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

http://i43.tinypic.com/2poz8qq.jpg

http://i42.tinypic.com/10ehe84.jpg

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 ?:confused013

[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 :D

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 ?:confused013

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 (http://desmond-downs.blogspot.com/2010/01/exposure-and-noise-exposing-to-right.html) 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 (http://desmond-downs.blogspot.com/2010/02/flash-information-for-beginners.html) if interested .

[hus]

I also did a blog on beginners flash info (http://desmond-downs.blogspot.com/2010/02/flash-information-for-beginners.html) if interested .

DesmondD that blog is a jem, thanks for putting the effort to put it up already booked marked and will be checking on a regular basis :food04:

[DesmondD]

DesmondD that blog is a jem, thanks for putting the effort to put it up already booked marked and will be checking on a regular basis :food04:

Thanks , it makes it easier to explain things that come up regularly on the forums :)

[Chilli]

DesmondD, a huge thankyou from me also..

[DesmondD]

DesmondD, a huge thankyou from me also..

Thanks for the feedback :) It's amazing what you can learn from "springbok photography" hey ! :D

[Gluggy]

Just a thought, could the focal length of both shots change the impct of the flash? Looking at the exif data, one shot is at 50mm and the other at 70mm. Hus did you change your distance between you and the subject? If so then its an example of the light squared rule, where the further the light source is from the subject then light drops off quickly? even a few feet difference effect the light fall off on the subject. Just a thought.

[Brodie]

yeah the guys have pretty much sussed it out. When using ETTL it will often do funny things. You need to be wary of what metering mode your in and be sure to get in close to your subject to fill the frame to help it make its calculations. Too much background in the frame can cause the flash to use more power because its going to want to light the whole room.

Remember when using flash, the flash will freeze your subject so you can drop back on the shutter speed. And Id recommend bumping that ISO up a bit. Bring a bit more of the ambient light back. On the 30D you run into noise trouble at just 400 but give it a go.

[hus]

Gluggy the distance is the same, on one of the pics I used my prime and he other I used my zoom lens (thats another issue with this body).

Brodie you are right, 30D is not too great above 400 iso, so I have already started the grovelling procedure at home to allow my finance department to approve the purchase of a new Canon 50D

Thanks to everyone for their feedback on this problem.:)

[viscountvics]

Others have answered already, but i'll probably put more emphasis on desmond's answer about the flash recycle. I never used canon flashes myself, so this is guesswork.

If you are shooting consecutively at iso 100 and long distance, you are asking alot from ur flash. Even though you just charged your battery the night before, it can still do a slow recycle. These kind of shot probably can be avoided by:
1. Shooting closer (with wider lenses)
2. Bump up iso to >400
3. use battery packs
4. Go full manual

I really almost go full manual nowadays too. Its quite scary at first, but it get easier when you are used to it. Hope it helps you for next time.

[Brodie]

Others have answered already, but i'll probably put more emphasis on desmond's answer about the flash recycle. I never used canon flashes myself, so this is guesswork.

If you are shooting consecutively at iso 100 and long distance, you are asking alot from ur flash. Even though you just charged your battery the night before, it can still do a slow recycle. These kind of shot probably can be avoided by:
1. Shooting closer (with wider lenses)
2. Bump up iso to >400
3. use battery packs
4. Go full manual

I really almost go full manual nowadays too. Its quite scary at first, but it get easier when you are used to it. Hope it helps you for next time.


In this case the flash has still gone off, its just not powerful enough to overcome the settings set in the camera. ETTL does whacky things depending what it meters. beauty of manual modes.

Shooting this kind of scene the canon flash with good batteries wont have any dramas firing off like crazy. Recycle times shouldnt be a problem until you really wear out the flash after taking a stack of photos.