A few questions about on an off camera flash.
 

I have a few questions about flash use. I have never used one so the questions might sound stupid but if you have a e-ttl flash but you are bouncing the light would you have to correct the compensation for that? And the same goes for when its of camera now the flash could be further or closer to the subject surely the e-ttl is not going to be accurate then?

I have a wedding next year and the reception is at a brand old building with very heigh roof and dark wood panelling everywhere so bouncing will be a problem. What should i do?

E-TTL should compensate for wherever the light is pointed, provided the flash is powerful enough.

ETTL means the flash sends out a pre-flash microseconds before the main flash during which the camera/flashgun measure the light and make an adjustment for the main flash before it then fires, so in theory it doesn't matter where the flash is pointed.

Thank you. That makes more sense now.

If you have high ceilings with dark panelling then you are going to have major problems with bounced flash. Can I suggest that you take an assistant with you to hold a reflector and bounce the flash off that.

I'm with Steve. Bouncing off dark panelling is useless; not only does it soak up all the light, the little you get back will be coloured. High ceilings are similarly problematic.
If you can, always have an assistant with you when you do a wedding. He can hold the reflector, help with arranging groups and it gives you someone to blame when it goes wrong;)

Thanks guys. I was looking at the mini softboxes that attach to the flash which might help. Anyone used one of them? The wedding is a friends so i will know everyone there i will just grab someone to hold the reflector at the time.

I have an interfit strobies softbox but never had the chance to use it for portraits. It is really fiddly to set up and you have to get the right adapter to fit your flashgun. I have seen the lastolite one used in a video and that looks a piece of cake and altogether more robust.

I think a softbox might be a bit cumbersome, you might be better off with a little Stofen diffuser or a Lightsphere