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  1. #31
    Sirius Glass's Avatar
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    Quote Originally Posted by Ian Grant View Post
    The Fresnel screen is plastic :o

    Ian
    But what I said still holds!

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  2. #32
    Ian Grant's Avatar
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    Since the original posts I've started making/grinding my own GG screens , I made at least a dozen during May - Quarter plate upward to 10x8 and then also re-cut some commercial screens I'd bought previously.

    Yesterday I put one of my own screens in the Crown Graphic with the fresnel and it was a real eye-opener yet another leap in brightness. The old screens were an original Graflex and new a couple of years go from the leading US supplier, both much the same.

    Now for the first time in 3 or 4 years since I bought the Crown Graphic it's really easy to focus even in relatively low light, and also with a 90mm or 75mm lens, I guess I have Dave Parker (satin Snow) to thank I watched & listened and unfairly didn't believe, but now making screens I do.

    Ian

  3. #33
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    Quote Originally Posted by Ian Grant View Post
    Since the original posts I've started making/grinding my own GG screens , I made at least a dozen during May - Quarter plate upward to 10x8 and then also re-cut some commercial screens I'd bought previously.

    Yesterday I put one of my own screens in the Crown Graphic with the fresnel and it was a real eye-opener yet another leap in brightness. The old screens were an original Graflex and new a couple of years go from the leading US supplier, both much the same.

    Now for the first time in 3 or 4 years since I bought the Crown Graphic it's really easy to focus even in relatively low light, and also with a 90mm or 75mm lens, I guess I have Dave Parker (satin Snow) to thank I watched & listened and unfairly didn't believe, but now making screens I do.

    Ian
    Will you sell me a GG for my Crown Grapic?

  4. #34

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    Quote Originally Posted by kompressor View Post
    Will you sell me a GG for my Crown Grapic?
    Or perhaps write an Article on how you do it? I've seen other descriptions elsewhere and it seems fairly straight forward, but few of them claim your degree of improvement over an OEM screen...

  5. #35
    Ian Grant's Avatar
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    David, I started writing something a couple of days ago, I will post it on APUG in a day or so.

    It really is extremely straight forward and easy, I began out of pure necessity because I had a number of cameras and backs with no screens, a 10x8 camera that arrived with the original screen shattered etc. Buying commercial screens would have cost me over $350, a lot less when Dave Parker (Satin Snow) and Geert, (GVB), were still making screen but now there's no competition. Instead I made all my screens, 10 assorted sizes for less than £15 ($20) and I have enough Silicon Carbide grit to cut at least20 time that number

    You can choose the degree of fineness when you grind each screen, I made 3 or 4 variations first for my Speed/Crown Graphics, then tried them out before deciding on my grinding regime finally regrinding all to match.

    It's also worth giving old screens a re-grind and the screens in my pre-WWII 9x12 cameras are now greatly improved.

    Ian

  6. #36
    Ian Grant's Avatar
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    Ground Glass. --Rev. Arthur East

    Quote Originally Posted by David Grenet View Post
    Or perhaps write an Article on how you do it? I've seen other descriptions elsewhere and it seems fairly straight forward, but few of them claim your degree of improvement over an OEM screen...

    From The British Journal Photographic Almanac 1898


    Ground Glass. --Rev. Arthur East says that there often appear in photo-graphic papers articles on substitutes for ground glass, it being little understood, probably, what an exceedingly easy process it is to make the very thing itself; and that starch, arrow-root, and suchlike things are almost, if not, quite as much trouble to utilise (and of not one-tenth the beauty and durability) as ground glass at home.

    The following plan may, therefore, be acceptable :—

    Take a clean negative glass of any size, and lay it on a flat, hard surface, such as a board or stone slab and sprinkle on this a pinch of emery powder, No. 1 (flour of emery will do, and do well, but the next quality, coarser, works more ‘ quickly). Lay on this a piece of broken glass about an inch square or there-abuts, and moisten the emery with a little water (do not use much so as to let it get 'sloppy,' and work all about).

    Now work round and round all over the negative glass with the moderate pressure of two or three fingers until the gritty sound begins to go, which means that your emery is getting ground too line (this will be in about a minute or two). Put on another pinch of emery, and work as before; in about ten minutes rinse your plate under the tap, and you will find probably with your finely ground surface a few ‘islands’ looking shiny, return the plate to the board, and work these patches out, and you will find a surface ground as finely as any you can buy, and there is no difficulty whatever in getting a perfectly even surface free from any scratches or defect whatever.

    Any ironmonger will supply the emery, a pennyworth by post if you live ‘beyond the region of lamp-posts,’ and even the ordinary domestic knife powder will do, but it is too fine and works too slowly, and is inclined to be gritty and make deep scores in the surface of the glass.

    If an extra finely ground surface is required as for a focussing glass, it only means rather longer grinding, and perhaps a little flour of emery to finish with; but the whole process can easily be done with one quality of emery, of which the best is probably the No. 1. If the surface of negative glasses were perfectly flat, it would be possible to grind two together, but the surface is never flat, and a small piece of glass is best to grind with. Some samples of glass are harder than others, an take rather longer to finish.

    __________________________________________________ ________

    Substitute #400 grit Silicon Carbide for the coarse emery and #600 grit Silicon Carbide for the "Flour of Emery" finer grade, and everything else is the same

    Ian
    Last edited by Ian Grant; 06-24-2010 at 09:47 AM. Click to view previous post history. Reason: ocr issues

  7. #37
    Ian Grant's Avatar
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    Quote Originally Posted by David Grenet View Post
    Or perhaps write an Article on how you do it? I've seen other descriptions elsewhere and it seems fairly straight forward, but few of them claim your degree of improvement over an OEM screen...
    Done

    Ian

  8. #38
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    I read the article and was surprised at how easy it is. I found a supplier of grit that sells 400 & 600 for $4.50/pound. Time to brighten up the screens on my 4x5's!

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