notontv
Leisure Classist
I've been searching for a week, but can't find any good info on this so I thought I would go to the best photo resource I know 
How do you make the shutter stay open for a set amount of time? I am not in fact making a camera, but would like to borrow the technology to activate solenoids on an organ staircase piece of art that I am making :bang: of course you could do it with electronic/computer bull, but I would love an analog mechanism. any thoughts?
How do you make the shutter stay open for a set amount of time? I am not in fact making a camera, but would like to borrow the technology to activate solenoids on an organ staircase piece of art that I am making :bang: of course you could do it with electronic/computer bull, but I would love an analog mechanism. any thoughts?Landshark
Well-known
Depends what kind of interval. and whether you need repetition
Depends on a bunch o' stuff. Older cameras with leaf shutters rely on a gear train and location on a cam to retard the timing.
SLR's with a focal plane shutter are similar and mechanically delay the release of the second curtain. Electronic FP's use an electronic timing circuit to do the same.
Something like a clock where you could have contacts built into the hands or contact wheel making contact with another contact mounted in the clock face might be easier.
Connect up to the second hand if you want a one minute time, add more contacts for shorter times.
Depends on a bunch o' stuff. Older cameras with leaf shutters rely on a gear train and location on a cam to retard the timing.
SLR's with a focal plane shutter are similar and mechanically delay the release of the second curtain. Electronic FP's use an electronic timing circuit to do the same.
Something like a clock where you could have contacts built into the hands or contact wheel making contact with another contact mounted in the clock face might be easier.
Connect up to the second hand if you want a one minute time, add more contacts for shorter times.
notontv
Leisure Classist
I would like it to be something like a shutter in that the 'player' would hit a switch that would open the air flow and the timer would keep it open for a set amount of time. The clock would be a fun way to automate it though. Any idea where I can find drawings of these mechanical systems?
danielmk2
Member
As what I've learned from different documents, The "thing" that counts the time, we call it escapement. The escapement is used in all the shutters, but may not work for all shutter time.
For leaf shutters, all the shutter time is determined by the escapement (but some uses a special spring without escapement for the highest speed, like de earlier compur), there is an adjustable little "thing"(I forgot the name in english) that can determine the time that the escapement release the lever or cam.
Just as Landshark said, for mechanical focal shutters, for example Leica, the escapement only work for 1s-1/30 (nearly the same principle as that for leaf shutter). From 1/50 (flash sync) and higher speed, the exposure time is determined by the distance between the curtains. That means there is a cam linked with the axis of the first curtain. When the first curtain travels to a certain position, the second curtain release lever will be triggered by the cam, then the second curtain begins to release.
Hope that it helps.
For leaf shutters, all the shutter time is determined by the escapement (but some uses a special spring without escapement for the highest speed, like de earlier compur), there is an adjustable little "thing"(I forgot the name in english) that can determine the time that the escapement release the lever or cam.
Just as Landshark said, for mechanical focal shutters, for example Leica, the escapement only work for 1s-1/30 (nearly the same principle as that for leaf shutter). From 1/50 (flash sync) and higher speed, the exposure time is determined by the distance between the curtains. That means there is a cam linked with the axis of the first curtain. When the first curtain travels to a certain position, the second curtain release lever will be triggered by the cam, then the second curtain begins to release.
Hope that it helps.
notontv
Leisure Classist
ahh, knowing that it's called an escapement helps a lot. thanks. In the end, I would make something in the 5-15 second range
peterm1
Veteran
And of course its important to understand, if you do not already, that at low shutter speeds the shutter completely opens (curtain 1) and then curtain 2 is triggered to close behind it at the appropriate moment . At higher speeds correct timing can only be achieved by shutter curtain 1 opening and then shutter curtain 2 quickly followiwng behind it. This creates a slit travelling across the face of the image so that (say) 1/1000 of a second any one bit of the film is correctly exposed for that amount of time - even though the entire shutter process takes much longer overall. This is the only way focal plane shutter mechanisms can create such fast shutter times. Of couse this was much more of an issue in the days of mechanical camera mechanisms and cloth shutter curtains. And its why there is a limit on flash sync speeds - flashes only illuminate the entire frame if at some point the entire frame is open. So they only work properly at lower ahutter speeds. becsause that is how shutter operate at low speeds.
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