flash setup problem

[Cutter]

I tried to take a portraite shot outside using a speelight at the front and a flash at the rear to seperate the model from the background, but all I got was my model lit up and a black backgound, anyone any ideas what I am doing wrong ? my camera was set to 250ss f9 then wentdown to 60th ss at f9 still the same result.

[matt wilson]

although it's imperceptible the speedlight may be triggering the rear flash too soon(it relies on a pre flash to calculate exposure in ettl mode.).My guess is the two guns are not in synch.

if the second gun is a Canon then it will synch using the 580 as a masterotherwise you will struggle unless you go into fully manual modes .

[Forseti]

More information needed i.e. type/make of flash used at the rear, how was the Speedlite set up and what method were you using to trigger the second flash?

Edit: sorry Matt - we appear to have posted at the same time LOL

[matt wilson]

have a look here for more on multi flash work .

http://web.canon.jp/imaging/flashwork/index.html

[matt wilson]

I thought I can run a Jessops cheapo as a second gun .Unless I go manually I can't .And then it is a pain .Will probably get a second Canon gun at some stage and then it's easy.

[Cutter]

I used my 580 speedlight on camera, and interfit flash behind the model triggered by 580 flash, hope thats enough info!!!!!

[matt wilson]

It will depend on the sensing ability of the interfit.(that is what is triggering it? )

As I said the canon puts out a burst of flash before the main one but this is so quick you can't see it.The interfit may see it and thus fire too soon in relation to the Canon gun.

Other thing to think about is whether or not there is a direct line of sight between the 2 flashes

[Cutter]

:

Originally Posted by matt wilson

It will depend on the sensing ability of the interfit.(that is what is triggering it? )

As I said the canon puts out a burst of flash before the main one but this is so quick you can't see it.The interfit may see it and thus fire too soon in relation to the Canon gun.

Other thing to think about is whether or not there is a direct line of sight between the 2 flashes

I think you are misunderstanding me! prob my fault. Both flashes worked, it was taken in daylight it lit up the back of the subject and the front but I got no background behind the subject which were trees, it was all dark. Does that make sense ?

[riddell]

Very simple.

Though you do not give a lot of information, the end answer one way or another is that at the end of the day your subject, i.e. your model has too much light on her.

What you need to do is meter the scene, ambient light, that in the background and that falling on the foreground or wherever and then dial the right settings into your flash to balance things.

At the same time you'll need to balance the exposure between the short duration of the flash and the possibly longer shutter requirements for the background.

Paul
www.photographybyriddell.co.uk

[Cutter]

Originally Posted by riddell

Very simple.

Though you do not give a lot of information, the end answer one way or another is that at the end of the day your subject, i.e. your model has too much light on her.

What you need to do is meter the scene, ambient light, that in the background and that falling on the foreground or wherever and then dial the right settings into your flash to balance things.

At the same time you'll need to balance the exposure between the short duration of the flash and the possibly longer shutter requirements for the background.

Paul
www.photographybyriddell.co.uk

Thanks paul I think that makes sense, any chance of an example. I have a canon 50d a 580ex2 flash and no hand held metering system. I cant understand how to meter off my camera. although I probably do it and not realise.