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Thread: Fresnel lenses and ground glass focusing screens your worries answered

  1. #61
    Serious Amateur Photographer pepeguitarra's Avatar
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    Re: Fresnel lenses and ground glass focusing screens your worries answered

    Thanks Doremus. It makes sense, since the box had a label that said: Superscreen/grounglass/fresnel. I am going to replace it and will post results here.

  2. #62
    Serious Amateur Photographer pepeguitarra's Avatar
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    Re: Fresnel lenses and ground glass focusing screens your worries answered

    Quote Originally Posted by Bob Salomon View Post
    Your gg just has to be positioned by a technician.
    Thank you Bob. That is why I love the knowledge in this LF DIY section. I just put the fresnel back the way it came from factory and it is fine.

  3. #63
    Serious Amateur Photographer pepeguitarra's Avatar
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    Re: Fresnel lenses and ground glass focusing screens your worries answered

    Quote Originally Posted by Doremus Scudder View Post
    The Wista Fresnel/ground glass is more than just a Fresnel lens. Every Wista Fresnel screen I know of is a sandwich of ground glass (acrylic, actually), frosted on one side with a Fresnel lens affixed to the viewing side. It is meant to replace the ground glass, not be added to an existing one. If your Calumet came with just a plain ground glass, and the Wista screen is the right size, you should just remove the original one and replace it with the Wista screen, frosted side facing the lens. Then you should be able to focus without a problem.

    Best,

    Doremus
    Doremus: I replaced the gg on the CC400 with the WISTA Superscreen and it is unbelievable, it looks like the Maxwell screen I put on my Rollei 2.8F. I took a shot and developed it, and it is just sharp and in focus. Thank you very much for your DIY advice.

  4. #64

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    Re: Fresnel lenses and ground glass focusing screens your worries answered

    Quote Originally Posted by pepeguitarra View Post
    Doremus: I replaced the gg on the CC400 with the WISTA Superscreen and it is unbelievable, it looks like the Maxwell screen I put on my Rollei 2.8F. I took a shot and developed it, and it is just sharp and in focus. Thank you very much for your DIY advice.
    Glad to have been of assistance!

  5. #65

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    Re: Fresnel lenses and ground glass focusing screens your worries answered

    Quote Originally Posted by pepeguitarra View Post
    Doremus: I replaced the gg on the CC400 with the WISTA Superscreen and it is unbelievable, it looks like the Maxwell screen I put on my Rollei 2.8F. I took a shot and developed it, and it is just sharp and in focus. Thank you very much for your DIY advice.
    Just don’t do what Mary Ellen Mark did with her Rollei 6008 cameras. She spent a day cleaning them and then put the focusing screens back in upside down! She sent her cameras to the factory to solve the problem!

  6. #66

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    Re: Fresnel lenses and ground glass focusing screens your worries answered

    Its always a good idea, when utilizing an acrylic fresnel/ground combo screen (single unit with fresnel field towards rear), to place a protective cover glass (either plain or lined as per choice) behind this. Fresnel surfaces are rather delicate. Furthermore, they will tend to flex, if unprotected, with contact pressure associated with the (careless?) use of a loupe - to the point of visible de-focus. The only potential downside to this glass/acrylic "sandwich" is that it can trap moisture and require occasional disassembly to allow for effective drying.

  7. #67
    Serious Amateur Photographer pepeguitarra's Avatar
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    Re: Fresnel lenses and ground glass focusing screens your worries answered

    Quote Originally Posted by John Layton View Post
    Its always a good idea, when utilizing an acrylic fresnel/ground combo screen (single unit with fresnel field towards rear), to place a protective cover glass (either plain or lined as per choice) behind this. Fresnel surfaces are rather delicate. Furthermore, they will tend to flex, if unprotected, with contact pressure associated with the (careless?) use of a loupe - to the point of visible de-focus. The only potential downside to this glass/acrylic "sandwich" is that it can trap moisture and require occasional disassembly to allow for effective drying.
    Thank you John, that makes absolutely sense. I will cover it. Regarding a loupe, I do not use one. I recently had cataracts surgery and have bionic eyes, I can focus clearly without loupe, and even without dark cloth.

  8. #68

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    Re: Fresnel lenses and ground glass focusing screens your worries answered

    Quote Originally Posted by John Layton View Post
    Its always a good idea, when utilizing an acrylic Fresnel/ground combo screen (single unit with Fresnel field towards rear), to place a protective cover glass (either plain or lined as per choice) behind this. Fresnel surfaces are rather delicate. Furthermore, they will tend to flex, if unprotected, with contact pressure associated with the (careless?) use of a loupe - to the point of visible de-focus. The only potential downside to this glass/acrylic "sandwich" is that it can trap moisture and require occasional disassembly to allow for effective drying.
    I second this! The Wista cameras all have a protective glass over the Fresnel screen.

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