8 Comments

  1. Jonathan
    11/11/2010
    Reply

    Yes, I used mirror lock-up and a cable release. I left it at least 10 seconds after locking the mirror up before I exposed the picture.

    I experimented with longer exposures but I was also nervous about any tiny vibrations at that focal length.

    The problem seems to be the lack of focus and sharpness on the lens itself. I’ve managed photos of a similar standard to yours with my 70-300mm lens.

  2. […] writing a scathing review of my 500mm mirror lens the other day, I decided to have another go with mine. I got much better-exposed results this time, […]

  3. ChrisJ
    3/29/2012
    Reply

    There is one type of mirror lens that works well, a Newtonian Telescope, a Skywatcher 130 is (relatively) cheap to buy and comes with a really heavy duty tripod, which is another essential, and gives you a 650mm f4 lens when used as a prime. On the lens cover there is a cap covering a hole, fit the lens cover and remove the cap and you have an f8 lens with all the advantages of stopping down brings in contrast and sharpness.

    You can, of course, fit an eyepiece and use that to project it’s image onto your sensor, then you have more than enough magnification for the Planets, Nebulae etc.

    I find that 1/125th of a second at f8 and 100 ISO is almost always the correct exposure for the Moon, even a crescent Moon, just because part of the Moon is covered in shadow the part you want to expose for is exactly the same exposure as the full Moon, the shadow doesn’t make the exposed area any less bright, which is kinda counter intuitive until you think about it.

    Chris

    • 3/29/2012
      Reply

      Since I wrote this article, I actually purchased a Cassegrain-Maksutov mirror telescope, rather than a Newtonian. The quality is excellent, so perhaps I should be more specific in my conclusion of this article: not all mirror lenses are bad, but the cheap, generic mirror lenses for cameras probably are!

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