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  1. #21
    Nightfly's Avatar
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    Quote Originally Posted by 2F/2F View Post
    What are the chances of getting a nice wide-field shot without having the camera piggybacked on an automatic telescope? Would a 400 film pushed a lot in development do it? Say for example that I was using a 2.8 lens. I'm thinking something like T-Max or Neopan 400.
    A very fast normal or wide angle lens, at least f/2 and fast film will give you a shot at what you describe. Use Provia 400X pushed 1 stop, maybe two. Try a fast b&w film like T-Max. Remember to go to the darkest skies you can find. The Summer Milky Way is due south once its dark. Try 45-90 second exposures at f/2. 60-120 seconds f/2.8. Stars will trail after just 20 seconds or so, but you will get the idea of how it all works.

    Good luck.
    Last edited by Nightfly; 08-10-2009 at 06:29 AM. Click to view previous post history.

  2. #22
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    HP5+ is reported to have slightly less reciprocity failure and much better response to red emission nebulae than TMY-1. Haven't seen reports on TMY-2 for this purpose, or on Neopan 400.

    Both the Kodak and Ilford chromogenic B&W films get good ratings for astrophotography.

    Lee

  3. #23
    Lee L's Avatar
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    The attached .pdf has some realistic exposure times for unguided astrophotos short enough not to show star trails in 35mm format. Declination is equivalent to earth's latitude projected out into space, so 0-30 declination is everything that would be in a band with +/- 30 degrees north or south of an east-west line directly through the zenith if you're standing on the equator. 90 degrees of declination defines the N and S celestial poles (Polaris and the Southern Cross). Declination is usually shown on star maps, and there are many online that you can use. www.google.com/sky shows two numbers in the lower left of the screen. The second number is declination in degrees, minutes, seconds. You can search there for the constellation you're shooting and find the declination with the cursor.

    As you can see from the attached table, from page 25, Wide-Field Astrophotography, Robert Reeves, as you shoot nearer the celestial equator (0-30 declination) things appear to cover a greater angle more quickly, and so shorter exposures are needed to avoid blur. As you point you camera closer to the north or south celestial poles, the rate of angular motion of the stars is less, and you can make longer exposures without blurring. Shorter focal length lenses can also be open longer than longer focal lengths without apparent star motion blur.

    Lee
    Attached Files

  4. #24
    2F/2F's Avatar
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    Quote Originally Posted by Lee L View Post
    The attached .pdf has some realistic exposure times for unguided astrophotos short enough not to show star trails in 35mm format. Declination is equivalent to earth's latitude projected out into space, so 0-30 declination is everything that would be in a band with +/- 30 degrees north or south of an east-west line directly through the zenith if you're standing on the equator. 90 degrees of declination defines the N and S celestial poles (Polaris and the Southern Cross). Declination is usually shown on star maps, and there are many online that you can use. www.google.com/sky shows two numbers in the lower left of the screen. The second number is declination in degrees, minutes, seconds. You can search there for the constellation you're shooting and find the declination with the cursor.

    As you can see from the attached table, from page 25, Wide-Field Astrophotography, Robert Reeves, as you shoot nearer the celestial equator (0-30 declination) things appear to cover a greater angle more quickly, and so shorter exposures are needed to avoid blur. As you point you camera closer to the north or south celestial poles, the rate of angular motion of the stars is less, and you can make longer exposures without blurring. Shorter focal length lenses can also be open longer than longer focal lengths without apparent star motion blur.

    Lee
    Thanks, Lee.

    I assume that at a given print size, a print from medium format will show less discernible trailing on the print than the same print from 35mm. Is this correct?
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  5. #25
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    Quote Originally Posted by 2F/2F View Post
    Thanks, Lee.

    I assume that at a given print size, a print from medium format will show less discernible trailing on the print than the same print from 35mm. Is this correct?
    That's a reasonable assumption to make. You could throw in a magnification factor to relate whatever MF format you're using to 35mm and try that, then modify as needed given your results.

    Akira Fuji (http://www.davidmalin.com/fujii/fujii_index.html) is one of the best known MF astrophotographers. I believe he sometimes uses a Zeiss Softar type filter to make the brighter stars appear larger, more like they do to the naked eye. MF and a good lens can make the main stars in a constellation seem to get lost in the "background" stars.

    Lee

  6. #26
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    As a follow up to this thread, I just scanned the 120 roll of Ektar I had tested in June.

    Ektar 100'S performance for daytime landscapes has blown me away. I am able to produce better results than what I was achieving with chrome films. The grain is superior, especially for medium format users. Large scans are grainless.

    For astrophotography the film is certainly usable. It has o.k red response and records stars well. It has a cyan cast, but this can be managed in Photoshop.

    Here is the one test shot from early June. Please excuse the tree in the lower left, I wasn't going to wait for Cygnus to rise higher for just a test, but now I wish I had. When exposed and handled properly in post processing, the film can perform well.

    Pentax 67 with 105mm f/2.4 @ f/3.4
    Kodak Ektar 100 processed normally
    30 minute exposure


    Film? What's that? It's like digital, only better

    Flickr - Nightfly Photography
    Nightfly Astrophotography

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