the number of "stars" in an image.

    This is most likely how the Death Valley image was created (multiple images on same film or sensor)... note they mention it's comprised of 30-different images.

  3. #13
    Photo Engineer's Avatar
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    Quote Originally Posted by bobwysiwyg View Post
    Perhaps NASA (think deep pockets filled with tax $$) may have used some sort of mount that compensates for the earth's rotation during each exposure??
    Any good telescope comes with such a mount! They are rather inexpensive and very good quality. The telescope and mount can be purchased for under $1500 US in most cases. I have not looked recently, but you might try Celestron for some examples.

    People often get a distorted view of what is going on with tax $$. Sorry, on this one it is an el-cheapo.

    OTOH, shuttle toilet seats cost a fortune. And, don't get hit with one during re-entry (In joke for "dead like me" watchers)

    PE

  4. #14

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    With a telescope motor they must separately shoot the starts, and then separately shoot non-moving landscape with a lens.

  5. #15
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    Yes, you must create a mask that represents the skyline that will move during the shot. Then photograph the stars with a moving mount to prevent circular patterns.

    PE

  6. #16
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    If you are using long shutter speeds, not B (brief time)that is mechanical in your camera, make sure you take a spare camera battery.
    Ben

  7. #17

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    "B" stands for Bulb, as in the rubber pneumatic device people squeezed to release the shutter.
    The shutter would stay open for as long as pressure was high, i.e. as long as the bulb was kept squeezed.

    That in contrast to time, a.k.a. "T", in which the shutter is opened and remains open without needing prolonged or further action.

    But yes: find a mechanical camera to do many long exposures, or stock up on batteries.

  8. #18
    Nicholas Lindan's Avatar
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    If you are looking for something like the NASA/Death Valley shot:

    o Track the stars - this means the stars stay still and the horizon goes all streaky

    o Take another picture without tracking: stable horizon, streaky stars

    o Combine the two

    An older technique is to use a mat-box of a faux-horizon that rotates with the camera as it
    tracks the stars.

    You can get more info on the astro fora. For good milky-way images you will need a special
    filter that lets through the hydrogen lines and blocks everything else. The best film to use
    is hyper sensitized Technical Pan because it has extended red sensitivity where the hydrogen
    doth glow. High speed Ektachrome is also well thought of for astro pictures, as is using Tech
    Pan with separation filters. Note on separation filters: the colors used for the filters quite often
    aren't red, blue and green and often the image isn't limited to just 3 filtered images. The output
    from each of the filters is colored and combined for 'aesthetic' effect, not semblance to any
    reality perceived by human eye. The technique is used by NASA to generate Hubble eye candy.
    DARKROOM AUTOMATION
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  9. #19
    Nicholas Lindan's Avatar
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    It is possible, and also probable, the NASA/DV image was done with the simple expedient of using a $100,000 supercooled sensor that was otherwise surplus to requirements (why buy 1 for $100,000 when you can get ten for only $1,500,000 - your tax dollars at work). This being APUG the ground rules, and most budgets, forbid such a solution.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  10. #20

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    I do some astrophotograhy on a pretty regular basis.

    The biggest factor you'll need to consider is the local light pollution. That alone will determine the limit of your exposure time. If the desert is truly dark (many miles from any cities) consider yourself very lucky!

    My experience has been that lenses (especially wide angle lenses) record stars much better when stopped down one or two stops.

    Fast film isn't necessarily the best choice. The key factors in astrophotography are the red sensitivity and the reciprocity characteristics. A current film that's excellent for stars is Kodak E200 color transparency film. I really like this film for stars in my medium format camera. I've also had moderate success with Kodak Tmax 100 film.

    If you want star trails, all you need to do is mount your camera on your tripod and lock the shutter open. Exposures can be from 30 seconds to several hours if need be. Again, the amount of local light pollution will determine how long you can leave the shutter open. Bracket your shots if time allows.

    The amount the stars will trail will depend on the portion of the sky you have the camera pointed at, the focal length of the lens, and the exposure time. Wide angles generally won't trail much unless exposures are considerably long. A long telephoto could do it in as little as a minute.

    If you don't want star trails, your camera will need to track the night sky. For this a simple telescope with a electronic tracking mount will do. It doesn't have to be expensive with "GOTO" or GPS functions. I use a style called a german equatorial mount. This style is easily adaptable and I use it for 35mm, medium format and 4x5 large format cameras; for my purposes it works very well solely as a camera platform.

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