replacemnt ground glass

Discussion in 'Large Format Cameras and Accessories' started by pellicle, Jul 1, 2010.

  1. pellicle

    pellicle Member

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    Hi

    there was once a fellow making ground glass replacements under the name of Satin Snow. I understand that these are now unavailable.

    As a 4x5 photographer myself I have been wondering about a replacement ground glass for my 4x5 (which is a Toho) and began looking about.

    I was also talking with a friend of mine who does laser etching and cutting and asked if he could make one up for me as a one off. Since his gear is computer CNC type stuff it would then of course be no more trouble for him to make thousands of them (after he has made one). Which lead me to wonder if there remains a market of interest for this sort of product.

    So, anyone know if there is any market (world wide) for a ground glass maker?
     
  2. Christopher Walrath

    Christopher Walrath Member

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    It would be a niche market at best. Practice making them until your process is perfected and then produce a few dozen and market them. It will be slow at first and probably won't pick up much so don't expect to make a mint for a long time. But you could become a go to guy in a dying art. Make ground glasses, that is.
     
  3. domaz

    domaz Member

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    With the article just posted about making ground glasses by Ian Grant I don't see why anyone would bother to buy one. Looks so easy.
     
  4. pellicle

    pellicle Member

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    Hi

    thanks for pointing that out ... I had not spotted it :smile:

    Personally I would give that a go, but after discussing lens adaptors for putting 35mm lenses on another camera (m4/3) and hearing that people were unable to consider simple honing of the adaptor to fine tune the lens I realise that for many anything more complex than applying sticky tape is a daunting engineering task.

    The concept I was exploring with my friend (he's the entrepreneur, I'm just a photographer) was using laser etching to make the viewing brighter (as done by many SLR makers on their screens starting in the 80's).

    :smile:
     
  5. steven_e007

    steven_e007 Member

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    It is very easy to make a ground glass screen and Ian has recently posted instructions.

    I think there would only be a market if your friend could make a screen that was significantly superior to the sort of thing you can make yourself, such as a a Beattie, Maxwell or Boss Screen. I think these have a fresnel lens either cut into them - or sandwiched alongside. Could he cut such a lens? Looking at some of the sites below, they make different screens for different purposes. Either optimised for standard lenses or wide angle, equipped with various grid line patterns and sometimes additional focussing aids. Some screens seem to be camera specific, too, to ensure the registration and fitting matches the previous screen. These makers offer a ground glass screen service, rather than just one screen.

    Personally, as an amateur who likes renovating cameras anyway I am happy to make my own. There will be photographers who need a screen but don't like the DIY route who might buy a pre-made screen at a cheap price, but as the price goes up - they may get very specific and demanding!

    http://www.stabitech.nl/Bosscreen.htm#WhyABosscreenGroundglass
    http://www.mattclara.com/maxwell/
    http://www.brightscreen.com/aboutus.html
     
  6. Ian Grant

    Ian Grant Subscriber

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    I'm sure there is small market for custom laser cut screens but if you look at how the good ones work there's a lot of design, maths and testing gone into them, and there are different requirements for a standard and wide angel screens with larger formats.

    Bill Maxwell must be laser cutting his screens, and presumably has CNC profiles for a variety of screens..

    I'd also guess that someone is already making them for the manufacturers, much in the same way that Camera Bellows (now custom Bellows) have been quietly churning out bellows for almost all the European and US camera manufacturers for years, many million for Kodak alone.

    Ian
     
  7. edp

    edp Member

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    It's not difficult or expensive to make ground glass, but the few I've bought have all been made by Steve Hopf and I'm very happy with them.

    http://hopfglass.com/
     
  8. Steve Smith

    Steve Smith Subscriber

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    Has he tried this yet? I have a laser cutter/engraver at work and I have tried a few times but with no success. I would be interested in learning about his method.


    Steve.
     
  9. pellicle

    pellicle Member

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    Ian

    that is a very good point, and one which I had known but somehow not connected with the idea of interchangability. I am now going to sus out a wide screen for my Toho as when using the 90mm on it in dim rain forests it drives me spakko getting focus.

    thanks :smile:
     
  10. pellicle

    pellicle Member

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    some quick experiments, but nothing serious. There are some interesting points which we'll need to work though and it may of course prove more challenging than its worth.

    thanks for the thoughts :smile:
     
  11. smieglitz

    smieglitz Subscriber

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    "The Devil is in the details."
     
  12. lxdude

    lxdude Member

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    :D:D
     
  13. Sal Santamaura

    Sal Santamaura Member

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    Maxwell screens are molded acrylic.
     
  14. Ian Grant

    Ian Grant Subscriber

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    Makes sense, but making those moulds must be very expensive, hence the high prices.

    So presumably the moulds are laser cut.

    Ian
     
  15. steven_e007

    steven_e007 Member

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    An interesting aside - but I have heard that at one time some focussing screens were made by etching with hydrofluoric acid.

    I'm not suggesting anyone tries this - it is one of the most 'orrible and dangerous chemicals you could possible handle. (That seen in phantom of the opera where he gets horribly disfigured by acid? I bet that was hydrofluoric!!! ;-)

    Anyway, just wondered if anyone else had ever heard of etching screens this way?

    I have in the past made ground glass screens by both sand blasting and bead blasting. I spotted a small factory that specialised in sand blasting and I just walked in the door and asked if they did 'one off' jobs... they did. Sand is far too coarse, but when I made another visit and explained to the guy what I wanted it for, he suggested bead blasting. Bead blasting is much finer. Still a bit too crunchy for precise work, similar to engine valve lapping compund - but very quick and cheap (he just asked for a couple of quid to be chucked in the 'Tea fund.')
     
  16. John Koehrer

    John Koehrer Subscriber

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    I Believe there is a world wide market for the product but the variety needed is large. Steve Hopf obviously figured this out & every screen is basically a one-off.
    Steve says all of his products are hand ground with ~3 day turnaround. Does your friend even want to try and deal with that?
    It sounds like the auction place with fixed sizes and buy it now would be more practical for that kind of production/sales.
    I can see a lot of complaints from the clipped/unclipped & what size actually means to the buyers though. It may be workable to make oversize ground blanks & cut them smaller on demand. something like 9X11 for stock & then anything smaller could be made & edges polished & corners clipped.
     
  17. pellicle

    pellicle Member

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    Hi

    hydrofluric acid goes well well beyond that. The burns are quite minor compared to other acids, but at even modest dilutions it penetrates the skin and lodges in the calcium deposits. Yes your bones. regular exposure (say through work) will cause destruction of the bones with associated loss of the region. Meaning fingers and arms or feet and legs will be at risk.

    If you handle this as part of your work (it was a common element in mag wheel cleaners) I encourage you to take proper precautions with the correct graded safety gloves (and boots if needed) at all times.

    http://en.wikipedia.org/wiki/Hydrofluoric_acid#Safety
     
    Last edited by a moderator: Jul 2, 2010
  18. david_mizen

    david_mizen Member

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    contact with hydrofluric acid even in small quantities can be fatal we had a fatality here a while ago that resulted in the banning of the use of the acid, the victim dissolved from the inside out. he was an experienced lab assistant in the gold industry but when things go wrong they really go wrong there was no antidote on hand insufficient safety equipment .... it resulted in a complete overhaul of the of the use of the stuff

    is it worth the risk??
     
  19. steven_e007

    steven_e007 Member

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    No, of course it isn't. That is why I said in my original post:

    I was merely interested, from a historical point of view, whether anyone has heard of screens being etched this way years ago?
     
  20. Ian Grant

    Ian Grant Subscriber

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    There's still acid etched glass around. People have & still do make screens that way, not so many these dats though.

    Hydrofluoric acid is still used in the jewellery trade.

    Ian