photographing events in low light with on camera flash

[MrJones]

Hi all,
so I went and photographed my first "official" event this weekend.
it was held indoors and the lightning was not too bright to say the least.
I used my canon 40D, mostly with the 24-105 f/4 L lens attached to it and a 430EX flash unit on camera, mostly bouncing from the ceiling.
I've noticed many photos came out with a dark background and was wondering how can I solve it next time. is it got to do with the f/4 aperture? would f/2.8 will let in more background light when using a flash unit?
I was shooting with low shutter speed of 1/30 to let it more background light but it didn't always work.
this is an on of the worst shots as an example with f/6.3 at 1/30 with ISO 250 and an evaluative metering mode.



this is SOC photo.
I've been doing PP work on other photos to brighten up the background but I would be happy to cut that to a minimum. PP for 400-500 photos is not as fun as you might think

[inkista]

Originally Posted by MrJones

...
I used my canon 40D, mostly with the 24-105 f/4 L lens attached to it and a 430EX flash unit on camera, mostly bouncing from the ceiling.
I've noticed many photos came out with a dark background and was wondering how can I solve it next time. is it got to do with the f/4 aperture? would f/2.8 will let in more background light when using a flash unit?

Yes, f/2.8 would, but since you're shooting with the 24-105, f/4 you can't use f/2.8. You're limited to f/4.

I was shooting with low shutter speed of 1/30 to let it more background light but it didn't always work.

But it helped.

You're fighting a lot of different issues. The main one being that you don't have much light, and that a 430EX isn't that powerful AND you were bouncing for diffusion (which probably robbed you of about a stop of light at least).

this is an on of the worst shots as an example with f/6.3 at 1/30 with ISO 250 and an evaluative metering mode.

Well, you had room on the ISO. I'd say bump it up to 800 next time you're in that situation. A flash cannot light up an entire room. The background illumination is going to come from the ambient lighting. If you want more background to show up you either have to a) light it, or b) let more ambient light in via iso/aperture/shutter speed. Increasing your ISO will also be kinder to your flash's power output.

My basic advice when you start out shooting flash is that first, make sure you're really comfortable shooting in full Manual and that you know how to swap stops among iso, aperture, and shutter speed before you start messing about with flash. Because flash is just going to throw to more factors onto the exposure pile: flash power output and flash distance, as well as make you juggle the balance between the ambient and flash illumination levels. In effect, before you can learn to juggle five balls while riding a unicycle, better to know how to juggle three while standing on the ground.

I'd also recommend reading the following articles about balancing flash and ambient:

Strobist: Lighting 102: Assignment - Balance
Strobist: Lighting 102: 3.3 - Balancing Flash/Ambient Indoors

And these articles on bouncing:

Planet Neil: Tangents: so what are your settings?
Planet Neil: Tangents: directional light
Planet Neil: Tangents: my choice of flash modifiers

[MrJones]

thanks inkista.
i know I can't go lower than f/4 now, but I can always make the swap to a 24-70 f/2.8
I'll have to try the ISO next time, I didn't want to use a high ISO to avoid the noise. I guess around 600 it would still be good.
thanks again for your help.