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Thread: Meniscus coverage taken out of barrel

  1. #1
    renes
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    Meniscus coverage taken out of barrel

    Just short qustion: does the coverage of meniscus lens increases when it is used taken out of the barrel? I have heard something like that today. Normaly the coverage reduces when the aperture is opening and increases when it's closing.

  2. #2

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    Re: Meniscus coverage taken out of barrel

    Yes, the coverage increases when out of the barrel. This is because the barrel causes some vignetting.

  3. #3
    renes
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    Re: Meniscus coverage taken out of barrel

    Thanks Stephane.
    Have you noticed is it significant coverage increase or minor?

  4. #4

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    Re: Meniscus coverage taken out of barrel

    Significant. I felt there was no coverage limit

    I can check later how much (in day light). I'll try from the shortest FL I have (140mm?) on 8x10 focused at infinity and tell you tomorrow evening.

    You can also try on your side with whatever you have, so we can compare the results...

  5. #5
    Mark Sawyer's Avatar
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    Re: Meniscus coverage taken out of barrel

    Keep in mind that as you progress outwards farther from the center, the image will degrade significantly. Illumination does not mean useful coverage. But the loss of image quality may be acceptable, even desireable, for those who know how to use such things.
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  6. #6
    LF/ULF Carbon Printer Jim Fitzgerald's Avatar
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    Re: Meniscus coverage taken out of barrel

    So, I'm going to ask the dumb question that I hope someone else out there is curious about. What exactly do you mean when you say " taken out of the barrel" Does this mean you have one piece of glass and you glue it to a lens board. I know I'm not the brightest guy around but this is confusing to me.

  7. #7

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    Re: Meniscus coverage taken out of barrel

    Some of us have iris clamps, so you just unscrew the rear element and fix it on the iris clamp. No glue. No tape.

  8. #8
    LF/ULF Carbon Printer Jim Fitzgerald's Avatar
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    Re: Meniscus coverage taken out of barrel

    Quote Originally Posted by Stephane View Post
    Some of us have iris clamps, so you just unscrew the rear element and fix it on the iris clamp. No glue. No tape.
    Okay, thank you! Now it makes sense. With all of this out of the barrel, uncorked, etc,etc all it is is just like when Mark took the .99 cent magnifying glass and glued it to the lens board. Now I've got it.

  9. #9

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    Re: Meniscus coverage taken out of barrel

    the 150mm covers 8x10, or at least illuminates the gg.

  10. #10
    renes
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    Re: Meniscus coverage taken out of barrel

    Quote Originally Posted by Stephane View Post
    the 150mm covers 8x10, or at least illuminates the gg.
    Thanks. That's significant

    I am fitting two Lancaster meniscus (WA 4" and 6") to the shutters and will check how much the coverage will differ comparing to the barrel mounting.

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