Shutter on P&S cameras

iskoos

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Some say P&S cameras don't have shutter. That's not true. Or maybe they say some of them don't have it. I have seen and owned a few P&S yet never seen one without a mechanical shutter.
The ones I currently have Canon A70 (very old) and A640 have some sort of mechanical center shutter (must be a leaf shutter).

I observed it very closely and the shutter is normally open(due to constant live view). It stays open during the exposure but it closes after the exposure ends while the camera processing the picture. Do you know why?

And the second question is that do you know any P&S camera that doesn't have a mechanical shutter? Like camera cell phones...
 
I think you may be mistaken. :scratch:
 
I just checked on a Nikon P&S camera I have here, and I do see something that looks like a shutter...go figure :blushing:

I can't tell, but if it closes after the exposure, then it can't really be a true photographic shutter. But if it closes to end the exposure, then it really is the camera's shutter.
 
I just checked on a Nikon P&S camera I have here, and I do see something that looks like a shutter...go figure :blushing:

I can't tell, but if it closes after the exposure, then it can't really be a true photographic shutter. But if it closes to end the exposure, then it really is the camera's shutter.

Yep!.. When I did this test, I was so sure that I wasn't going to see any mechanical(physical object) shutter that would close the aperture hole but I did and this surprized me. And I timed it; picked a long exposure (like 10 sec.) and counted the seconds while pointing a flashlight into the lens so I can see what's going on. At the end of the selected exposure time, bam!.. something closed the hole... Camera then took a few more seconds to finish what it was doing (live view was unavailable all this time) and then restores the live view.

I searched the web for hours basically but couldn't find enough info about it...

I will see if somebody chime in on this...
 
Actually MOST P&S cameras don't have a mechanical shutter. I think you may be confusing the shutter with another very important part in the camera. The key alarm bell for me rang when you said "leaf".

You may be getting the aperture mechanism in the lens confused with the shutter. All P&S cameras have some kind of aperture mechanism in the lens, but very few have shutters. For the most part they add cost and a heck of a lot of complexity to a very simple device. Or you may not. If as you say it closes after the exposure it's likely to be a shutter mechanism.

Now that said there are some P&S cameras that do have shutters for an important image quality reason. CCDs (or was it CMOS, I can't remember now but I think CCDs) required that the sensor data is read out in the dark. I think this was to prevent the phenomenon called blooming which has a small but noticeable affect on the image quality. You will typically find these shutters in high-end point and shoot cameras.

I've pulled apart a few very cheap Olympus cameras over the years (we're talking sub $150) and none of them had a mechanical shutter. Can't for the life of me remember the model numbers though.
 
Actually MOST P&S cameras don't have a mechanical shutter. I think you may be confusing the shutter with another very important part in the camera. The key alarm bell for me rang when you said "leaf".

You may be getting the aperture mechanism in the lens confused with the shutter. All P&S cameras have some kind of aperture mechanism in the lens, but very few have shutters. For the most part they add cost and a heck of a lot of complexity to a very simple device. Or you may not. If as you say it closes after the exposure it's likely to be a shutter mechanism.

Now that said there are some P&S cameras that do have shutters for an important image quality reason. CCDs (or was it CMOS, I can't remember now but I think CCDs) required that the sensor data is read out in the dark. I think this was to prevent the phenomenon called blooming which has a small but noticeable affect on the image quality. You will typically find these shutters in high-end point and shoot cameras.

I've pulled apart a few very cheap Olympus cameras over the years (we're talking sub $150) and none of them had a mechanical shutter. Can't for the life of me remember the model numbers though.

Thank you Garbz for taking time to reply. I would say I am pretty sure I am not confusing the aperture mechanism with what I think may be the shutter leaf. I can clearly see the aperture mechanism in the very back of the lens when I look up closely. Especially when the lens zooms in, it is much easier to see due to the magnification. It opens up and closes in circular motion just like an iris of a human eye. The other leaf (which I think might be the shutter but probably is not) that I am talking about closes in front of it. It is very fast and hard to follow. But it feels it starts from one side and goes all the way to other side (like a curtain) till it closes the lens opening etirely.
Take a P&S camera and see it for yourself. I am pretty sure Mike did see the same thing on his Nikon P&S!..
That is NOT the aperture mechanism!..

On the other hand what you said in your 3rd paragraph makes sense. It could be the very reason why this mechanical part closes the lens opening after the exposure taking. If the sensor data needs to be read out in total darkness, there I have the answer why that piece closes the lens opening. But again the lens gets closed with something other than the aperture mechanism. I am sure of it. It is NOT the aperture mechanism that closes the lens. At least in my Canon P&S cameras...
 
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I also thought, at first, that there might be some confusion with the aperture blades...but no, I'm seeing an actual curtain travel vertically and close up the lens, in front of the aperture blades...but only after the exposure.

Maybe it does have to do with CCD sensor needing dark as the date is pulled off the sensor. :scratch: (I don't know which, but it would make sense the it's CCD, not CMOS)
 
Both of my Canon P&S cameras have CCD in them. So I guess I found the answer to my question in this thread. If CCD needs darkness to process the data, that cutain just does that.
This is the reason why I love internet forums so much...:)
 
Needs, no. There are image improvements especially in high contrast situations to having a dark readout, but a CCD does not strictly need a shutter.

Also "take a P&S and see for yourself" is a misnomer. As I mentioned before many of them have very different designs. The camera which I ripped to pieces was an Olympus C310Z that definitely had no shutter since after I failed with the IR conversion I decided to completely! dismantle it and count the number of components. Surprisingly simple device. On the flip side, my dad's Olympus C-730 bought about 5 months earlier but a higher quality camera does have a mechanical shutter which reacts just as you describe (closes for readout).
 
Needs, no. There are image improvements especially in high contrast situations to having a dark readout, but a CCD does not strictly need a shutter.

Also "take a P&S and see for yourself" is a misnomer. As I mentioned before many of them have very different designs. The camera which I ripped to pieces was an Olympus C310Z that definitely had no shutter since after I failed with the IR conversion I decided to completely! dismantle it and count the number of components. Surprisingly simple device. On the flip side, my dad's Olympus C-730 bought about 5 months earlier but a higher quality camera does have a mechanical shutter which reacts just as you describe (closes for readout).

Himmm... You confused me a bit with your above comment to be honest. First of what is "Needs, no."? I didn't understand what you were refering to with that.

Second, why is it misnomer to say "take a P&S and see for yourself"? I just wanted you to see that what I was talking about is NOT the aperture mechanism as you thought I was thinking. Based on what I have seen so far (and also Mike saw the same thing), many (means not all of them) of the P&S cameras will likely have similar mechanism. So if you had one handy, there would be a good chance that you would see that curtain. And if you wouldn't see that curtain then, you would just tell us that the one you have doesn't have that mechanism.
And the last thing I am confused is the statement about your dad's C-730. You are saying it has a mechanical shutter just like I described. Are you calling that curtain a shutter now? Because I was convinced that what I saw wasn't a shutter mechanism. At least it wasn't something to end the exposure.
Well, the only purpose of this post is to find out what is right and what is not. That's all I am after...
 
To clarify. What I mean is that a camera with a CCD sensor does not strictly need a shutter or mechanism that allows readout to occur in the dark. It's a nice to have feature for the image improvements but it's not critical to create a functioning camera.

The misnomer is just that the very first camera example I gave was one which didn't have a shutter, so I can't just pick up "a" P&S camera to see what you're talking about, I'd need to pick up one with a shutter. :lol:, anyway kind of a moot point so late in the thread.

My dad's C-730 had something as you described. In this case it looks to be behind the aperture blades. I can't tell the configuration, could be a leaf, could be a curtain, but what is certain that it is damn quick and only used for the readout at the end of the exposure. I'd call any mechanical mechanism designed to blind the sensor a shutter. Whether it is used to control the exposure, or just for readout purposes, or both, I would still call it a shutter. I can't confirm exactly if that's what you're seeing because quite simply I don't have one, but it is a common design for a shutter to be used only at the end of the exposure.

Interestingly enough the D70 (I think, ... possibly D40?) has the both configuration. The mechanical shutter works as one would expect all the way to the sync point. Beyond the sync point though the shutter opens before the CCD is activated, the CCD exposure is then terminated, followed by the curtain closing, and readout occurring. This allows a flash to sync with the camera up to the max shutter speed, 1/4000th of a second.
 
To clarify. What I mean is that a camera with a CCD sensor does not strictly need a shutter or mechanism that allows readout to occur in the dark. It's a nice to have feature for the image improvements but it's not critical to create a functioning camera.

The misnomer is just that the very first camera example I gave was one which didn't have a shutter, so I can't just pick up "a" P&S camera to see what you're talking about, I'd need to pick up one with a shutter. :lol:, anyway kind of a moot point so late in the thread.

My dad's C-730 had something as you described. In this case it looks to be behind the aperture blades. I can't tell the configuration, could be a leaf, could be a curtain, but what is certain that it is damn quick and only used for the readout at the end of the exposure. I'd call any mechanical mechanism designed to blind the sensor a shutter. Whether it is used to control the exposure, or just for readout purposes, or both, I would still call it a shutter. I can't confirm exactly if that's what you're seeing because quite simply I don't have one, but it is a common design for a shutter to be used only at the end of the exposure.

Interestingly enough the D70 (I think, ... possibly D40?) has the both configuration. The mechanical shutter works as one would expect all the way to the sync point. Beyond the sync point though the shutter opens before the CCD is activated, the CCD exposure is then terminated, followed by the curtain closing, and readout occurring. This allows a flash to sync with the camera up to the max shutter speed, 1/4000th of a second.

I see what you mean with "misnomer" now:)

I have 2 same style P&S cameras and I will see if I can make a video of what I see. If I can, I will post it here so we can all see what I actually saw:)

As for your last paragraph, I knew Nikon did this on few of its cameras but I didn't know this was done with CCD sensors. Especially, I didn't know D40 had CCD in it. I checked and it is true. Not only D40 but also D60 and D3000 have CCD sensors in them... Very interesting!..
Do you think that Nikon did this to provide faster sync for faster shutter speeds? Could it not be done with a CMOS sensor?
 
Last I checked CMOS sensors could not be electronically controlled with such precision (but this was about 2 years ago much could have changed since), just another reason why they weren't used widely in the research arena. All CMOS cameras I've come across have had true mechanical shutters.

Actually a lot cameras have CCDs. The CCD was always the king of low noise and high quality although the camera industry thinks exactly the opposite. Getting the most out of a CCD was hard. The device was incredibly simple and needed a lot of very carefully designed components. In small consumer and even professional cameras this integration was hard fitting in the size constraints. The CMOS on the other hand was an integrated package and made it easier to get a low noise, sufficient quality design at a reasonable cost and footprint. I'm actually surprised you still see CCDs at all in DSLRs, but certainly the wide move to CMOS is something that Nikon only did last year (maybe before) and Canon did a few years ago. The D200, D100, D2x, 1DMkI were all CCD based cameras.

Nikon didn't do this provide faster sync. You actually need to trick the camera into thinking there is no flash attached on the D40 D50 and D70 in order to get this to work which is disappointing to say the least since you lose TTL abilities with the flash. The reason for this is that high speed shutters are expensive, and unreliable. The faster the shutter the more carefully it needs to be engineered to survive. Using the electronic shutter system in cheap entry level cameras allows the flexibility to get a 1/4000th shutter speed, even if the mechanical shutter is only capable of moving at 1/250th. The high speed sync is just a bonus.


Sidenote: In our optics lab at uni 3 years ago we had a CCD which was essentially noise free and incredibly linear. Around the time where people were outright bagging Nikon for bad noise and not switching to the "surperior" CMOS. The downside is this CCD cost $15000, had a huge peltier, heatsink, and forced air cooling to ensure the sensor stays at exactly 10 degrees while running. It had a "cool down period" of 5 minutes from turning on to when it was actually usable. Was only about 1mplx too, and the size of a webcam sensor :(
 

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