iTTL Question

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ukranger

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This has been annoying me for a while now, so if I use manual flash I get the options of full, half, 1/8, 1,16 etc. So my question is, when I use iTTL does this chose the closest option to the above or does the camera let it pick the exact exposure needed? (say something in between the manual options I have)

:shrug:

Thanks in advance
Rob
 
I believe it depends on the mode you have the camera in.....

Can't vouch for Nikons but I know with Canons, if you shoot in M the power of the flash will be altered to make sure the exposure is correct so if you are using settings that are seriously under exposing the scene, the flash will use a lot of power to compensate.

If you're shooting in Tv/Av the flash only works on a "fill in" basis rather than trying to correct the exposure.
 
Russ77 said:
I believe it depends on the mode you have the camera in.....

Can't vouch for Nikons but I know with Canons, if you shoot in M the power of the flash will be altered to make sure the exposure is correct so if you are using settings that are seriously under exposing the scene, the flash will use a lot of power to compensate.

If you're shooting in Tv/Av the flash only works on a "fill in" basis rather than trying to correct the exposure.
Click to expand...

The OP meant M as manual flash not the manual camera setting and is asking what does the flash output in auto mode, Which Phil replied too.

To expand a little when the flash is in iTTL (NIKON) or ETTL (CANON) it fires and the camera meters for amount needed and send message to the flashgun to shut off the power, The amount or setting used is any where within the output range of the flash so it can and will fall between the manual setting when required. Hope that sounds rite
 
mark2002 said:
The OP meant M as manual flash not the manual camera setting and is asking what does the flash output in auto mode, Which Phil replied too.

To expand a little when the flash is in iTTL (NIKON) or ETTL (CANON) it fires and the camera meters for amount needed and send message to the flashgun to shut off the power, The amount or setting used is any where within the output range of the flash so it can and will fall between the manual setting when required. Hope that sounds rite
Click to expand...

The OP made a reference to using manual flash but then questioned how that translates to using iTTL, i.e. what power the camera sets the flash to when using iTTL.

Whilst your answer is correct, the power the flash fires at will also depend on the mode the camera is in as per my reply.
 
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ukranger said:
Which Phil?
Click to expand...

The correct exposure, within the bounds of its power, and what it's measuring. I don't know exactly how the Nikons measure flash but you'll have a choice of flash metering pattern etc.
 
Ummm, thanks for all your answers. A bit more complex than I first thought. :-D
 
ukranger said:
Ummm, thanks for all your answers. A bit more complex than I first thought. :-D
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It's fairly simple, just have a practice with ittl, it'll get it right* most of the time, and you'll learn what makes it fail, and where it'll fails you dial in FEC.

* there's no such thing as 'correct' exposure, you might decide that the flash consistently underexposed by half a stop, or overexposed by 2/3. That's subjective.
 
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