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03-10-2015, 01:09 PM   #31
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I have checked my K-3 in TAv-Mode. After pressing "AE-L" I can change the speed while the camera chooses the ISO accordingly (not the aperture). And I can also change the aperture while the camera chooses the ISO (not the speed). In my opinion that's what you want.

At the beginning you mentioned, that your are using firmware 1.0. I'm using firmware 1.11. May be, that's the problem, but also may be, I had changed some setting month ago and I don't remember.

03-11-2015, 02:08 AM   #32
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QuoteOriginally posted by siegbert Quote
I have checked my K-3 in TAv-Mode. After pressing "AE-L" I can change the speed while the camera chooses the ISO accordingly (not the aperture). And I can also change the aperture while the camera chooses the ISO (not the speed). In my opinion that's what you want.
Steve already suggested this as well.
But there seems to be a problem with auto iso and flash. i never work with flash so i don't have a clue.
Would love to understand though...
03-11-2015, 02:25 AM   #33
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QuoteOriginally posted by siegbert Quote
I have checked my K-3 in TAv-Mode. After pressing "AE-L" I can change the speed while the camera chooses the ISO accordingly (not the aperture). And I can also change the aperture while the camera chooses the ISO (not the speed). In my opinion that's what you want.

At the beginning you mentioned, that your are using firmware 1.0. I'm using firmware 1.11. May be, that's the problem, but also may be, I had changed some setting month ago and I don't remember.
Thanks a lot for that. Oh, I guess is the Firmware then. But I guess I still need to AE lock to avoid the ISO flying around during TAv mode. But anyway, is not that important. Just need to work my fingers more. Not an issue at all.

Cheers and have a nice day ya....
03-11-2015, 04:35 AM   #34
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QuoteOriginally posted by grispie Quote
But there seems to be a problem with auto iso and flash. i never work with flash so i don't have a clue.
Would love to understand though...
Read the camera manual It has a table with guide numbers at the different ISOs. But you probably skipped that part as you don't use flash

Guide number defines the power of the flash. With a simple flash (no (p)TTL or auto-thyristor, no power settings) correct exposure of a subject at a given distance is defined by guide number and aperture. The basic formula that reflects this is

subject distance = GN / aperture.

As guide number varies with ISO, one needs to change the aperture when ISO changes if the subject distance does not change. If one forgets this, result will be underexposed or overexposed flash shots.

The same formula applies to auto-thyristor and (p)TTL flashes; however the calculated distance is now the maximum subject distance. The flash (auto-thyristor)) or the camera ((p)TTL) determine correct exposure and the flash light will be switched of when the subject is correctly exposed. When a subject is closer than the maximum distance, it will still be correctly exposed. No issues with (p)TTL and auto-iso; auto-thyristor can have a problem if aperture and ISO on the flash don't match those on the camera.

On some auto-thyristor flashes (those that don't support (p)TTL) you have to set ISO and aperture to reflect the settings on the camera; forgetting this might again result overexposed or underexposed images. Others (that support (p)TTL as well) can take / get those settings from the camera and from that perspective act like (p)TTL flashes.

There is however also a (lesser known) minimum flash distance (roughly 10% if the maximum; use this as rule of thumb if documentation does not give a number); and that is where the problems comes is. Camera cranks up the ISO and then the minimum flash distance can easily become greater than the subject distance and result is overexposure.

Hope this explains it.

Note: subject distance is the distance from flash to subject without bounce; formula changes when using bounce.

03-12-2015, 12:30 AM   #35
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QuoteOriginally posted by sterretje Quote
Hope this explains it.
yes it does!
thks for that :-)
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