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09/25/2007 01:52:51 PM · #1 |
What is the advantage of a mechanical shutter over an electronic one?
While the D70 has a flash sync of 1/500 if you trigger a non-nikon speedlight or use a pocket wizard to fire a strobe then you can achieve an even higher flash "sync" up to 1/8000.
This has been speculated to be possible b/c above 1/250(?) the shutter is electronic so the actual blades may be open longer but the sensor is active for a shorter period of time.
Thread here - //photo.net/bboard/q-and-a-fetch-msg?msg_id=00I46J
So my real question is why have a mechanical shutter at all?
Why wouldn't an electronic "shutter" be better?
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09/27/2007 11:09:42 AM · #2 |
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09/27/2007 11:17:31 AM · #3 |
my guess (and just a guess)
would be there is light bleed into the sensors as the data is read out ..
there would also be light hitting the sensor before picture is taken requiring a down time / null out time to zero 'blacks' ..
this is likely one of the reasons P&S are sooo slow to respond ...
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09/27/2007 11:24:28 AM · #4 |
In real world applications there is no advantage of one over the other at the same speed. The D70 without the electronic shutter would sync at a slow 1/125. The shutter in my D200 syncs at 1/250 and is a more rugged unit that will probably we still working long after the one in my D70s has bitten the dust, but when I want to sync at high speeds without losing the power I would in FP mode on the D200 I reach for the D70s every time.
FYI I'd seldom actually use the D70s at 1/8000 unless on very low power settings as the flash duration would actually be longer than the sync causing hard to calculate exposures. Real world use usually tops out at about 1/2000, which is still much faster than 1/250. Also you can use Nikon flashes, just cover up all the contact pins except the center sync on the flash with electrical tape.
Edit to add:
Ops, I guess I ignored your "real" question. I would assume like Ralph that is due to speed and probably heat buildup in the sensor, which causes noise. It would not be for protection as the shutter is quite a bit more fragile than the sensor or more precise the filter pack in front of the sensor. I wonder if video cameras have mechanical shutters? It is usually the shutter which defines the life span of a DSLR, so maybe manufacturers want to keep them there for repeat sales?
Message edited by author 2007-09-27 11:44:19. |
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09/27/2007 01:53:40 PM · #5 |
As far as I know, electronic shutters only work with CCD sensors. The only Canon with a CCD sensor is the 1D, which also has an official 1/500th sync but can be pushed to 1/2000th. The 1D also has a top shutter speed of 1/16000th, which is the fastest that I know of. I have actually gone over 1/8000th a few times, but there's not many times I need to shoot wide open at ISO 400 in broad daylight...
Video cameras don't have mechanical shutters, and I believe they constantly vary the exposure time of each frame to compensate for the light. The range is limited though, it needs time to finish the exposure and start the next one fast enough to keep up with the framerate. And using a too fast shutter speed can actually look choppy even with 30fps, that's why most of the good ones have built in ND filters to keep the shutter in the same ballpark with brighter light. |
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09/27/2007 09:49:22 PM · #6 |
There used to be an LCD shutter used to take pictures of atomic bomb detonations, but that was a very specialized camera. :)
Some flashes have a high speed sync mode where they'll flash more than once as the shutter "window" moves. |
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