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02-27-2010, 02:09 PM   #1
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difference between flash compentsation and regular EV compensation?

What is the difference between inputing exposure compensation on the flash setup screen versus via the +/- EV compensation on the K-7. does the former alter the brightness of the flash whereas the later alter apeture/shutter/sensitivity? Other? Manual didn't specify. Tx.

02-27-2010, 04:43 PM   #2
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You got it.
02-27-2010, 05:35 PM   #3
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Yep, and both ultimately alter exposure in the same way, but EV comp will still have to influence flash output in Av or X-sync modes with fixed ISOs since there is no room for altering the exposure triad settings.
03-02-2010, 07:59 AM   #4
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QuoteOriginally posted by Ash Quote
EV comp will still have to influence flash output in Av or X-sync modes with fixed ISOs since there is no room for altering the exposure triad settings.
This doesn't make sense. In Av mode, the camera will meter as if no flash is used. EC will affect the shutter speed. FEC will adjust the flash output. What does "no room for altering the exposure triad settings" mean? In Av mode, how is there no room to alter the shutter speed? Am I missing something?

03-02-2010, 11:28 PM   #5
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This is what I mean:

Set the flash on your camera- any P-TTL flash will do. Switch it on. Set Av mode on the camera. Whatever lens is on the camera, the camera will select a shutter speed of approximately 1/FL and stay there for that FL.

e.g. with a 16-50 fitted and the camera set to Av mode, the Tv is set (by the camera) at 1/60 at 50mm, 1/40 at around 30mm and 1/30 at 16mm, regardless of EV comp - so EV comp does NOT alter shutter speed in this setting, and as such the only way to increase or decrease exposure is to alter flash output.
03-03-2010, 05:52 AM   #6
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QuoteOriginally posted by Ash Quote
This is what I mean:

Set the flash on your camera- any P-TTL flash will do. Switch it on. Set Av mode on the camera. Whatever lens is on the camera, the camera will select a shutter speed of approximately 1/FL and stay there for that FL.

e.g. with a 16-50 fitted and the camera set to Av mode, the Tv is set (by the camera) at 1/60 at 50mm, 1/40 at around 30mm and 1/30 at 16mm, regardless of EV comp - so EV comp does NOT alter shutter speed in this setting, and as such the only way to increase or decrease exposure is to alter flash output.
aha, so Pentax works differently than my stuff. I thought that my K10D worked like my Canon, in that in Av it sets the shutter speed for the ambient light ONLY and does NOT take into account the flash being used. Perhaps they changed it?

I like how Canon does it, so I can quickly go to "fill-flash" mode when I'm outside, I want a good "general" exposure for the scene, but I want the flash to fill in. Av mode the way you describe it would most likely blow out any shots outside.

I've used this method for outdoors wide-open shots and got decent pictures at f/2, 1/8000s with the flash Of course the range is pretty limited when using HSS, but it's doable. If I was using Pentax, the shutter would have gone to 1/80 and the entire scene would be white.
03-03-2010, 11:32 PM   #7
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Sure, HSS is where Pentax steps in to fully automate fill flash. So if HSS is set on the flash, then in Av mode, the camera exposes for the background (using the shutter speed appropriate for the aperture and ISO selected) and fires the flash to adequately expose the foreground subject. No different there, but if HSS is not set, then the shutter speed is fixed between 1/FL (to limit camera shake) and 1/180 (camera's flash-sync speed) depending on the Av, ISO and ambient lighting combination.
03-04-2010, 05:44 AM   #8
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QuoteOriginally posted by Ash Quote
Sure, HSS is where Pentax steps in to fully automate fill flash. So if HSS is set on the flash, then in Av mode, the camera exposes for the background (using the shutter speed appropriate for the aperture and ISO selected) and fires the flash to adequately expose the foreground subject. No different there, but if HSS is not set, then the shutter speed is fixed between 1/FL (to limit camera shake) and 1/180 (camera's flash-sync speed) depending on the Av, ISO and ambient lighting combination.

Ah! That's neat...I believe Nikon has something similar to let you quickly change the behavior of Av when using flash.

I do try to keep up with Pentax, because I think it's a very unique system. Thanks for "filling" me in...

03-05-2010, 08:26 PM   #9
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No worries mate.
I've known no better being with Pentax all the way, but I'm sure both Canon & Nikon have more elaborate flash systems and customisation. I'm happy nonetheless - I know Pentax and it's worked well for me thus far.
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