Framing 35mm slides for projection

Discussion in 'Miscellaneous Equipment' started by Matus Kalisky, Feb 17, 2012.

  1. Matus Kalisky

    Matus Kalisky Subscriber

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    Hi, I have just visited my friend who has Leica Pradovit 300 IR projector (with the 90/2.5 lens). It was really a treat, but it was not possible to get the whole image sharp. As the wall was flat :wink: I have check a few of the slides and indeed one could see a slight "bulging" of the film in the frames - maybe around 1mm - but it was obviously enough to cause problems.

    Just a note - he is using glass-less mounts of "newer" type whatever that means - definitely compatible with his projector.

    So - I would like to ask - how do you make sure that your framed slides are nicely flat? Glass mounts? Special mounting? Are some particular mount more suitable than others?

    I am asking as I may finally get a 35mm camera just to be able to project slides - it really looks cool (No, I do not plan to get into projecting 6x6 slides as of now)

    thanks
     
  2. benjiboy

    benjiboy Subscriber

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    What you describe is called " popping" and is caused by the heat of the projector lamp, I mount my slides both 35mm and 120 in Gepe glass mounts to avoid this http://www.amazon.co.uk/Gepe-Glass-...PM9Y/ref=sr_1_2?ie=UTF8&qid=1329482529&sr=8-2, but as with all slides you have to be careful not too leave them on the screen for too long if you don't want to "fry" the slides .
     
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  3. spijker

    spijker Subscriber

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    I agree with benjiboy. Popping slides is an old problem with slide projecting. Various manufacturers tried to come up with glass-less solutions that allowed more movement of the film inside the frame so the film can expand without bulging/popping. But in my experience only the glass slide frames solve the problem. The Gepe AN glass frames have anti-newton glass (=slightly matted) to avoid anti newton rings and don't seal the film completely from the air which supposedly prevents mold on the film in the long run. The Gepe glass frames are more expensive but in my opinion well worth the money.

    Also available here.
     
  4. ic-racer

    ic-racer Member

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    The Gepe slide mounts with glass don't squish the film flat like a glass negative carrier. Although the literature does not say, I suspect the Leica lenses are curved field to account for that. Was the projector perpendicular to the wall? I the projector was aimed up to the wall, it won't all be in focus unless you use the PC-ELMARIT-PRO (perspective correction) projector lens. Otherwise prop the projector up in height so it is level with the middle of the screen and see if the focus is better.
     
  5. Matus Kalisky

    Matus Kalisky Subscriber

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    Thanks. Seems like glass frames would be a solution.

    - ic-racer -
    No - it was not problem of plann-paralelity between screen and slides - as one could either focus on the center of the slide and have edges unsharp, or the other way round. Still - this experience forced me again to look as some 35mm camera to be used exclusively with slides :smile:
     
  6. silveror0

    silveror0 Member

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    There is another solution that will help, and that is to use an auto-focus projector. When the slide pops out of focus due to heat from the bulb, the projector will instantly re-focus and maintain sharpness over the whole image.

    Back when I projected slides, using two projectors with a professional controller for lap dissoves/cuts/etc and synchronized with sound track, I used a pair of Kodak Ektagraphic AF-2 (auto-focus) projectors with zoom lenses. They were set up to project onto a 70x70-inch lenticular screen that could be tilted at the top toward the projectors (to eliminate the "keystone" distortion of the image), and the zoom lenses could be adjusted so that the projected images were perfectly superimposed. While one projector was showing a slide, the other projector had a slide in position being pre-warmed by its bulb, so that any slide being projected had already been "popped" before being seen on the screen.
     
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  7. benjiboy

    benjiboy Subscriber

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    IMO A/F Projectors are not the answer because the heat of projection lamp in popping the slide causes it to bow and the all over sharpness on re-focusing will not be the same across the projected image, glass mounts keep the slides surface flat between the glass, this is even more apparent with 6X6 120 film slides.