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  1. #1
    Ian Grant's Avatar
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    What a huge difference the Glass makes

    Recently I restored a couple of Speed/Crown Graphics, I'd intended to buy new glass but didn't get a chance on my last visit to the UK. I also need new glass for a 10"x8" and 9x12cm camera.

    I have 2 5x4's sat side by side on tripods and was astonished at the differences in screen brightness, I expected a stop or so but instead its well over 3½ stops, and that's with a handicap the camera with the brighter screen had a slower lens.

    The Wista 54DX with the standard Wista screen & fresnel had a 150mm 5.6 Sironar at full aperture and the Crown Graphic a 150mm f4.5 Tessar (coated), and a new ground glass bought via Ebay (2½ years ago), both focussed at infinity.

    Using my Spotmeter & reading from an area of clear blue sky on the screen the Wista gave a reading of 14, while the Graphic was 11.4. I then stopped the Sironar down until both screens had the same approx apparent brightness, that was between 16/22, checking the Tessar on the Wista I had a comparable reading of 14.7 as I'd expect with a faster lens.

    So in fact the difference in screen brightness is equivalent to 4 f-stops, which is highly significant. The dilemma is what glass to use that will get reasonably close to the brightness of the Wista screen on the other cameras.

    The screen on the Crown Graphic came from a reputable US supplier of ground glass screens, it is slightly brighter than the original screen. (Not Satinsnow).

    There seem to be are a number of options:
    1. Beattie or Maxwell screen
    2. Adapt a Wista or Cambo screen & fresnel (to fit).
    3. GVB & Lumigrid
    4. GVB Standard

    The first option is ruled out as too expensive I need up to 5 screens, the 2nd may be the best for one or two cameras but there may be an issue with film plane register adding the fresnel. The 3rd option seems the best for the other screen, maybe with plain GVB glass on the 9x12's.

    Comments on the Shen Hao Glass/Fresnel would be appreciated that option is quite reasonably priced, also sources for reasonably priced fresnels.

    Ian

  2. #2
    jeroldharter's Avatar
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    5 screens is a lot so I understand your reluctance for the Maxwell. I researched this awhile back and decided to get a Maxwell screen for my 4x5 although there is not a huge amount of info out there. I can tell you that is is great and makes a huge difference, especially on the wide angle lenses. So if you have a wide angle setup with a bag bellows or something like that, consider splurging on the Maxwell for that camera. Likewise, if you have a particular setup for low-light photography.
    Jerold Harter MD

  3. #3
    Ian Grant's Avatar
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    Jerold, I actually have a Beattie screen on a 10x8 so yes I appreciate the difference, but the screens on my Wista & Cambo 5x4's are excellent and I'm happy with that quality.

    My problem is a Beattie or Maxwell screen costs more than the Crown Graphics worth

    Ian

  4. #4

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    But what value do you put on your crowngraphic Ian?

    I will spend more on a camera than it is worth to improve my picture takeing pleasure if I can afford it and think it desireable enough, its worth and value are not the same thing in my book. It is a personal thing I do it for me, if someone else benifits after I have finished with it so be it, I regard it as part of the cost of my hobby. But then my youngest camera is over 30 and I drive a 10 year old car so what do I know.

    Regards Paul.

  5. #5
    Ian Grant's Avatar
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    Quote Originally Posted by Paul. View Post
    But what value do you put on your crown graphic Ian? . . . . . . .
    Regards Paul.
    My Crown Graphic isn't my main 5x4 camera, it's not so much the monetary value as its practical value as a hand-held LF camera. It just doesn't warrant buying a new Beattie/Maxwell screen when I'd be more than happy with a screen that was close in brightness to my Wista and Cambo's screens.

    Yes of course you're right to say it's worth improving a camera if possible, and I've changed the lens and now feel it's worth upgrading the screen, purely to make it a more usable camera but at a reasonable cost.

    Ian

  6. #6
    ic-racer's Avatar
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    I'm curious as to what the results would be without the fresnel on the Wista. Or if the fresnel were on the Graphic.

  7. #7

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    Quote Originally Posted by ic-racer View Post
    I'm curious as to what the results would be without the fresnel on the Wista. Or if the fresnel were on the Graphic.
    That was my thought too. The fresnel would skew the results significantly so its like comparing apples and oranges except that it shows that a frenel makes things brighter if viewed from the correct angle.

    But brightness does not necessarily equate to ease of focussing. It equates to ease seeing what you are looking at but a screen of sufficient coarsness will snap into focus whereas some of the bright screens are difficult to find the focus point. There is balance between the two which is optimum.

    A while back I removed the boss screen from my camera and put the original linhof screen back on. I was amazed at how much easier it was to focus even though it was not as bright as the boss screen.

  8. #8
    Ian Grant's Avatar
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    As you both asked I thought I'd check. However the Wista doesn't have a separate Screen and fresnel, it's an all in one Super screen plus a protective cover with a grid.

    The Wista screen is very bright and easy to focus, in comparison the screen on the Crown Graphic never produces a particularly sharp crisp visual image.

    Ian

  9. #9

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    All in one or not the wistas seem to have a fresnel screen.
    Was the spot you metered in the centre of the screen?
    If not, I would test again using the dead centre of the screen with everything centred at zero on the camera and place the spot meter right on the screen centre so that it is looking from a perfectly perpendicular angle to the centre of the screen. That should give a better indication of relative brightness regardless of fresnel. 4 stops is a huge difference.

  10. #10
    Ian Grant's Avatar
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    The Wista screen has the Fresnel built into it.

    It makes virtuall no difference wheter you read from the dead centre of the screen or not, I just tried it, the Wista does have a non fresnel centre circle of just under an inch diameter, and of course if you view from off centre this area is more directional.

    None of that alters the fact that theres a very definite 4 stops difference between the two screens.

    Ian

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