Flash and skin tones question

[hus]

Hi all, l have a problem which l can't seem to work out. Other day l went down to take a few shots of my sons judo class.
My camera is a Canon 30D with a Canon flash 390EX, The lens I used my tamron 70-200 f2.8, First l used shutter mode then switched to AV mode and set it on f4.0 so as to get away from the f2.8 softness issue. Some of my pictures turned out great but the other half had skintones really warm, i.e. red faces, seemed under exposed. I had dialed in +1 flash exposure compensation so the white suits didn't fool the metering (I had it on partial mode) as spot metering I assumed would make the shots under exposed due to the reflection off their suits. shutter was 1/250th ISO was set at 100, so as get away from any noise issue.
The above formula I assed would have given me decent results but only half my shots were decent the other half had to be ligthened up through photopaint.
Any suggestions or ideas where l went wrong?

[R1titan]

I'ld be shooting in Manual and bumping up the ISO a little to get faster shutter speeds in HSS.
If ur bouncing the flash perhaps the distance was too far resulting in underexposure?

[kiwi]

could be a white balance issue caused by lights

[hus]

I'ld be shooting in Manual and bumping up the ISO a little to get faster shutter speeds in HSS.
If ur bouncing the flash perhaps the distance was too far resulting in underexposure?

I bounce but as you stated it did underexpose so l used direct

[hus]

I'ld be shooting in Manual and bumping up the ISO a little to get faster shutter speeds in HSS.
If ur bouncing the flash perhaps the distance was too far resulting in underexposure?

could be a white balance issue caused by lights

I selected my WB to flash.
This is why it's cornered me, l thought l had all my bases covered.

[Allann]

Any chance you can post a couple of images? One that worked and one that didn't, otherwise well just be guessing.

My guess, due to it bring in av, even though you used partial metering, the camera was still getting confused. Partial metering is still weighted to the center.


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[kiwi]

could be a white balance issue caused by lights

I selected my WB to flash.
This is why it's cornered me, l thought l had all my bases covered.

That's all very well where the ambient light is being overpowered by the flash, based on the settings you describe this appears unlikely

Check the histograms and yeah, posh some examples

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[hus]

Sorry for late reply had to do the parents taxi service for everyone in the house





here are the 2 samples the first was fine and the seceond this happened, the distance are the same and all the settings weren't changed.
Is this because I am not using the correct metering or is it something else that I am not aware of ?

[Chilli]

The exif data on both pics from what i can read is the same, I am curious for an answer from someone too !

[kiwi]

I'm going to guess here that your flash worked on 1 and dramatically less on 2 - this could be a recycle time issue, bad batteries etc


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[hus]

I had changed the flash setting on the camera to average which tells the camera the main light source is from the flash and not to be used as fill in flash. I had recharged the battries the night before.
This has really stumped me, next I get the chance I and going to use my sons cheap chinese flash to see if l get the same results.

[kiwi]

I had changed the flash setting on the camera to average which tells the camera the main light source is from the flash and not to be used as fill in flash. I had recharged the battries the night before.
This has really stumped me, next I get the chance I and going to use my sons cheap chinese flash to see if l get the same results.

Were you shooting in bursts ?

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[hus]

They were single shots and pilot light was on, only a couple of times l got carried away and attempted to do quick shots but the flash didn't fire due to it charging up.

[hus]

Hmmmm maybe time to get another flash.

[TEITZY]

Not sure if the flash uses pattern metering (full scene) the same as the camera or centre weighted but it appears in the first shot it has exposed for the blue (hence the blown whites), while in the second image it is exposing for the white, hence the underexposure.

Not that this helps, but Nikons flash metering would be much more accurate under these conditions

Would have been better just to switch everything to manual under these conditions.

Cheers
Leigh

[hus]

What is the ideal metering mode for circumstances like these.
Going full manual crossed my mind but I chickened out last minute.
But even if l went manual I would have selected 1/250th shutter and f4.0, most likely l would have selected partial metering, could it be that I am selecting the wrong metering mode ?

[kiwi]

I'd have shot manual


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[hus]

Next time will do, can't get any worse then those results.

[Wayne]

Not sure how Canon metering works, but if similar to Nikon, I think Teitzy has it. Can you see the focus points in these images?

If Teitzy is right then the camera may meter for the focus point in both spot and matrix metering, where in a Nikon, the same applies so you can try centre weighted metering which ignores the focus point and uses the central part of the frame to meter, which with the contrast in this case should have helped.

[DesmondD]

Sorry for late reply had to do the parents taxi service for everyone in the house
here are the 2 samples the first was fine and the seceond this happened, the distance are the same and all the settings weren't changed.
Is this because I am not using the correct metering or is it something else that I am not aware of ?

One thing to remember before worrying too much about your settings and the differences between the two images is that the flash could have been taking a while to re-charge which could be what caused the under-exposure , especially at a distance and at iso 100 .
Also , it's not a wb issue , that's just the under-exposure causing the colour difference .
With regard to staying at iso 100 to reduce noise , quite interestingly it could also introduce noise that way if there is under-exposure . I did a blog on exposing to the right since this comes up quite often .
Shooting at iso 400 would have made life much easier for your flash since it would only have to work 1/4 as hard and the slight bit of extra noise would be negated by the fact that you would almost always have enough flash power to light your subject .

If Canon flash is anything like the Nikon system then when you use spot metering it still resorts to a larger centre weighted pattern .
If in fact you can spot meter flash with Canon then that would definitely explain why the image goes dark when something white enters the very centre of the frame .
Quite frankly I think the problem was more likely the time it takes for the flash to re-charge between shots .
I also did a blog on beginners flash info if interested .