Why does the 1D use a mechanical shutter?

[Scott Larson]

It's because my quote from Chuck was in response to Daniel
Lauring's question.

Actually Chuck's quote was in response to my question over at robgalbraith.com about why my 1D's "electronic" shutter makes so much noise.

 

[Lin Evans]

It's because my quote from Chuck was in response to Daniel
Lauring's question.

Actually Chuck's quote was in response to my question over at
robgalbraith.com about why my 1D's "electronic" shutter makes so
much noise.

Indeed it was, and it was only one of your several question (four as I remember) and the one which Chuck answered that bears most directly on the apparent confusion about the action of the shutter on the 1D. Ron had posted a link to a Canon technical paper which provided the identical information, but Danny may not have read it. It's a very long thread with several side issues being discussed - I thought that Chucks explanation to your query made an easier read than ferreting out the relevant data from the bulletin.

The issues of shutter action on the removable lens digital SLR's are not as straight-forward as on the consumer cameras and their function is somewhat different. The sounds from bursts on the 1D are quite similar to the sounds on film cameras with motor drives, which probably adds to the confusion.

To me, one of the most salient questions concerns shutter life. Since the shutter is working much harder on the film cameras, wouldn't one expect to get considerably more images on the 1D, D60, D30, etc., before failure compared to the film counterpart? The MTBF should be the same, but since the shutter stays open during bursts, and considering the likelyhood of a sizeable number of burst uses, wouldn't the expectations be that it should last considerably longer?

Lin
--
http://204.42.233.244

 

[Forrest41926]

I recall the Nikon 9xx series could also fire at 1/800 or so with
some type of simple leaf shutter. Perhaps this is possible in
conjunction with the built in electronic shutters of the CCDs.
Perhaps it has something to do with the smaller CCDs they use. The
Oly E10 is limited to 1/640. I recall most 35mm P&S being somewhat
slower...like 1/400.

Probably the small CCD. Mine could expose up to 1/800 normally, and faster at f/8 ... the iris and shutter were the same thing, and it had less distance to travel at it's smallest aperture, so it could pull off close to another stop.

Can an electronic shutter sync with a flash?

Danny

Any SLR worth it's salt, including digital, uses a sliding
curtain...actually a pair; one leading and one trailing. This
allows them to produce the very high shutter speeds they have by
sliding a narrow slot of light across the image. Cheaper consumer
digicams uses leaf shutters. Leaf shutters are generally limited
to 1/500th of a second or slower.

My Olympus 2100's Leaf shutter could expose up to 1/1,150 sec, and
of course sync with the flash at this speed.

 

[Gordon Berg]

The readout speed can be an order of magnitude or two slower than
the electronic shutter speed, so it can still be useful to cover
the CCD during readout even if the mechanical shutter is open
longer than the electronic one.

Doesn't the fact that the 1D shoots bursts at the rate of 8 per second mean that they pump the data off chip in about 1/8 of a second? I haven't read it about this particular camera but I have read that, in general, the time to get the data off the sensor is the primary determinant in the max frame rate (short bursts). You'd expect that they'd fire the electronic shutter quite late in the 1/125 sec interval the mechanical shutter is open so that the vibrations arising from opening it would damp out. The full 1/125 second is just 6% of the presumeable 1/8 th second to perform the readout and it would seem easy to make the shutter darken the sensor for all but 1% of the readout time. So it could be quite effective in reducing smear.

 

[Erik Magnuson]

To me, one of the most salient questions concerns shutter life.
Since the shutter is working much harder on the film cameras,

Huh? Everything posted here to date says that the 1D shutter opens and closes for every shot. The quote from Chuck Westerfall says:

"The noise you hear during a continuous shooting sequence is mostly the shutter charging motor and the reflex mirror mechanism moving up and down."

But this is the same as a film camera! Most of the noise is mirror slap. Why do you think that the Leica rangefinders are so prozed for their quietness even though they also use focal plane shutters?

An "electronic" CCD shutter does not need a "charging motor". No motors at all. That motor is part of the mechanical shutter assembly.

wouldn't one expect to get considerably more images on the 1D, D60,
D30, etc., before failure compared to the film counterpart?

Secondly, if you've reads the entire thread, it looks like the D30 and D60 use a mechanical shutter for exposures.

MTBF should be the same, but since the shutter stays open during
bursts,

But it doesn't. There is no reason for it to. A mechanical shutter is not anywhere close to being the bottleneck for cycle time during high-speed shooting. (CCD read time 1st, mirror open/return 2nd, then maybe shutter cycle time.)

--
Erik
Free Windows JPEG comment editor
http://home.cfl.rr.com/maderik/edjpgcom

 

[Lin Evans]

To me, one of the most salient questions concerns shutter life.
Since the shutter is working much harder on the film cameras,

Huh? Everything posted here to date says that the 1D shutter opens
and closes for every shot. The quote from Chuck Westerfall says:

Eric,
I don't interperet it that way:

".....The maximum mechanical shutter speed is therefore 1/125th, since faster mechanical speeds would result in a moving slit exposure rather than one where both shutter curtains are fully retracted....."

If the "maximum" mechanical shutter speed is 1/125 and you shoot a burst of faster frames - say 4 shots at 1/10,000, how then is it possible that the mechanical shutter can open and close for every shot if it's limited to 1/125 as a maximum speed? This doesn't make sense to me....

Lin

 

[Lin Evans]

Eric,

Are you saying that the mechanical shutter opens, then the electronic shutter opens and closes for the duration of the actual first exposure, then the mechanical shutter closes, opens again and repeats the above cycle so that up to the entire burst of 8 or so frames are completed within the 1 second period and that the mechanical shutter has cycled eight times for the eight frames?

Lin

 

[Lin Evans]

Perhaps this mechanical shutter/electronic shutter thing works differently in some systems - for example, my 1D chatters away on bursts as does my D30 and DCS-760, but my Olympus E-100RS silently shoots 15 frames per second with absolutely no mechanical noise. I'm wondering then why it's necessary to close the mechanical shutter between shots on the 1D when it's possible, obviously to leave it open on other systems?

Lin

 

[Ron Parr]

Eric,
Are you saying that the mechanical shutter opens, then the
electronic shutter opens and closes for the duration of the actual
first exposure, then the mechanical shutter closes, opens again and
repeats the above cycle so that up to the entire burst of 8 or so
frames are completed within the 1 second period and that the
mechanical shutter has cycled eight times for the eight frames?

Yes, this is what Erik is suggesting.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
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[Ron Parr]

Perhaps this mechanical shutter/electronic shutter thing works
differently in some systems - for example, my 1D chatters away on
bursts as does my D30 and DCS-760, but my Olympus E-100RS silently
shoots 15 frames per second with absolutely no mechanical noise.
I'm wondering then why it's necessary to close the mechanical
shutter between shots on the 1D when it's possible, obviously to
leave it open on other systems?

Well, we don't know that it's necessary , but it has been hypothesized that it's done to reduce smear during readout:

http://www.dpreview.com/forums/read.asp?forum=1019&message=2610904

http://www.dpreview.com/forums/read.asp?forum=1019&message=2610919

http://www.dpreview.com/forums/read.asp?forum=1019&message=2614728

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

 

[Lin Evans]

Well, we don't know that it's necessary , but it has been
hypothesized that it's done to reduce smear during readout:

http://www.dpreview.com/forums/read.asp?forum=1019&message=2610904

http://www.dpreview.com/forums/read.asp?forum=1019&message=2610919

http://www.dpreview.com/forums/read.asp?forum=1019&message=2614728

I've tried to record the shutter sounds from my 1D during 1 second bursts and break it down to see if there are eight separate and distinct sounds, but so far the results are inconclusive. My gut reaction is that there are indeed eight separate sounds of shutter/mirror/motor actions for eight frames for whatever that's worth....

Best regards,

Lin

 

[shervinf]

I stand corrected. Thanks Ron!

Shervin

The 1D uses a mechanical shutter for long exposeures only.
Otherwise it is not used!

The shutter is "used" on every 1D exposure:

http://www.canon.com/camera-museum/tech/report/200112/report.html#t3

The only question is whether the fact that it's closed during
readout helps reduce smear.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/