Fill Flash in low light situations

[alfarmer]

Hi.

 

I've read several web articles & tutorials on flash photography, but

still can't get my 580EX to do what I want in low light situations --

it seems to always over-flash.

 

It seems there's no way I can rely upon TTL logic, so I need to set

flash exposure manually. What's the best way to do this QUICKLY when

my 5D is in aperture or shutter priority mode? It usually takes me

10-30 seconds to get things adjusted and that really annoys people, so

I'd like to get faster at it and figure I may just need to learn a new

technique.

 

More importantly, I usually get too much flash and the subject gets

that unnatural look. Nice and crisp, of course, but unnatural. This

is why I tend to shoot very high ISO on fast lenses, but that doesn't

always work because there are times I'd like more DOF.

 

Anyhow, thanks in advance for the tips!

 

Regards,

ALF

[oofoto]

"I tend to shoot very high ISO on fast lenses"

This combination will give you a high shutter speed which in turn means the flash will light up your subject and your background will be dark giving that unnatural look. Try setting your ISO at 400. Move into Manual mode and set Av at 5.6 and Tv at 1/30 and see if this changes things it's very quick to do.

[mark u]

Which body are you using?

[oofoto]

That'll be the 5D Mark

[robert lee]

"I tend to shoot very high ISO on fast lenses" No, I think this is correct (at least with my non-dedicated stobes.) High ISO with the lens opened up means the least amount of flash power is necessary, allowing the maximum amount of ambient illumination to be integrated into the exposure.

 

"I usually get too much flash and the subject gets that unnatural look." Have you tried a diffuser? Here, try a simple thing first.

 

1. Point the flash head directly up.

 

2. Hold a sheet of white photocopy paper a few inches above the flash head, and angle it about 45 degress to the ground.

 

3. Take the exposure. You should find the resulting lighting much softer, and without the deer in the headlights look of direct flash.

[rodney_gold1]

You can dial in about -1/3 to -2/3rd FEC(5 secs with a 580) you should get exccellent results. I think the problem is that auto flash fill reduction will probably not operate if the light level falls too much and the camera will always assume the flash is the main source of illumination at low EV levels - if this is the case , then one needs to dial in even more negative FEC (flash exposure compensation)than 2/3rds of a stop.

[picturesque]

First, check to see that custom function 14 is not set to averaging. In this mode, with my 20D (I believe the 5D is similar), automatic flash fill is not performed and I find I get that flashy look outdoors where I only want a little fill, even when dialing down flash compensation. Canon's automatic fill flash reduction is actually very nice. I am surprised that you're getting such "flashy" results, unless you've got CF 14 set to averaging, so it is so dim that auto fill flash doesn't come into play. If you are talking about even shade with fill flash, you have to dial the fill flash down up to 2 stops sometimes to avoid the flashy look.

 

Otherwise, there is a custom function on the 580EX (forget which one) that allows you to use the dial directly to quickly control flash compensation.

 

Outside in contrasty lighting, I find aperture priority will average the light out too much, so that you get burned up highlights. I often use minus ambient compensation combined with minus to plus flash compensation, depending on the situation. I find manual mode much easier since I (not the camera) make the decision about how the background gets exposed in relation to the foreground.

[alfarmer]

Thanks for the GREAT info, everyone! I'll get another chance to experiment this weekend...

 

ALF

[awindsor]

I think I see your dilemma. If you are using a flash to illuminate the subject because light levels are "too low" it is essentially impossible to get a balanced exposure since the background is always underexposed. Most people like this look. It is artificial but makes the subject "pop". Whay you need to do is to decide how much difference between the ambient and the main subject you can stand. Typically I will let the background be underexposed by 1 stop and then use the flash to light the main subject. This often involves slow shutter speeds, especially if you are not shooting wide open. In this case I always use 2nd curtain sync since people tend to relax after the flash and so it is important to get the main flash to occur at the end. There is the annoying E-TTL preflash. Depending on the subject you can use FEL and then "prep" the subejct with a cue like "smile" or "cheese".

[digitmstr]

Set the camera to M and then, adujst FEC to taste.

[david_ceruti]

I agree with Gampi. I get the settings in Av mode, use the settings on manual (with some tweaking) and then set the flash to underexpose 2/3 stops, shoot a test shot, check the histogram and then go for it. I also used this method when shooting a rock concert but set the flash minus 1 - 3 stops and got great atmosphere from the stage lights and fog while getting nice detail on the performers

 

Good luck!