# Why mechanical shutter on dslr?



## Robin Usagani (Sep 27, 2011)

I was just thinking why DSLRs use mechanical shutter and are limited to shutter sync speed for flash photography.  Can't they just turn the sensor on and off to whatever shutter speed you want? I apologize if this is a stupid question.


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## Hickeydog (Sep 27, 2011)

Because the viewfinder wouldn't work, then.  That's the point of a SLR:  You see _exactly_ what the lens sees, _exactly_ when the lens sees it.


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## Bend The Light (Sep 27, 2011)

Hickeydog said:


> Because the viewfinder wouldn't work, then. That's the point of a SLR: You see _exactly_ what the lens sees, _exactly_ when the lens sees it.



But with the advent of mirrorless cameras, this is not necessary. The digital viewfinder could be made to display exactly what the sensor sees, the sensor needs to be on already to do that (whether liveview or though a digital viewfinder). You would just need something that tells the camera to start and stop recording what the sensor is already capturing.

So it already IS done...in any compact camera...


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## Big Mike (Sep 27, 2011)

Check out the Nikon D70 (and one or two other DSLR models).  It has a much higher flash sync speed because (I think) they use an 'electronic' shutter, not a a mechanical one...although, they may have a mechanical shutter as well...I'm not sure.  

One reason why (I think) electronic viewfinders are only now starting to appear on higher end cameras, is because they have always been a bit slow.  As in, they were never really 'real time' and they couldn't keep up very well.


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## Helen B (Sep 27, 2011)

Hickeydog said:


> Because the viewfinder wouldn't work, then.  That's the point of a SLR:  You see _exactly_ what the lens sees, *exactly when* the lens sees it.



My emphasis on the _exactly _when. You don't get that with live view, you get slightly old data, particularly in low light.

There are DSLRs that use an electronic shutter at speeds faster than the sync speed of the mechanical shutter.

Also remember that the shutter and mirror protect the sensor to some extent during lens changing. Battery life is lower when live view is used.

Some of these reasons apply more to the mirror than the shutter, in fairness. 

One main reason is the way in which a CCD or CMOS is read. If readout occurs in the dark, the entire image can be read at once, so motion artifacts are minimised. If the sensor is read while light is falling on it the timing may result in motion artifacts between photosite rows. Mirrors are not lightproof if they allow some light through for focus  and/or exposure, so can't be used to guarantee that the sensor is in the  dark during readout (unless the secondary mirror flipped up to close the window in the main mirror - but that would be complex).

Even when used in live view, my Nikon closes the shutter to stop live view, opens the shutter to take the exposure, then closes the shutter to read the data, then re-opens for live view. (It also waves the mirror around for no apparent reason...)

Best,
Helen


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## dakkon76 (Sep 28, 2011)

Along with what others have said, it's still probably the best way to get the image from the camera to your eye when looking through the eye piece. The only other way to do the same thing is to add yet another display to the camera - and you're still stuck with the video lag. Not to mention, you're not going to get nearly as sharp a picture as you do off of a mirror on a display that small.


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## Forkie (Sep 28, 2011)

Schwettylens said:


> I was just thinking why DSLRs use mechanical shutter and are limited to shutter sync speed for flash photography.  Can't they just turn the sensor on and off to whatever shutter speed you want? I apologize if this is a stupid question.



Isn't that just what P&S cameras do?  I thought the main problem with an electronic "sensor on/off" system was shutter lag.


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## Big Mike (Sep 28, 2011)

If you really want to sync your flash at any speed, go get something with a leaf shutter system (probably a MF camera).


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## Robin Usagani (Sep 28, 2011)

They have very smart people working for them, they can figure it out.  Theres got to be a way to make it so that you can see trough the glass without getting light leak from the view finder and being able to turn on and off sensor just like that.


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## Hickeydog (Sep 28, 2011)

And you would also look like a P&S who just bought a DSLR if you're looking at the screen instead of through the viewfinder.  

Always gotta consider how you look taking your photos, right?
/sarcasm....


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## Destin (Sep 28, 2011)

Nikon d70 is old but will give you unlimited sync speed due to it's electronic shutter


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## Robin Usagani (Sep 28, 2011)

Not familiar with Nikon.. why did they stop doing that?




Destin said:


> Nikon d70 is old but will give you unlimited sync speed due to it's electronic shutter


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## KmH (Sep 28, 2011)

The Nikon D40/D70/D70s all had electromagnetic and mechanically controlled vertical-travel focal-plane shutters.

However, mechanical shutter control was only used up to 1/250. At faster shutter speeds the image sensor is turned on/off electronically, though the flash can still be synced to the rear curtain (second curtain in Canon speak).

The feature first appeared the D1.

Flash sync at faster than 1/500 with those Nikon cameras can only be accomplished with 'dumb' speedlights.


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## Overread (Sep 28, 2011)

I've seen some custom setups (made out of computer CD trays I think or might be harddisk?) which allowed for a faster shutter for higher speed snyc; though it was for specialist use and attached to the end of the lens as a light blocker; essentially you'd shoot in bulb mode or with a slow enough shutter speed and then trip the external shutter attachment with the lights to make the exposure.


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## Tony S (Sep 28, 2011)

The original Canon 1D had that feature even though is still had a shutter (my memory is fading but I believe it was a CCD sensor before they went to CMOS), one of the best things about that camera was being able to sync at 1/500 (handy with studio strobes) and go to High-Speed sync (FP Flash) - up to 1/16,000 sec with a dedicated Canon flash.


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## Garbz (Sep 29, 2011)

Schwettylens said:


> Not familiar with Nikon.. why did they stop doing that?



There are several downsides to having an electronic shutter. One was mentioned above and that is that readout occurs across the sensor called a rolling shutter. In extreme cases this could make the results of the picture look like the slow focal plane shutters of the 60s distorting moving images. This one can be worked around through the use of a global shutter, but the last CMOS sensor I saw implementing a global shutter without sacrificing performance cost just upwards for $10k. CCDs on the other hand could very easily be read out globally as the name implies, "Charge Coupled" meaning the image is not read out from the same part which records the light. Their issue though is when the the charge is transferred and light still falls on the sensor you end up with horrendous smear or blooming. 

So in either technologies a mechanical device we have more than 60 years experience with does the trick. 



Forkie said:


> Schwettylens said:
> 
> 
> > I was just thinking why DSLRs use mechanical shutter and are limited to shutter sync speed for flash photography.  Can't they just turn the sensor on and off to whatever shutter speed you want? I apologize if this is a stupid question.
> ...



Lag is introduced on CMOS cameras. Many P&S have CCDs. The lag was just the result of outright ****ty performance. For the most part many P&S have very little actual shutter lag but were horrendously slow at powering on, focusing, readout, displaying the image, not to mention that they needed to first close the shutter and turn off liveview. Also ever notice that many P&S cameras suffered bloom in liveview but not in the final image? You'd be amazed how many of them actually had rudimentary mechanical shutters if for nothing else than to read out the data from the sensor.  See D70, D40, Canon 1D for examples of cameras which used electronic shutters but negligible lag. But see above for a reason why it's bad.



Destin said:


> Nikon d70 is old but will give you unlimited sync speed due to it's electronic shutter



Not quite unlimited. They limit it to 1/500th or 1/1000th from what I remember due to efficiency reasons. In theory the sensor can read out at a shutter speed faster than the time a flash bulb is on when fired at full power, so if you go above 1/1000th you start getting bizarre power characteristics from your flash.


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## Destin (Sep 29, 2011)

Garbz said:
			
		

> There are several downsides to having an electronic shutter. One was mentioned above and that is that readout occurs across the sensor called a rolling shutter. In extreme cases this could make the results of the picture look like the slow focal plane shutters of the 60s distorting moving images. This one can be worked around through the use of a global shutter, but the last CMOS sensor I saw implementing a global shutter without sacrificing performance cost just upwards for $10k. CCDs on the other hand could very easily be read out globally as the name implies, "Charge Coupled" meaning the image is not read out from the same part which records the light. Their issue though is when the the charge is transferred and light still falls on the sensor you end up with horrendous smear or blooming.
> 
> So in either technologies a mechanical device we have more than 60 years experience with does the trick.
> 
> ...



Unless, as mentioned, you have dumb speedlights. I use lots of manual OCF, and therefore was able to use shutter speeds up to 1/4000th of a second alot of the time with my old d70. I'm thinking about picking up another d70 (they're DIRT cheap) just to have for situations like that.


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## table1349 (Sep 29, 2011)

Electronic isn't always better.  The common electro/mechanical shutter is easy to build, easy to install, easy to adjust, easy to repair and easy to replace at a lower cost than a sensor.   Lose a electro/mechanical shutter and have it replaced you have the same sensor producing the same results.  Replace the sensor and it's rendition of color may be off from what you are used too.  

It's kind of like a car.  You tires are worn out.  Do you really need to replace the entire drive train, or just the tires?


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## Crollo (May 24, 2012)

Teribly sorry to be _that guy_ that just _has to bump that old thread_, but... Are there people seriously arguing the advantages of OVF vs EVF over the _*SHUTTER?*_ We're discussing the *SHUTTER TYPE*, not the mirror.


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## Sw1tchFX (May 24, 2012)

Because when you have electronic shutters, this happens: 









Also, unless you want to use CCD's again, CMOS sensors can't do global shutters because they read the sensor from the top-down instead of all at once like a CCD.


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## gsgary (May 24, 2012)

Schwettylens said:
			
		

> Not familiar with Nikon.. why did they stop doing that?



My 1Dmk1 will sinc at 1/500 and so will my Mamiya


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## kassad (May 24, 2012)

I can understand the arguments of ccd vs cmos, but why can't they make specialty lenses with a leaf shutter like are available in medium formats?   I would think if they offered a portrait lens with a leaf shutter option there would be enough demand to justify development.


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## Overread (May 24, 2012)

The problem might be that introducing the leaf shutter into their lenses would increase lens development, design and production costs and, as a result, drive the lens prices higher still than they already are. What with the recession hitting many of their target market and rises in prices of raw materials (to say nothing of the disaster in Japan) they might feel that further rising of the price of their lenses would not be suitable for their primary target market.


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## kassad (May 24, 2012)

Overread said:


> The problem might be that introducing the leaf shutter into their lenses would increase lens development, design and production costs and, as a result, drive the lens prices higher still than they already are. What with the recession hitting many of their target market and rises in prices of raw materials (to say nothing of the disaster in Japan) they might feel that further rising of the price of their lenses would not be suitable for their primary target market.



I hear what your saying but Canon didn't hesitate in bumping the price of the 24-70 2.8 almost $1000.   That's not even a new type of lens that's an upgrade to an existing lens.   If Mamiya can sell a 80mm 2.8 leaf shutter lens for $2500 to a tiny specialised market I would think Canon could sell and similar lens to a much larger market at either a lower price or faster aperture.   Heck they would be able to sell it with the same specs and price and it wouldn't compete with the 85mm F1.2 which is retailing for only $300 less.


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## gsgary (May 24, 2012)

Phase One with right will sinc with right lens  at 1/1600 or it cold be 1/16000 will have to check


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## Overread (May 24, 2012)

I'd think 1/1600 - 1/16000 sounds insane for a sync speed and closer to what I'd be expecting from specialist gear (of course saying that Phase One IS specialist gear - just not the kind I'd expect to see such a speed from).


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## table1349 (May 24, 2012)

kassad said:


> I can understand the arguments of ccd vs cmos, but why can't they make specialty lenses with a leaf shutter like are available in medium formats?   I would think if they offered a portrait lens with a leaf shutter option there would be enough demand to justify development.


Simple answer, they can.  Reality, no reason to reinvent the wheel.  Not enough gain for the costs.


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## gsgary (May 24, 2012)

Overread said:


> I'd think 1/1600 - 1/16000 sounds insane for a sync speed and closer to what I'd be expecting from specialist gear (of course saying that Phase One IS specialist gear - just not the kind I'd expect to see such a speed from).



Checked 1/1600


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