shutter

steve7cat · 07-01-2012, 10:13 AM

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.

Anvh · 07-01-2012, 10:23 AM

Originally posted by steve7cat

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.

Adam · 07-01-2012, 10:24 AM

I think at high shutter speeds, a mechanical one is still more precise.

**DAZ** · 07-01-2012, 11:05 AM

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.

DAZ

wombat2go · 07-01-2012, 01:42 PM

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.

kenyee · 07-01-2012, 03:19 PM

I thought the mechanical one was for the mirrorbox and the phase detect focusing mechanism?

Anvh · 07-01-2012, 04:17 PM

Originally posted by wombat2go

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?

kh1234567890 · 07-08-2012, 04:28 PM

Originally posted by Anvh

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.

Anvh · 07-08-2012, 05:48 PM

Originally posted by kh1234567890

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.

kh1234567890 · 07-09-2012, 12:50 AM

Originally posted by Anvh

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.

**TomB_tx** · 07-09-2012, 06:06 AM

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.

07-01-2012, 10:13 AM	#1
steve7cat New Member Join Date: May 2012 Location: swindon uk Photos: Albums Posts: 23	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.

07-08-2012, 05:48 PM	#9
Anvh Veteran Member Join Date: Sep 2011 Posts: 4,616	Originally posted by kh1234567890 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.

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07-01-2012, 10:23 AM	#2
Anvh Veteran Member Join Date: Sep 2011 Posts: 4,616	Originally posted by steve7cat 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
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	I think at high shutter speeds, a mechanical one is still more precise.

07-01-2012, 11:05 AM	#4
DAZ Loyal Site Supporter Join Date: Sep 2006 Location: Everett, WA USA Photos: Gallery Posts: 744	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. DAZ

07-01-2012, 01:42 PM	#5
wombat2go Veteran Member Join Date: Jan 2010 Location: Michigan Photos: Gallery Posts: 2,207	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
kenyee Veteran Member Join Date: Mar 2007 Location: Boston, PRofMA Photos: Albums Posts: 3,026	I thought the mechanical one was for the mirrorbox and the phase detect focusing mechanism?

07-01-2012, 04:17 PM	#7
Anvh Veteran Member Join Date: Sep 2011 Posts: 4,616	Originally posted by wombat2go 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
kh1234567890 Veteran Member Join Date: Sep 2010 Location: Manchester, UK Photos: Gallery Posts: 2,653	Originally posted by Anvh 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.

07-09-2012, 12:50 AM	#10
kh1234567890 Veteran Member Join Date: Sep 2010 Location: Manchester, UK Photos: Gallery Posts: 2,653	Originally posted by Anvh 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
TomB_tx Loyal Site Supporter Join Date: Jun 2011 Location: Texas Photos: Gallery Posts: 1,446	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.