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Thread: mounting gelatine filters between glass

  1. #11

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    Re: mounting gelatine filters between glass

    Quote Originally Posted by Havoc View Post
    I need new filters for my tricolor cameras. I have now found a place that can sell me the right gelatine filters. Only problem is that they cannot mount them between glass. I took apart one of the defective filters and can get the old gelatine out. Still need to see if I can clean it well enough.

    The lady I had at the phone told me that they mount it between 2 plates with spacers in order to avoid Newton rings. Only thing is that I don't have spacers in the original filters. Also the glass is much thinner than what they use (they use 2mm while the originals are 1.4mm). So the plan now is to re-use the old glass.

    But how do you mount those gelatine filters between 2 glass plates? The old ones were glued over the complete surface. I really have no idea what glue to use and even less of a clue how to do this without bubbles. Does anyone has an old book that describes how to do this?

    can you use paper as spacers?

  2. #12

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    Oregon now (formerly Austria)
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    Re: mounting gelatine filters between glass

    Sounds to me like a quick tutorial and some practice with cementing glass, filter, lens elements together is in order. Get some scrap glass and filters and some lens cement and "go to school" and figure out the technique. Some here will likely be able to help. Once you have the technique down, you've solved the problem for life.

    Doremus

  3. #13

    Join Date
    Nov 2017
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    366

    Re: mounting gelatine filters between glass

    Quote Originally Posted by Doremus Scudder View Post
    Sounds to me like a quick tutorial and some practice with cementing glass, filter, lens elements together is in order. Get some scrap glass and filters and some lens cement and "go to school" and figure out the technique. Some here will likely be able to help. Once you have the technique down, you've solved the problem for life.

    Doremus
    Well, I do have some old slide MF glass around, they are sending me a sample of the gelatine filters. So I guess that ordering some canada balsem and reading that nasa article a few times is in order.

    One project turns into 5 others....
    Expert in non-working solutions.

  4. #14
    Drew Wiley
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    Sep 2008
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    Re: mounting gelatine filters between glass

    Polyester filter are optically quite poor. With true Wratten gel filters you have to be careful about how old they are and how they've been stored. They can fade.

  5. #15

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    May 2015
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    SooooCal/LA USA
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    Re: mounting gelatine filters between glass

    You might try looking up C Kenneth Mees (?) and the Wratten & Wainwright company... They invented gelatine filters (later sold to EKC, where Mees became chief scientist)... I have seen old photo tech books that described the process of cementing gels between cover glasses... (I don't have access to my library now...)

    Another tip would be to call the engineering dept at one of the filter manufacturers... They take calls about custom designs and might help... in the US, I would call Tiffen...

    In the (not very) old days in Hollywood was Harrison & Harrison would allow walk-ins for one on one consulting of filter problems...

    Just don't use a process that uses moisture, as it damages the coating...

    Steve K

  6. #16

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    Re: mounting gelatine filters between glass

    Quote Originally Posted by Drew Wiley View Post
    Polyester filter are optically quite poor. With true Wratten gel filters you have to be careful about how old they are and how they've been stored. They can fade.
    No, they will fade from light and time. When Kirin was distributing B+W filters they placed a very large order for screw in glass wratten filters sandwiched in glass to the old Helix in Chicago. After a few years we took over the distribution their inventory print outs showed that they had sold very few of them and wanted us to take them back on a 2 for 1 stock balance. These were new filters in sealed B+W boxes stored in filter drawers for a few years. B+W refused our request to return them as they were special order items and all had faded over time.

  7. #17
    Drew Wiley
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    Sep 2008
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    Re: mounting gelatine filters between glass

    The official Wratten filter publication broke down the specific nature for fade risk of every single filter number with respect to three different key variables. But the problem with deep tricolor examples is that they can fade a fair amount and still look the same deep color. That means that over time they will fall out of balance and become unpredictable, without the problem possibly even being suspected except for increasingly uncooperative negatives over time. For example, with a 25, 58, 47 combination, the 25 red is rated AAA, the 58 green BBC, and the 47 blue BBB. This mean that the blue filter is likely to fade faster than the red, and the green potentially faster than either of the other two. But with old inventory, as if often the case when people purchase gel filters these days, even the starting point might be suspect.

  8. #18

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    Nov 2017
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    Re: mounting gelatine filters between glass

    The filters I'm looking at (and will try) are newly made gelatine filters. The green is out of stock and will take some time for new to be made.

    Can someone point me to measurements/articles that show that polyester films are "poor"? I'm sorry, but I have far more doubts about gelatine then polyester.
    Expert in non-working solutions.

  9. #19
    Drew Wiley
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    Sep 2008
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    Re: mounting gelatine filters between glass

    Just try using them. They're cheapo for a reason. I have a big set of Lee polyester filters than I use for mockup purposes, light balancing tests, or non-image-forming applications, never for actual photography unless the scale of reproduction is very modest, like a small casual ad picture. You'll lose image sharpness with them. Some of these are way out of whack in terms of rated density. You should really get ahold of people who have done this before and have prior experience refitting new filters, but it wasn't cheap.

  10. #20

    Join Date
    Nov 2017
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    Re: mounting gelatine filters between glass

    Quote Originally Posted by Drew Wiley View Post
    Just try using them. They're cheapo for a reason.
    Those polyester cost more than new gelatine!
    Expert in non-working solutions.

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