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View Full Version : Shutterless camera, why not!?


aaronrider
6th of August 2007 (Mon), 01:49
Ok,

Im no expert, but I just dont see why they cant make a shutterless camera!

Of course with film you cant because it needs a shutter to keep the light from hitting the film...but why cant they do this with digital simply by turning the sensor off and on. They can make it so the sensor will turn on for a short duration ( 1/2500th for instance) to collect the light data, then turn back off and be done with the exposure. I dont see whats holding them back from doing this?

Just imagine not having to work with any shutter curtains. Flash photography without those darn max shutter syncs would be amazing! It would be so much easier and simpler. No shutter lag or anything. Not to mention you will never having to worry about wearing out your shutter.

BradT0517
6th of August 2007 (Mon), 01:54
Well there would still be shutter lag, but instead it would be called sensor awareness lag.

Hermeto
6th of August 2007 (Mon), 01:55
Shutterless cameras - with their own set of problems - already exist.
They are called P&S..

davesrose
6th of August 2007 (Mon), 01:58
We'd never hear the end of it from people complaining of dust on their sensors!!!!!!!!!!! ;):D

That, and maybe sand or dirt if they're changing lens in at an awkward location.

Roy P
6th of August 2007 (Mon), 02:56
The original 1D sensor does act as a shutter for faster speeds, the mechanical shutter being a 'protective cover' and used for slow speeds.

aaronrider
6th of August 2007 (Mon), 03:20
As for the dust, they can still have a cover over it that will open the moment you press the shutter half way to focus. By the time your ready to take the shot it will be fully open and ready to expose. I dont think dust will really be much more of a problem?

This would be nice because you will always be able to use the flash in normal mode without high speed sync screwing everything up

aaronrider
6th of August 2007 (Mon), 03:24
The original 1D sensor does act as a shutter for faster speeds, the mechanical shutter being a 'protective cover' and used for slow speeds.

Hmm, ok

Why does it have a max flash sync of 1/500th? Shouldnt it be able to sync at any speed then?

Roy P
6th of August 2007 (Mon), 03:59
Afraid I can't give you answer on the flash synchro as I dont use flash, seems reasonable question though.

But from BeBit found following from 1D original sales blurb:

Typehttp://web.canon.jp/imaging/EOS1D/imgs/top_imgs/shim.gifElectronic shutter with the CCD sensor and vertical-travel,
focal-plane shutter with all speeds electronically-controlled Shutter speeds 1/16000 to 30 sec. (1/3-stop increments), bulb,
X-sync at 1/500 sec.
Shutter release Soft-touch electromagnetic releaseNoise reduction for long exposures Operates at 1/15 sec. or slower shutter speeds (including bulb)
Self-timer 10-sec. or 2-sec. delay.
Remote control Remote control with N3 type contact

StewartR
6th of August 2007 (Mon), 06:38
I don't think an electronic shutter, like P&S cameras have, would be the panacea in terms of flash sync speed that you seem to think it would.

A sensor is essentially a huge array of tiny little buckets which capture photons falling into them. The mechanical shutter is like a lid that covers the buckets. So it's easy to see how the process works: open the lid, close it again, count how many photons you captured in each bucket, and then pour them all away so that you're ready to take the next shot. (In fact it would probably be easier to count them as they're poured out.) You've got about 8 or 10 million buckets to count, but a relatively long time in which to do this: the lid won't be ready to close again for at least 1/10th of a second.

Now, how does this work with an electronic shutter? The buckets don't have a lid but are permanently open. Photons are falling into them all the time. How do you take an exposure? It seems to me that you have to empty the buckets at the start of the exposure, then empty them again, and count the photons, at the end of the exposure. But if your exposure is only (say) 1/1000th of a second, then you have to empty each bucket twice within 1/1000th of a second. Doing that for one bucket is obviously possible. Doing it for 8 or 10 million buckets presents something of a challenge.

We know that the flash sync speed of conventional DSLRs is limited by the speed at which the shutter curtains move. However, the Canon S5 IS is state-of-the-art P&S, and it has a maximum flash sync speed of 1/250th, which is comparable to Canon DSLRs. Not 1/1000th.

I think what this is telling us is that it takes around 1/250th of a second to empty all the buckets. So when you take a picture at 1/1000th, what happens is that the camera needs to start emptying buckets for the second time (and counting the contents) before it's finished emptying all the buckets for the first time (and thereby priming them for use). This is exactly analogous to the situation with a mechanical shutter, whereby the buckets are exposed to the incoming stream of photons at different times.

If you use a DSLR to take a picture of a fast-moving object (e.g. a golf club mid-swing) with a shutter speed faster than the maximum sync speed, you get a tell-tale distortion of the object because not all pixels are exposed at the same time. I expect you would get a similar distortion using a P&S. Can anybody confirm?

vondo
6th of August 2007 (Mon), 10:15
I've wondered this too and if the high shutter speeds are possible (maybe they aren't per the discussion above) it would seem to me to make sense to have a shutter (protective cover) that was only over the sensor when the camera was turned off or no lens was connected to the body.

Since wearing out the shutter seems to be a major cause of death of these cameras, this could really extend the life of the camera, it would seem.

poloman
6th of August 2007 (Mon), 10:20
Shutter replacement is approx. $250. I wouldn't call that death, just inconvenient. It might encourage you to do that upgrade you were wanting to do anyway.

Cyth0n
6th of August 2007 (Mon), 10:22
I've always wondered this. We spent ages debating the question of why DSLRs need a shutter on another forum and the best responses we could come up with were "becuase it makes a cool sound," "because someone who is much more clever than us decided it should," and "so that we have to pay to have it replaced every so often and we might spend more money on a new camera if it dies."

It would be great if somone could set the record straight.

vondo
6th of August 2007 (Mon), 10:25
Shutter replacement is approx. $250. I wouldn't call that death, just inconvenient. It might encourage you to do that upgrade you were wanting to do anyway.

Well, on a Rebel-level camera, I'd call that "death." On my 20D, it's close. Clearly for those of you with the 5D or 1D, it's maintenance. :lol:

JMHPhotography
6th of August 2007 (Mon), 10:28
Ok,

Im no expert, but I just dont see why they cant make a shutterless camera!

Of course with film you cant because it needs a shutter to keep the light from hitting the film...but why cant they do this with digital simply by turning the sensor off and on. They can make it so the sensor will turn on for a short duration ( 1/2500th for instance) to collect the light data, then turn back off and be done with the exposure. I dont see whats holding them back from doing this?

Just imagine not having to work with any shutter curtains. Flash photography without those darn max shutter syncs would be amazing! It would be so much easier and simpler. No shutter lag or anything. Not to mention you will never having to worry about wearing out your shutter.

It's already been pointed out... shutterless cameras already exsist. P&S cameras already do everything you just described. Also pointed out, they are not problem free.

StewartR
6th of August 2007 (Mon), 10:38
I've always wondered this. We spent ages debating the question of why DSLRs need a shutter on another forum and the best responses we could come up with were "becuase it makes a cool sound," "because someone who is much more clever than us decided it should," and "so that we have to pay to have it replaced every so often and we might spend more money on a new camera if it dies."

It would be great if someone could set the record straight.I've already suggested "because electronic shutters can't work fast enough to give the high sync speeds everybody wants".

And how about "because keeping the sensor on all the time will increase heating of the components and increase noise levels".

And come to think of it, what's actually wrong with "because someone who is much more clever than us decided it should"?

René Damkot
6th of August 2007 (Mon), 10:43
Hmm, ok

Why does it have a max flash sync of 1/500th? Shouldnt it be able to sync at any speed then?

It doesn't and it is...
Like I said here. (http://photography-on-the.net/forum/showpost.php?p=3668014&postcount=11)

*As long as the 1Dino doesn't know there is a flash attached* (for instance when a strobe is used, or a flash that doesn't have ETTL, so doesn't communicate with the camera) the flash will be synced at all speeds.

Strobist posted something about the D70 a while back, which works similair.
Another thread: Click (http://photography-on-the.net/forum/showthread.php?t=325675&highlight=HSS&page=2)

Mark_Cohran
6th of August 2007 (Mon), 10:45
http://photography-on-the.net/forum/showthread.php?t=271083

http://photography-on-the.net/forum/showthread.php?t=32267

Two previous threads on the subject.

Mark

CyberDyneSystems
6th of August 2007 (Mon), 10:50
Hmm, ok

Why does it have a max flash sync of 1/500th? Shouldnt it be able to sync at any speed then?

Only 1/500?

It was the 1D's unique ability to use the CCD sensor as a shutter that made it the first and only Canon DSLR and the first DSLR to achieve a 1/500th flash sync and the only Canon DSRL to offer 1/16000 shutter speed.

One of the few draw backs of the CMOS is that it is not a good choice (at thsi time_ for being used as a defacto shutter by switching it on and off, they don't work that fast (yet)

CCD on the other hand is and has been capable of this feat,.

CyberDyneSystems
6th of August 2007 (Mon), 10:55
I've always wondered this. We spent ages debating the question of why DSLRs need a shutter on another forum and the best responses we could come up with were "becuase it makes a cool sound," "because someone who is much more clever than us decided it should," and "so that we have to pay to have it replaced every so often and we might spend more money on a new camera if it dies."

It would be great if somone could set the record straight.

Because for now the only cost effective way to get a shutter speed above say 1/2000th is to use a mechanical shutter.

aaronrider
6th of August 2007 (Mon), 12:46
Hmm, well ok it looks like this type of shutter may pose a few problems, but im guessing it may be something we will see more on future cameras once they can get the bugs worked out?

Ane yes, the 1/500th flash sync is ok for most applications, but the 1/250th is too for many things

Cyth0n
6th of August 2007 (Mon), 13:58
And how about "because keeping the sensor on all the time will increase heating of the components and increase noise levels".

You wouldn't need the sensor on all the time. Just turn it on when the exposure is made. In the same way that I assume that it works at the moment.

And come to think of it, what's actually wrong with "because someone who is much more clever than us decided it should"?

Because if we don't ask questions and challenge them then we don't get to be as clever as them. :p

Because for now the only cost effective way to get a shutter speed above say 1/2000th is to use a mechanical shutter.

Well this seems to makes sense but I was under the impression that the 1 series could only achieve 1/64000 through the use of electronic trickery. It just goes against the grain of electronics being faster than mechanics. As you say though, it all comes back to cost.

adas
6th of August 2007 (Mon), 14:49
P&S cameras still have mechanical shutter consisting in one curtain, rather than two like in DSLRs.
This curtain covers the sensor (it's located inside the lens) to finish the exposure time, and to allow the buckets to be read in darkness.

Ofcourse there are shutterless cameras too, delivering the worst image quality, the cellphone cameras or very cheap CMOS pocket cameras.

Tom W
6th of August 2007 (Mon), 15:14
And come to think of it, what's actually wrong with "because someone who is much more clever than us decided it should"?

Blasphemy! :D :D

Delleps
7th of August 2007 (Tue), 00:54
I'm surprised no one has mentioned the obvious (and ubiquitous) video camera. The CCD or CMOS sensor in some of these units capture both video frames and still photo frames. I should think that shortly (1-3 years?) we'll see "solid-state" DSLRs with electronic shutters (gates) and pellicle mirrors (remember the Canon Pellix?) that will be as silent as the Leica rangfinders. No mirror flop and ultra-high frame rates. Maybe the TTL capability will be replaced by remote, "live-view" ultra-high resolution viewfinders that look like and are worn like sunglasses. (Who can say "Borg"?)

The difference between video and still-image cameras may disappear entirely as our new cameras will be capable of capturing both.

My guess is that eventually the problem of smaller sensors being less sensitive and noisier will be resolved. Cameras and lenses will shrink while sensor ISO ceilings and resolution go up.

We live in interesting times.

Glenn NK
7th of August 2007 (Tue), 02:11
I don't think an electronic shutter, like P&S cameras have, would be the panacea in terms of flash sync speed that you seem to think it would.

A sensor is essentially a huge array of tiny little buckets which capture photons falling into them. The mechanical shutter is like a lid that covers the buckets. So it's easy to see how the process works: open the lid, close it again, count how many photons you captured in each bucket, and then pour them all away so that you're ready to take the next shot. (In fact it would probably be easier to count them as they're poured out.) You've got about 8 or 10 million buckets to count, but a relatively long time in which to do this: the lid won't be ready to close again for at least 1/10th of a second.

Now, how does this work with an electronic shutter? The buckets don't have a lid but are permanently open. Photons are falling into them all the time. How do you take an exposure? It seems to me that you have to empty the buckets at the start of the exposure, then empty them again, and count the photons, at the end of the exposure. But if your exposure is only (say) 1/1000th of a second, then you have to empty each bucket twice within 1/1000th of a second. Doing that for one bucket is obviously possible. Doing it for 8 or 10 million buckets presents something of a challenge.

We know that the flash sync speed of conventional DSLRs is limited by the speed at which the shutter curtains move. However, the Canon S5 IS is state-of-the-art P&S, and it has a maximum flash sync speed of 1/250th, which is comparable to Canon DSLRs. Not 1/1000th.

I think what this is telling us is that it takes around 1/250th of a second to empty all the buckets. So when you take a picture at 1/1000th, what happens is that the camera needs to start emptying buckets for the second time (and counting the contents) before it's finished emptying all the buckets for the first time (and thereby priming them for use). This is exactly analogous to the situation with a mechanical shutter, whereby the buckets are exposed to the incoming stream of photons at different times.

If you use a DSLR to take a picture of a fast-moving object (e.g. a golf club mid-swing) with a shutter speed faster than the maximum sync speed, you get a tell-tale distortion of the object because not all pixels are exposed at the same time. I expect you would get a similar distortion using a P&S. Can anybody confirm?

Good description and analogy.:)

Your later comment about clever people making the best of current technology needs to be kept in mind when "we" start re-designing cameras and second guessing experts in electronics.;)

Lani Kai
7th of August 2007 (Tue), 02:42
Electronic shutter makes the sensor more prone to smear and sensor blooming.