Camera shutters-- techincal question

[lkWinnipesaukee]

Why do digital cameras even have shutters? Can't the camera just "turn the sensor on and off?" Why the need for extra moving parts?

 

[Sw1tchFX]

protection. I would HATE to see what my sensor would look like after switching out lenses.

 

[RVsForFun]

...and no one can give me a plausible answer.

If it's just for sensor protection, a simple baffle will suffice and not have the complexity of a focal plane shutter.

Why one is needed can't be explained as you can simply tell the sensor to read (or not read) the chip when the baffle or lens is open - no need for the physical limitations of a mechanical shutter.

My Kodak P880 will sync with flash at 1/4000th of a second. No mechanical limitation whatsoever...so why does my "pro" DSLR have a mechanical shutter?

 

[The_Traveler]

My off-the-wall guess would be that turning on/off the millions of pixels can't be done simultaneously as accurately as needed for fast, precise exposures.

 

[DSLR noob]

More controlled light exposure? No sensor warmup or whatever.

 

[panocho]

heritage and continuity with the origins of photography?...
silly reply, yet...

 

[DSLR noob]

I'll bet it actually is because of the size of the sensor. It is larger than a P&S by FAR. /Since the speed of light (an image) is the same as speed of electricity (activating pixels), The entire sensor activates behind the shutter and THEN is evenly exposed.

 

[JDP]

I'll bet it actually is because of the size of the sensor. It is larger than a P&S by FAR. /Since the speed of light (an image) is the same as speed of electricity (activating pixels), The entire sensor activates behind the shutter and THEN is evenly exposed.

That's what I think too. P&S have their sensors on all the time, since they take a lot less power. If you kept the sensor of a dSLR on all the time, you'd suck through batteries real fast.

 

[RVsForFun]

A CCD/CMOS chip has no moving parts - it's GOT to be easier to read a jillion pixels than turn the whole chip on, read it continuously and use a mechanical shutter to expose the image area. I'll repeat my statement that my Kodak P880, an 8MP camera, has no mechanical shutter whatsoever. It syncs with flash all the way up to its maximum shutter speed of 1/4000th. I own professional video cameras that electronically read their image chips 30 times a second with NO shutter.

My off-the-wall guess would be that turning on/off the millions of pixels can't be done simultaneously as accurately as needed for fast, precise exposures.

 

[RVsForFun]

Electronic control has got to me more accurate than a mechanical shutter, and you'd still have to warm up the chip (if, in fact, it even needs to be warmed up) ANYWAY prior to a mechancial shutter firing, right?

More controlled light exposure? No sensor warmup or whatever.

 

[JDP]

There's also something about how the sensor has an ON time of 1/250th + - anything faster then 1/250th it will energize the sensor and use the shutter to control exposure.

 

[Flash Harry]

your cameras dont have mechanical shutters, they are electronically controlled shutters, and as we all know overexposure of our digital chips is a real bummer so we do need a mechanism to control this, it also gets us away from the "lag" of the P&S mechanism so we capture what we require and not a blank space after the happening, plus at heart, we're quite a bunch of stick in the muds so to hear the kerplop of a shutter lets us all know we now have an image on the card. Photography is about controlling light, aperture and shutters allow this. H

 

[RVsForFun]

My 20D certainly does have a mechanical shutter. I have a friend who had his mechanical shutter shutter in his digital Rebel go belly up, which resulted in over-exposed photos. His entire shutter assembly had to be replaced (which is was under warranty). Our cameras have all the issues of mechanical shutters - winding force, sync speed limitations, etc. The new 5D from Canon, for some unknown reason, actually has a slightly lower sync speed than its predecessors of 1/200th. My Kodak P880, with the same image sensor size as my 20D's, has no shutter at all as it has a continuous electronic viewfinder.

your cameras dont have mechanical shutters, they are electronically controlled shutters, and as we all know overexposure of our digital chips is a real bummer so we do need a mechanism to control this, it also gets us away from the "lag" of the P&S mechanism so we capture what we require and not a blank space after the happening, plus at heart, we're quite a bunch of stick in the muds so to hear the kerplop of a shutter lets us all know we now have an image on the card. Photography is about controlling light, aperture and shutters allow this. H

 

[lkWinnipesaukee]

My XT does as well. And I know the XTi, 20D, d40, d70, and d80 all have shutters....

So basically, every dSLR has a shutter.


*caa-lick*


Wait a minute. Since my camera is still under warranty, I can get a new shutter installed free if mine dies?

Well if it's going to die, it might as well be when under warranty, so when it expires I'll have a fresh shutter. Which means I have to take a TON of pictures!!

 

[Alex_B]

your cameras dont have mechanical shutters,

The shutter of my digital certainly is mechanical!

they are electronically controlled shutters,

and so is the shutter of my film SLR !

Still it is mechanical