Pages: [1]   Go Down

Author Topic: Leaf Shutter vs. Electronic Shutter  (Read 8072 times)

Kim Bentsen

  • Newbie
  • *
  • Offline Offline
  • Posts: 14
Leaf Shutter vs. Electronic Shutter
« on: March 31, 2009, 05:12:42 am »


Why is there no electronic shutter in Canon CMOS cameras allowing for higher flash sync?


I am baffled by this tech question that hopefully some technical inclined people would know the answer to it.

Older cameras such as the Canon 1D could do it. So can some of Nikons current cameras, i.e. the D50.

Flash sync speeds of 1/500-1/1000 sec would be very desirable using studio flash, as it would extend the range of the flash and/or its battery capacity (by dialling down the power). I am here talking of the situation when you outdoors want to overpower the sun with at battery powered studio flash system. High Speed sync is not an option with studio flash due to design, besides the pupose is to get more flash power from it. By using faster shutter speeds you can reduce the amount of sunlight, if you want to underexpose the ambient sunlight by 1-1.5 stops.

Companies such as Phase One/Mamiya are about to introduce a new line of lenses for their camera just fot this purpose.

This is an old question, usually answered by that only CCD sensors can do that.

Here is my point. When new CMOS sensors can do 1080p HD video, which is using some kind of electronic shutter, why can we not have a electronic shutter for higher flash sync?
Logged

Ben Rubinstein

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1822
Leaf Shutter vs. Electronic Shutter
« Reply #1 on: March 31, 2009, 10:10:23 am »

The 1D and D50 are/were CCD sensors.
Logged

BJL

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 6600
Leaf Shutter vs. Electronic Shutter
« Reply #2 on: March 31, 2009, 10:27:51 am »

Video modes use a rolling electronic shutter, reading one line at a time in rapid succession rather than recording the whole scene simultaneously. Also, the DSLR video frame rates are lower than normal flash sync speeds. So that is probably not good for freezing motion in still images.

For whatever reason, Interline CCD's are the only type so far that can electronically "freeze" the exposure over the whole sensor simultaneously. (The Full Frame type of CCD used in DMF does not seem to have this ability either.)
« Last Edit: March 31, 2009, 10:29:16 am by BJL »
Logged

Wayne Fox

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 4237
    • waynefox.com
Leaf Shutter vs. Electronic Shutter
« Reply #3 on: March 31, 2009, 02:48:27 pm »

Quote from: Kim Bentsen

Why is there no electronic shutter in Canon CMOS cameras allowing for higher flash sync?


I am baffled by this tech question that hopefully some technical inclined people would know the answer to it.

Older cameras such as the Canon 1D could do it. So can some of Nikons current cameras, i.e. the D50.

Flash sync speeds of 1/500-1/1000 sec would be very desirable using studio flash, as it would extend the range of the flash and/or its battery capacity (by dialling down the power). I am here talking of the situation when you outdoors want to overpower the sun with at battery powered studio flash system. High Speed sync is not an option with studio flash due to design, besides the pupose is to get more flash power from it. By using faster shutter speeds you can reduce the amount of sunlight, if you want to underexpose the ambient sunlight by 1-1.5 stops.

Companies such as Phase One/Mamiya are about to introduce a new line of lenses for their camera just fot this purpose.

This is an old question, usually answered by that only CCD sensors can do that.

Here is my point. When new CMOS sensors can do 1080p HD video, which is using some kind of electronic shutter, why can we not have a electronic shutter for higher flash sync?

High sync speeds are pretty easy with leaf shutters contained within the lens.  Much more difficult with Focal plane shutters, which traditionally achieved higher shutter speeds by using a "slit" that moved across the film plane.  Obviously this doesn't work with flash since the flash duration itself is rarely slower than 1/500th and is typically much faster ... 1/10,000th of a second.  So you end up with a slit.

But interestingly enough to your point, the shutter in the new canons is electronic.  This can be verified by examining the action of the shutter along with the statement by Canon that the 1st "curtain" is electronic.  Indeed there is no physical first curtain.  Without a physical 1st curtain, I"m not sure what purpose the second curtain serves.  But as evidence that the second curtain may not have anything to do with exposure time as well, note that the newer Canons CAN sync at speeds up to 1/8000th of a second with supported speedlites.

So why not other flash units?  I assume here might be some challenges ... obviously to work the flash duration must be shorter than 1/8000th of a second, and many units are slower than that ... especially studio strobes which can be as slow as 1/1000th.  No way for the camera to know.  The other problem is if you start slaving flash units most likely you can't trigger them all in such a short time.

As far as your scenario however, using fill flash and high shutter speeds to control lighting ... sounds like it is possible with the Canons.
Logged
Pages: [1]   Go Up