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10-19-2009, 08:00 AM   #1
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Questions about K100D Super External Flashes

Hi guys,

I finally had the chance to use the K100D Super with the AF540 and few weird things happened:
  • When on Av Mode and flash mounted on camera, the shutter would lock at 1/50s. I thought something was wrong with the camera, but as soon as I removed the flash, Av would work normally again (shutter varying as Av was selected).
  • What is the Xsync for these babies: in "M" mode, the fast i could get was 1/125 (or maybe 1/100, bad memory) but DEFINITELY less than the K10D. Is this correct?
  • Another question is regarding wireless option to control the AF540: can the K100D Super do wireless flashing or not?


Thanks in advance!

BB

10-19-2009, 09:18 AM   #2
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QuoteOriginally posted by BBear Quote
[*]When on Av Mode and flash mounted on camera, the shutter would lock at 1/50s. I thought something was wrong with the camera, but as soon as I removed the flash, Av would work normally again (shutter varying as Av was selected).
Unless I'm misunderstanding something, that's normal, even for the builtin flash. Remember, in flash photography shutter speed is largely irrelevant, since the duration of the flash is far shorter than the shutter speed anyhow. So Av mode tends to just set something like "1 / focal length" as your shutter speed, unless that would actually result in overexposure just due to the ambient light.

Sorry, I don't know anything about the AF540 in particular or wireless in general, so I can't help with your other questions.
10-19-2009, 09:30 AM   #3
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Thanks for the reply Marc,

But I found this behavior somehow different from what I was used to on the K10D.


I have to re-confirm if during Av mode, the k10D also locks the shutter at some number. The k100D was locking it at 1/50 and I was using the FA 35, maybe a coincidence? Not sure...


Also, under further investigation, it seems like the Xsync was supposed to be the same as all the other Pentax digital, at 1/180... but it is around 1/100 (or maybe 1/125). That is weird too...



Any other inputs?

Thanks

BB
10-19-2009, 07:06 PM   #4
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I am not familiar with AF540, I use a dumb flash and never had an issue with the shutter speed. Is the flash set to some sync mode perhaps?

The max sync should be 1/180. As for wireless, the built-in flash cannot trigger the af540, you need another external flash(af360 or af540) mounted on the camera or use a radio flash trigger.

10-19-2009, 07:16 PM   #5
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I suppose the K10D might use a different algorithm, but the *istDS, K100D Super, and K200D all do what I said in Av mode with flash: set shutter speed to a fixed value that depends on focal length, unless that shutter speed would result in overexposure. Meaning in most real world situations, you get the focal-length-dependent value indoors or at night, and whatever Av mode might normally produce without flash outdoors.
10-19-2009, 07:36 PM   #6
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Marc's right.
Shooting with flash on Av mode tells the camera that it will use flash but will keep the shutter speed at a hand-holdable speed to increase ambient light recording on the image. This becomes more significant in low-light situations at higher ISOs, with a more balanced lighting in a dim environment lit by the flash.
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