Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,493   Posts: 1,542,983   Online: 843
      
Page 2 of 2 FirstFirst 12
Results 11 to 15 of 15
  1. #11
    Diapositivo's Avatar
    Join Date
    Nov 2009
    Location
    Rome, Italy
    Shooter
    35mm
    Posts
    1,844
    Quote Originally Posted by Markster View Post
    I wonder how such a lense would do with astronomy shots... Anybody tried it, or know?
    As far as know many telescopes are based on mirrors (Newton, Cassegrain, that stuff) and catadioptric lenses in photography are basically based on the same concepts.
    In astrophotography everything is in focus so one should never get rings.

    When I'm rich I'll certainly buy a Minolta RF 250/5.6 such a nice portable addition to my walk-around bag.
    At the moment they are a bit too expensive:

    http://www.ebay.it/itm/Minolta-RF-5-...item4850e73dbe (this probably is exaggerately expensive).

    For most subjects (those without shining out-of-focus points) the circular effect is noticeable but not really disturbing.
    Fabrizio Ruggeri fine art photography site: http://fabrizio-ruggeri.artistwebsites.com
    Stock images at Imagebroker: http://www.imagebroker.com/#/search/ib_fbr

  2. #12
    Barry S's Avatar
    Join Date
    Jan 2007
    Location
    DC Metro
    Shooter
    Large Format
    Posts
    1,252
    Images
    31
    Quote Originally Posted by Markster View Post
    I wonder how such a lense would do with astronomy shots... Anybody tried it, or know?
    If you're experiencing bokeh issues in the midst of astrophotography--I suggest you dive for cover! Seriously, these are a similar design to mirror telescopes and there are no issues with photographing the moon. I don't think a 500mm lens will be of much use with other astronomical objects.

  3. #13
    hgernhardt's Avatar
    Join Date
    Dec 2012
    Location
    Brockton, MA
    Shooter
    Medium Format
    Posts
    68
    Quote Originally Posted by Markster View Post
    I wonder how such a lense would do with astronomy shots... Anybody tried it, or know?
    They work absolutely amazingly. Especially when your mirror lens is an 8-inch Celestron with a mirrored Mylar solar filter over the aperture. My father took some astounding sunspot images in his time with that ol' Celestron.

    Of course, the closest I personally got to astrophotography was taking images of the Orion constellation, and a couple of the moon—all with standard camera lenses.
    Henry C. Gernhardt, III

  4. #14
    Markster's Avatar
    Join Date
    Dec 2010
    Location
    Denver area
    Shooter
    35mm
    Posts
    307
    I was thinking more specifically of the 500mm, rather than attaching the camera directly to a telescope.

    I imagine it would work well with the moon (as mentioned).

    As far as cheap (or, cheapER) conventional solutions, if you put a 1.4x or 2x converter on it and you can bring that up to 1000mm. Further, I don't think there's anything stopping you from using 2 convertors on the 500mm.

    The problem then becomes light sensitivity and shutter speeds required, I suppose.

    It does pique the imagination, does it not?
    -Markster

    Canon AE-1P 35mm | 50mm/f1.8 FDn | 28mm/2.8 FD | 70-200mm/f4-5 FD | 35-70mm/F2.8-3.5 Sigma FD

  5. #15
    lxdude's Avatar
    Join Date
    Apr 2009
    Location
    Redlands, So. Calif.
    Shooter
    Multi Format
    Posts
    6,646
    I have the Tamron SP 500mm f/8 mirror lens (55B), and I thoroughly enjoy it. Inexpensive these days, it was always reasonably priced. Sharp and with very good contrast for a mirror. I have the Tamron SP 2X teleconverter, (01F) a good performer, which makes it a 1000mm f/16. I bought it mainly for long shots of distant objects, most at infinity, and birds and aircraft against the sky- bokeh issues are nonexistent for those. The whole setup with cases, filters, everything, cost me about $120.

    As polyglot says, avoiding specular highlights, or any distinct highlights, will minimize the donut bokeh. Having the background in shadow, or shooting against a very uniform background will minimize it, too. I have found that a very busy background, like dense grasses, will also work, because the doubling of lines is not so noticeable, and if the background is really busy, the doubling actually has the effect of blending, reducing the effect.
    One thing I like about the Tamron is the very close focusing ability. It goes to 1:3, and 1:1.5 with the 2X converter. I can get nice shots close up in which the depth of field is so shallow that the background just blurs into a smooth mass. I have been able to take flower shots in which objects which were out of focus did not display objectionable bokeh.

    A mirror can be a lot of fun. Avoiding the donuts means choosing shots carefully, and simply avoiding certain types of shots, but to me that's part of the fun. There is no way I would be carrying a regular 500mm, so the trade-offs mean getting shots with a mirror and dealing with its characteristics, or not getting the shots at all.
    Last edited by lxdude; 03-01-2013 at 11:38 PM. Click to view previous post history. Reason: typo
    I do use a digital device in my photographic pursuits when necessary.
    When someone rags on me for using film, I use a middle digit, upraised.

Page 2 of 2 FirstFirst 12


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin