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Thread: Glass neg carrier - mc optical glass

  1. #1

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    Glass neg carrier - mc optical glass

    Looking for feedback, advice, two cents etc. etc. I’m not big into DIY but I’ve cobbled together a couple of glass/registration negative carriers which work perfectly, despite being on the ugly side. I’m now looking into another glass carrier project. Forget about Newton rings etc. Off topic in this case.

    I want to use coated optical glass. In the past I worked with Schneider on this. I ended up with some MRC filter glass (from B+W) filters for a 35mm carrier. For 4x5, had to go with single coated filter glass from their MPTV division.

    I might simply go with Schneider’s stuff again, but I am exploring a few other options due to curiosity. I’d like multi-coated glass if possible. I first contacted Zeiss asking if I could get some T* coated flats. They wouldn’t entertain such a small order, but pointed me to some other companies that might. One of these is QIOPTIC. There are some others such as Edmund, PGO.

    Anyone have any experience with glass? I can’t order directly from Schott, but I assume if a company specifically lists N-BK7 they are using Schott.

    Seems like what I’m looking for are typically called “optical windows”, which are high quality borosilicate crown glasses, only flat instead of shaped into a lens element. These are not always made in the thickness you want. I need 1mm and 2mm. Then of course you usually have to choose a coating.

    I think I am totally out of my league when it comes to dealing directly with this type of supplier. That is why I would much rather if a photo company like Rodenstock or Nikon would just sell me a custom cut piece of whatever they put in their clear filters. Is that possible? Schneider was relatively easy to work with but the MPTV filters are single coated.

    Just thinking out loud. Appreciate any thoughts or experiences. Drew Wiley? Others?

    Michael

  2. #2

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    Re: Glass neg carrier - mc optical glass

    Why not explain your exact design and purpose in order to gain other's interest in the project.

    If your ideas and desires strike a chord with more users, a group may be able to work together in purchasing.

  3. #3
    Peter De Smidt's Avatar
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    Re: Glass neg carrier - mc optical glass

    I'm not sure what your application is, but there are also anti-reflection coated glass used for picture frames and for architectural purposes. For example, http://www.framedestination.com/Pict...ame-Glass.html
    "Why can't we all just get along?" President Dale, Mars Attacks

  4. #4
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    Re: Glass neg carrier - mc optical glass

    Some years back, I went through a phase of experimenting with coated glass for contact printing. I used coated glass marketed for art framing - Denglas (no longer available) or Tru Vue AR. The problem, apart from cost, was that these products tend to have imperfections that may be irrelevant for the marketed application but were a problem for me. I ended up having to search through multiple pieces of glass to get satisfactory ones, and eventually that got old both for me and for the frame shop where I was buying the stuff.

    In principle I would be interested in a source of coated or multicoated glass of assured optical quality, though I fear the cost would be very high, possibly prohibitively so depending on the size. Even if larger sizes were out of reach, I might still be interested in glass for a 4x5 carrier - a coated bottom glass would be useful for negatives that have a very smooth emulsion side. In any case, I'd certainly be happy to see someone look into this seriously, to find out what if anything is possible.

  5. #5

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    Re: Glass neg carrier - mc optical glass

    Check out Howard Glass company in Philly. They have optical glass, including Schott glass. I got some clear glass (no defects) and made a pin registration carrier. I got diamond drill bits corresponding to 21 guage cannulae, which I bought from Small Parts Inc. If you go down this route I can tell you how to drill the glass so it does not crack from the heat.

    Mike

  6. #6
    Peter De Smidt's Avatar
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    Re: Glass neg carrier - mc optical glass

    Edmund optics has some, including AR coated plastic. The latter comes up to 250mm square.
    "Why can't we all just get along?" President Dale, Mars Attacks

  7. #7
    Drew Wiley
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    Re: Glass neg carrier - mc optical glass

    Hoya does custom stuff. But I'm in agreement with Oren about coated picture glass. It's tricky to cut and edge, fragile, and I've never found it personally adequate for enlarging, though it sure beats ordinary float glass. Most of the Zeiss and other Euro glass I have, I've picked up surplus at random. That requires some luck. Coated acrylic might not stay flat under enlarger heat; but you can get it any size you wish, clear up to 4x8 ft sheets (if you have enough $$$). If you deal with Edmund, make sure its the Scientific division; they have about a thousand times as much stuff as their hobby catalog or website. Drilling glass for registration is almost hopeless if the glass is tempered. The correct type of Schott glass for that purpose allegedly isn't even made anymore. But there are other ways of positioning pins. Reminds me, I still have a tiny bit of work left on one of my 8x10 carriers; but at least the pins are in place correctly after holding my breath hoping the glass wouldn't crack in the process. The whole problem with MC is that it seem to behave like tempering and make drilling unrealistic. I should probably dig out a damaged MC filter and test again with my new specialized bits. I still have one more carrier to register; but it's for 4x5, so not an urgent project. Most of my 4x5 work doesn't need pin registration in carrier per se. Finding offset micropins is hell unless you cannibalize them from old Condit glass. My way of circumventing that is to locate one stainless micro-dowel into an exact hole, the other dowel in a very slightly oversized hole with a bit of wiggle room for the epoxy, with fully taped-down punched film strip holding the precise distance until the epoxy sets.

  8. #8
    Drew Wiley
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    Re: Glass neg carrier - mc optical glass

    ... I didn't know about Howard Glass. Looks like a great resource.

  9. #9

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    Re: Glass neg carrier - mc optical glass

    Qioptiq is Rodenstock, or at least, Rodenstock Photo Optical is one of Qioptic's divisions.

  10. #10

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    Re: Glass neg carrier - mc optical glass

    Thanks for the thoughts and suggestions so far. Apologies for the post being somewhat muddled. I'll try to clarify and give some specifics. This project or research began a few years back when I wanted to build a registration carrier for 35mm. I started to think about glass quality (especially below the negative), and the Newton ring issue. All this combined led me on this quest (I'm not much of a gear guy but occasionally I'll get a bug in my head).

    When I built the 35mm carrier, I decided I'd try to use the best glass I could reasonably get. This ended up being B+W Clear (007) MRC filters cut down to the rectangular dimensions I needed.

    At that time I was also replacing my 4x5 carrier system with an Inglis setup, and thought about having Alistair install some multicoated glass. The MRC filter glass I used in the 35mm carrier doesn't come large enough for 4x5 so I began exploring other options. Schneider Optics sent me a sample of the single coated filter glass they use to make filters in their MPTV division. I also got Tru Vue to send me 8x10 samples of all their stuff, which I thought could be interesting because while their Ultra Vue glass might be good for the bottom, some of the non-glare matte surfaces might be useful on top instead of other anti-Newton glass options. In the end I didn't have the time or inclination at the time to explore further so I just ordered the stock carrier from Inglis.

    Fast forward and I'm now looking into ordering a second carrier from Inglis, and again I'm thinking about possibly using fancy glass, at least on the bottom. Alternatively I might try to build a carrier. If I use the Inglis carrier, there are some design constraints: bottom glass 2mm, top glass 1mm, so my Schneider glass and Tru-Vue glass (or other glazing materials) can therefore only be used on the bottom.

    That's why I started thinking about looking into other suppliers that can make optical quality flats with coatings/multi-coatings. But it is all very complicated.

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