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Thread: Shutter Ideas

  1. #1

    Shutter Ideas

    All,
    Anyone have some interesting thoughts on constructing a shutter for a barrel lens ? Im thinking ahead slightly as to what I want to use on my achromat. Granted, there's always the packard shutter; but what fun is that ??
    I've seem some old shutters that resemble the one on a holga. Granted, it would be about 30x larger, but perhaps a possibility.
    Im more interested in a 'studio' type of shutter; as I can always stack on ND's for 1s + exposures (efke 25 is my friend !).
    The only thing Im truly worried about is vibration; which I think the holga-type of shutter may impose.

    Thanks again,
    Steve

  2. #2

    Shutter Ideas

    I have always wanted to attempt a shutter as in the kodakj brownie box camera (or any other) made from coke can aluminium. I suppose the holga shutter is much like it. You don't have to make it that large if you plan to shoot at small apertures... I don't think vibration would be a big problem.

  3. #3

    Shutter Ideas

    Well, after doing a quick sketch, the holga type of shutter will simply be too large to be feasible. Even if I tame the lens down to f/5.6, it would still be a pretty big piece of metal.
    I think my best bet would be to find an old packard, and making up an electronic solenoid assembly in place of the air bulb. This way, I can have somewhat more accurate times, and a broader range of speeds in the most used times (1/15, 1/8, 1/4, 1/2, B, T). Im not sure the packard would/should go much faster than 1/15th, nor do I think a small solenoid (the smaller the better, weight and vibration -wise) would do it.

  4. #4

    Shutter Ideas

    Maybe you could make a motor driven roller blind shutter to mount in front or behind the lens? I've been thinking about it and even did one lousy attempt but then had to much work and forgot about it... You try with a spring instead of a motor as well.

    I think these shutters were called thornton pickard shutters or something... Oh yes... here... http://licm.org.uk/livingImage/Shutters-Blind.html They are the a lot like the speed graphic (I think) focal plane shutters, but using them near the lens makes even larger formats possible.

  5. #5

    Shutter Ideas

    I thought about the motor idea. It would be easy to do it with a wind spring. My idea was to always have the spring in tension, with a tick mark on the wheel. Cock the shutter and let it go = instant exposure time. The purpose of the tick mark on the rotor wheel would be to stop the rotor with a small block when the opening was lined up wtih the barrel, this allowing a 'time' exposure and viewing/focusing.
    The problem wtih that design is that the rotor has to be at least 2.25x the size of the largest f/stop. On a 230mm focal length lens with a 4.0 f/stop, that's a hell of a piece of brass.

  6. #6

    Shutter Ideas

    Steve, a homemade shutter has been on my list of projects for some time. For my purposes, it would be used for an improvised lens box camera. The large frontal surface area of the box should provide enough room for installing a home-built shutter even as crude as a rubber band or spring powered rotating disk, with variable width pie-shaped opening. Or a horizontally sliding, spring-actuated guillotine shutter with variable width opening.

    Several years ago I experimented with a gravity powered, vertically oriented guillotine shutter, using a lead weight to actuate the metal slide. I was able to measure shutter times of around 1/15th sec, but never actually put the design into practice, since a vertically falling shutter is effected by the angle at which the camera is tilted, therefore the shutter time would be modulated by the angle of the camera tilt. Hence the idea of a horizontally moving, spring-actuated shutter.

  7. #7

    Shutter Ideas

    Joe,
    I thought about the guillotine shutter idea as well; mainly just as a studio shutter sort of thing. My idea had 'wings' that opened up on either side of the shutter barrel, using a simple lever mounted ontop of the barrel.
    Unfortunately, either way, the most simple and effective idea would still be to find a busted packard shutter, and modify it to use an electronic solenoid.
    About the blind shutter; how would you set it for focusing ? Have any of you gotten a chance to actually look inside of one ?

    Thanks again !

  8. #8

    Shutter Ideas

    'blind' type, as in roller blind, or cloth focal plane shutter?

    I can tell you what a Speed Graphic one looks like.

    Imagine a length of opaque cloth attached to to spools (like a roll of film).

    Part way into the roll, followig an opening-free 'leader' of shutter fabric, analogous to, say, 'exposure 1 or 2 ', there is a rectangular slot cut in the fabric, and supported with a thin metal band to keep it from fraying ,etc. A little bit further into the roll, say exposure 4, is another slot, wider than the first. They are spaced by a bit more than the width of one exposure, say rough guess (actually no idea) 6" for a 5" film window. The continues to almost the end of the fabric, where there is a giant opening that will expose the entire sheet of film at once...same size as back of camera. Thsi is I guess the 'T' setting. I believe there is no 'B' as it isn't practical with th emovement of such a shutter. After the full opening is another final length of slot-free fabric that covers the film plane.

    The whole thing is wound up so that at maximum tension, the first slot whizzes by the film plane, with the shortest opening and highest winding tension resulting in a very fast shutter speed (1/1000 on Speed Graphic). I think the narrowest slot on my 4x5 SG shutter is about 1/8" long.

    I don't know the exact spacing, but there is enough between slot openings so that the film plane is covered again after each shutter firing.

    Say you wind it all the way to 1/1000 and fire it. Some of the tension is unwound, and it's actually cocked & ready for the next slower speed (actually ,there is a high/low switch so the speeds are stagggered every other speed, I think in the following order 1/1000, 1/250, 1/60, flip the switch and 1/500, 1/125, 1/30) appear in the window indicator.

    After firing at 1/1000, if you want another shot at 1/1000, you have to rewind the shutter to full tension.

    To focus, or use a lens with its own shutter, or do long exposures you use T and fire the shutter so it stays open.

    To totally release the shutter tension you fure it as many times as necessary to get all the way wound back up...say 1/1000, 1/250, 1/160, T, end.

  9. #9

    Shutter Ideas

    Mamiya does something similar with the older 645 cameras, but it uses two shutter curtains and fires them in a timed fashion to produce the correct traveling slit to expose the film. They work great until they need service, then they are almost always a write off. Sounds like the Speedgraphic would be easier to service than the Mamiya.

  10. #10

    Shutter Ideas

    All,
    I think a curtain would be too complex/too delicate of a shutter idea to start out with, and to mount in front of a lens. I am thinking of a falling leaf sort of shutter, that shouldn't be too large.
    We'll see what the sketch looks like; then hopefully you all can tell me what you think.

    -Steve

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