Struggling with flash, advice please!

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Duncan.F

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Duncan
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Hi,
Went out to an evening do with the aim of taking loads of 'people' shots for a friends album. Using a 400D/380ex flash/ Sigma 17-70.
A great many shots were comng out too dark but some were quite good and can't figure out why. Had the camera set to 'P' mode, camera always seem to be 1/60 4.5. New batteries in everything before I went!
Switched the camera to full auto, green oblong, [oh the shame] in desperation and that improved matters considerably.
Thoughts/ideas much appreciated!

Cheers,

Dunc
 
Can't write too much as I'm at work. Try manual, set ambient exposure to -1 or -2, whatever looks better. If you're using ETTL on your flash see how it looks. Otherwise just have a play in manual mode until you get the exposure you're after. Take a tripod. Consider using off camera flash with an umbrella & a light stand. Read strobist for more info.

EDIT: If you don't want to go off camera (it can often be quite inconvenient) then try bouncing off a wall or ceiling. It'll make the light a lot softer. Look for white walls and ceilings though.
 
Hey Dunk,

Without seeing the shots and the exif to see whats going on with the shots it's obviously a bit hard to comment on what to do.

I can say though that in my experience flash stuff tends to work best one of two ways. Either you make ALL the decisions and have the whole lot on manual so neither the camera or flash can start to adjust anything for you.

Or, leave it all to the camera and flash with auto set everywhere it can be. Teamwork just doesn't seem to cut it for these conditions.

Personally, I'd have no qualms about using green square mode if it got me the shots I wanted. Although I'd probably end up with '"P" mode so I can get RAW files (and maybe dial in a teeny bit of adjustment just because I'd think I know better). ;)
 
I agree entirely with Daz here. Modern flash guns are wonders of technology, but they're the thing which people seem to have the most trouble understanding.

There's two ways to go - either get a good understanding of how flash works - and put up with the headache it brings on, or let the camera do it all - in most cases it will produce more than acceptable results.

I'm a bit surprised that 'P' mode didn't always produce the results for you, it would be my choice if I wanted to rely on the camera and flash completely, but if the old green square produces the results, then use it. ;)
 
Check your options in the menu system. I don't know if it is the same for Canon as it is for Nikon but when in P or A modes it will use the flash/shutter speeds set in the menu. The default is usually 1/60 unless you over ride it.
 
One thing that most people forget is the ISO. The further away it is the stronger flash or the higher the ISO.

Most times I end up cranking the ISO to 400 or 800
Going from ISO100 to ISO400 doubles the flash range..
 
When the camera is set to P and it detects a flash, it will default to around 1/60 and keep the lens wide open. It's then upto the flash to control the exposure , using its onborad sensor.

Now if the flash doesn't have enough power you should see a warning in the viewfinder. Don't know about the 400, but my 5D will flash the flash symbol.

Large rooms and dark rooms have a serious effect on the range a flash will work, smaller lighter rooms will reflect light onto the subject, helping with the exposure.

Check the preview screen on the back of the camera, and not just the image use the histogram to determine if you have exposed correctly. If all the data is to the left then you've got an underexposure problem.
 
You are doing nothing wrong this problem has been around since Canon went digital. I talk from experience as in the old days of film the flash exposure system was far better and more reliable.This is a problem which they have now sorted as all the latest cameras have a new Digic 3 processor which has solved the problem. You can now set P and ETTL on flash and every shot is spot on.
The new 450d,40d and eos 1D have the new processor. So you either change body or the other option which i found best on the 400d is to use a Metz undedicated 54MZ4i on auto and the flash has its own light sensor built in which does a better job than canon's system. then you set your camera to manual and dial in the apperture on the flash and you will get consistant results. Rather naughty from canon because if you contact them the just tell you that you are not metering correctly and point you to there £175 flash course. They never had a flash photography course before digital ??

Hope this helps
 
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