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02-16-2013, 07:04 AM   #1
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Using K 30 onboard flash for fill flash

Has anybody tried using the onboard flash as a fill flash? I used it once a month or so ago and seemed to work fine but when I took that shot I was in scene mode "surf and snow". Yesterday I was out and tried a few shots with the built in flash for fill flash while in aperature mode and they were all several stops over exposed. When I looked at the exifs every time the main difference when using the flash versus not using it was that the ISO when using it was either 400 or 800 versus 100 when the flash was not activated. The only other difference was shutter speed with flash dropped to 1/180 (max sync speed) versus 1/250. Really don't understand why the ISO jumped up so much.

Any thoughts? Seems strange.

02-16-2013, 07:31 AM   #2
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Not that I've used the popup much as the main flash, but. my take on it is........

The K-30 flash's 'intelligence' seems to be to aim to blend in as much ambient light as possible. Auto ISO only makes this behaviour the more so as the camera can make more use of ambient light at high ISO. If the flash can't be throttled down low enough (there will be a limit) then with high ISO overexposure is a risk. It's best to keep ISO fixed and low if you want the flash to be the main lighting and well controlled.
02-16-2013, 09:40 AM   #3
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Try again with fix ISO, there are some very strange behavior concerning this with other models (bumping up the iso with no reason when using flash).
Using fixed ISO often makes the flash far more reliable.
02-16-2013, 10:49 AM   #4
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QuoteOriginally posted by SteveB Quote
Not that I've used the popup much as the main flash, but. my take on it is........

The K-30 flash's 'intelligence' seems to be to aim to blend in as much ambient light as possible. Auto ISO only makes this behaviour the more so as the camera can make more use of ambient light at high ISO. If the flash can't be throttled down low enough (there will be a limit) then with high ISO overexposure is a risk. It's best to keep ISO fixed and low if you want the flash to be the main lighting and well controlled.
I hear you. I usually don't use the pop-up flash either but didn't expect to need my flash and was trying to lighten the bag so left my Metz at home. The time before when I used pop-up for fill flash conditions were very similar and it did not bump up the ISO at all just dropped the shutter speed to be at 1/180 max. I am wondering if I should also set for high speed sync so that shutter speed is not throttled to a max of 1/180. Will try both with combinations first chance I get.
I certainly perfer to keep the ISO low. Perhaps the snow and surf mode sets ISO as opposed to auto . . .I can't find anywhere what the settings are for the different scene modes . . .would be nice to know.
Thanks,

Bob

02-16-2013, 10:53 AM   #5
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QuoteOriginally posted by Anvh Quote
Try again with fix ISO, there are some very strange behavior concerning this with other models (bumping up the iso with no reason when using flash).
Using fixed ISO often makes the flash far more reliable.
Thanks for the feedback. I will try setting Iso and also try high speed sync and see what happens.
02-16-2013, 02:47 PM   #6
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QuoteOriginally posted by bcorson Quote
I hear you. I usually don't use the pop-up flash either but didn't expect to need my flash and was trying to lighten the bag so left my Metz at home. The time before when I used pop-up for fill flash conditions were very similar and it did not bump up the ISO at all just dropped the shutter speed to be at 1/180 max. I am wondering if I should also set for high speed sync so that shutter speed is not throttled to a max of 1/180. Will try both with combinations first chance I get.
I certainly perfer to keep the ISO low. Perhaps the snow and surf mode sets ISO as opposed to auto . . .I can't find anywhere what the settings are for the different scene modes . . .would be nice to know.
Thanks,

Bob
High speed sync only works with a Pentax external flash (probably only the 360 and 540).
02-16-2013, 03:08 PM   #7
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QuoteOriginally posted by IchabodCrane Quote
High speed sync only works with a Pentax external flash (probably only the 360 and 540).
Yup I knew that too1 But it also works with my Metz 53 AF-1
02-17-2013, 03:01 AM   #8
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QuoteOriginally posted by Anvh Quote
Try again with fix ISO, there are some very strange behavior concerning this with other models (bumping up the iso with no reason when using flash).
Using fixed ISO often makes the flash far more reliable.
I agree with Anvh, on all my bodies using either built in or Metz 48 or Metz cl45 digital using any thing other than fixed iso is courting disaster!

That's fine if you can reshoot but mostly you can't so stay on the lowest iso you have.

There's a good reason for using a low one because if the flash is not filling enough and you can't or don't want to alter aperture then MANUALY increasing the iso will increase the flash output.

02-17-2013, 08:08 AM   #9
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QuoteOriginally posted by adwb Quote
I agree with Anvh, on all my bodies using either built in or Metz 48 or Metz cl45 digital using any thing other than fixed iso is courting disaster!

That's fine if you can reshoot but mostly you can't so stay on the lowest iso you have.

There's a good reason for using a low one because if the flash is not filling enough and you can't or don't want to alter aperture then MANUALY increasing the iso will increase the flash output.
I will do that in future. I gather it is not consistent as this is the first time I saw this problem using either on board flash or the Metz flash.

Also I don't understand the comment about increasing the ISO will increase flash output. With higher ISO setting you should need less light reaching the sensor.
02-17-2013, 12:11 PM   #10
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QuoteOriginally posted by bcorson Quote

Also I don't understand the comment about increasing the ISO will increase flash output. With higher ISO setting you should need less light reaching the sensor.
Sorry should have said in manual camera mode

Try changing the iso and look at the distance on the flash screen

Might not be correct to say increase the flash out put but it is the actual effect however.
02-17-2013, 02:38 PM   #11
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QuoteOriginally posted by bcorson Quote
Also I don't understand the comment about increasing the ISO will increase flash output. With higher ISO setting you should need less light reaching the sensor.
ISO is simply the sensativity of the sensor.
that means when you go from ISO100 to 200 that all the light of the image will increase by a factor of 2, that also includes the amount of flash light in the image.

So your flash power will double in effectiveness so to say in terms of light output.
02-17-2013, 07:59 PM   #12
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QuoteOriginally posted by Anvh Quote
ISO is simply the sensativity of the sensor.
that means when you go from ISO100 to 200 that all the light of the image will increase by a factor of 2, that also includes the amount of flash light in the image.

So your flash power will double in effectiveness so to say in terms of light output.
I understand ISO. What I don`t understand is the comment:
``There's a good reason for using a low one because if the flash is not filling enough and you can't or don't want to alter aperture then MANUALY increasing the iso will increase the flash output.``

Yes ISO 200 indicates twice the sensitivity to light of ISO 100 but changing the ISO to 200 does not increase the light output from the flash, in fact it would require half the light output of the flash at 200 ISO that it took at 100 ISO to get the same result. If you want to get more output from the flash for a given scene for fill flash purposes then increase the flash output not the ISO. Remember you don`t want double the exposure for the entire frame just more `fill`.
02-18-2013, 04:06 PM   #13
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Preciesly.
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