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07-01-2012, 10:13 AM   #1
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shutter

In this age of electronics why do we have a mechanical shutter? surely the sensor could be turned on and off electronically.
Just a thought.

07-01-2012, 10:23 AM   #2
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QuoteOriginally posted by steve7cat Quote
surely the sensor could be turned on and off electronically.
Just a thought.
They could but if they do that all the information the "pixels" are holding will be lost.
07-01-2012, 10:24 AM   #3
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I think at high shutter speeds, a mechanical one is still more precise.
07-01-2012, 11:05 AM   #4
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Sensors can and do have “electronic” shutters. Most of the digital sensors made (by numbers manufactured) don't use a mechanical shutter. The problem with a electronic shutter is even thou electronics are fast it is not instantaneous. While the analog information is being digitized light is still falling on the sensor. This can add all kinds of problems like more noise, light smearing into other pixels and the data from different parts of the sensor being digitized at different times. The last can make for strange defects for moving objects. Having a mechanical shutter freezes the light (as in no more light can get to the sensor) then the data can be digitized with out any new light interfering. For video some of these problems can and are more tolerated but with still photos the people that typicality use DSLR cameras demand as high a quality as they can afford.


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07-01-2012, 01:42 PM   #5
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Yes I also wonder how long the mechanical shutter will last. It is complicated on a mirrorless because the focal plane shutter has to be put up. activated then taken away again.
For dslr which have high iso capability, It may be something to do with stray light in the barrel because sensors are presently so reflective. Maybe the non reflective shutter curtains reduce the amount of stray light bouncing around in there.
07-01-2012, 03:19 PM   #6
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I thought the mechanical one was for the mirrorbox and the phase detect focusing mechanism?
07-01-2012, 04:17 PM   #7
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QuoteOriginally posted by wombat2go Quote
Yes I also wonder how long the mechanical shutter will last. It is complicated on a mirrorless because the focal plane shutter has to be put up. activated then taken away again.
For dslr which have high iso capability, It may be something to do with stray light in the barrel because sensors are presently so reflective. Maybe the non reflective shutter curtains reduce the amount of stray light bouncing around in there.
LCD shutter, the same one use in active 3D glasses for example might be the future.
Only problem is their current speed, 1/1000, maybe it's fast enough for medium format camera's?
07-08-2012, 04:28 PM   #8
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QuoteOriginally posted by Anvh Quote
LCD shutter, the same one use in active 3D glasses for example might be the future.
Only problem is their current speed, 1/1000, maybe it's fast enough for medium format camera's?
It is not so much the speed (1/1000s is achievable with pi cell arrangement) as contrast ratio and viewing angle problems - you basically end up with a lot of stray light going through. Also because of the polarisers you only get 50% light transmission at best. One of the reasons why 3D cinema and TV is so annoyingly dim.

07-08-2012, 05:48 PM   #9
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QuoteOriginally posted by kh1234567890 Quote
It is not so much the speed (1/1000s is achievable with pi cell arrangement) as contrast ratio and viewing angle problems - you basically end up with a lot of stray light going through. Also because of the polarisers you only get 50% light transmission at best. One of the reasons why 3D cinema and TV is so annoyingly dim.
You want one?
http://www.liquidcrystaltechnologies.com/products/LCDShutters_2.htm

But yeah pi-cell is problematic.

Sony has a 960hz LCD monitor, no idea what they use.

Last edited by Anvh; 07-08-2012 at 05:58 PM.
07-09-2012, 12:50 AM   #10
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QuoteOriginally posted by Anvh Quote
You want one?
Kerr cells will give you nanoseconds. Not sure that the public would take to cameras filled with nitrotoluene and 10+ kVs of drive voltage. It's been a long time since my Physics degree when I made one, but I remember the stuff being pale yellow. Smelled nice though. You are still stuck with polarised light however.
07-09-2012, 06:06 AM   #11
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I hear of a lot more electronics problems in cameras than mechanical issues with well-proven mechanisms. My 1930s Leica shutter still works fine after a few generations of users, and my all-mechanical Pentax cameras are more reliable than the later models with electronics, although most of the "electronic" problems I've seen have been switches and connections that have mechanical action.
However, point is valid that mechanical film cameras never saw the sheer volume of exposures that some put on their dSLRs. As development and technology continue the electronic reliability should go up, while mechanical is likely to go down because mechanical expertise is less valued now that products are mainly electronic.
Product design teams for things like cameras used to be headed up by mechanical engineers; while today the heads are electronic (digital) types who view mechanical design as primitive. And analog electrical designers are disappearing fast also.
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