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01-04-2010, 06:49 AM   #16
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To my knowledge the only shutter system that can do 1/500 with sync is a diaphram shutter in the lens, not a focal plane shutter. This is because it is the only shutter which is fully open even at maximum speed. Focal plane shutters achieve the higher shutter speed (beyond normal sync speed) by having a moving slit across the sensor, the speed of the movement and the dimensions of the slit determine the effective shutter speed, but there is no one time where above 1/180 (for pentax ) where the entire sensor is exposed at any one instant.

However, if you can gaurantee the duration of the flash to be longer than the sweep of the shutter blades, then you can have sync all the way to 1/8000 assuming you can trigger the flash as the shutter starts moving. The point is, the flash has to begin with the initial movement of the blades and there is no output for this on the camera.

As far as SLRs are concerned, to my knowledge, there is no camera out there which has higher than 1/250th sync and as others have commented, this is not a big issue as it is about 1/2 stop

Again, if you want hygh speed sync, and pentax is just like everyone else in this respect, it is done with the external flashes which can strobe the subject multiple times as the shutter moves.

01-04-2010, 08:25 AM   #17
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QuoteOriginally posted by Peter Zack Quote
1)

The highest "true" Sync speed available today is 1/250th.
Just a minor point here Peter. My 1DmkIII will x-sync at 1/300 with Canon EX flashes - but 1/250 with any other strobe. This is indeed THE fastest sync speed available on an SLR camera. And of course it is certainly not enough to black out the sun. This is too bad because did you know my Canon Speedlights ARE twice as bright as the sun?
01-04-2010, 08:28 AM   #18
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My lowly D40 will sync at 1/500, albeit with an electronic shutter.

Which begs the question, why are we still using mechanical shutters in DSLRs? Are they still necessary? Why can't we just tell the sensor to start capturing and tell it to stop 1/500th of a second later? Don't really know much about the mechanics.
01-04-2010, 08:51 AM   #19
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QuoteOriginally posted by brofkand Quote
Which begs the question, why are we still using mechanical shutters in DSLRs? Are they still necessary? Why can't we just tell the sensor to start capturing and tell it to stop 1/500th of a second later? Don't really know much about the mechanics.
At this point in time ? Mechanical shutters allow a simpler and lower cost sensor.
They don't need to design in the circuitry to turn on/off each pixel and store the captured value.
The line is getting blurred, though. A dSLR with video mode definitely has an electronic shutter build in.

01-04-2010, 12:17 PM   #20
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one additional thing to keep in mind, as people demand higher and higher sync speeds,

even if it is or will be possible with an electronic shutter, at some point, the duration of the flash will become an issue.

Full power at higher sync speeds will require much brighter and much shorter flash which will impact the flash circuitry and flash tube design and life.

you may also reach a point where although short, the intensity could be an issue
01-04-2010, 11:55 PM   #21
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Besides my k200d and my new K-7 I have a Nikon D40 because I can sync at any speed and outpower the sun. Here are some examples with only 1/4 power hot-shoe flash.
a:
1/3200 sec , off-camera flash 1/4 power camera left, 1/2 CTO gel


b:
1/4 power camera left with 1/4 CTO gel. 1/1000 sec, f5.6. Flash unit placed in "portrait" mode/vertical.
01-05-2010, 04:37 AM   #22
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QuoteOriginally posted by kunik Quote
No camera has a sync speed of 1/500... And you can't make a photo at noon look light sunset... And the amount of flash power you need to black out the sun is considerably more than can be achieved with a shoe-mounted flash
Mike may say that's not true.

https://www.pentaxforums.com/forums/868166-post2.html

And the Nikon D40 had a 1/500 sync speed (electronic shutter).

Last edited by Jodokast96; 01-05-2010 at 04:42 AM.
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