E-TTL and Lastolite HiLite

Basic question alert!

I wonder whether anyone can tell me if this is a practical way to use the Lastolite HiLite (or, I guess, other backdrops). I'm asking the question rather than trying it myself because I don't have preflash-aware strobes.

What I am trying to get is the benefits of E-TTL to let me correctly expose the subject of a photograph, while still using the HiLite for a nice white background.

My idea is that I set the HiLite up using appropriate strobes and a preflash-aware controller. I use a flash meter to get the HiLite up and set for, say, f/8. I set my camera up to 1/125s, f/8 and if I shoot the HiLite, I shall get a pure white back

Then I bring in the subject. I have my 580EX E-TTL flash mounted (probably through a large brolley) and connected to the camera via an off-camera cord. I probably have it set up with a fair amount of positive FEC, because a lot of light from the preflash is going to bounce off that nice white HiLite and confuse the metering system

So I take my picture. The 580EX sends out its preflash, and works out how to meter correctly for the subject. Then it sends its main flash, and the HiLite lights trigger.

So I end up with a nice white background and beautifully exposed foreground.

Should this work, or am I missing something?

regards,
/alan

I do the following with my HiLite.

I put 3 580EX's (slave mode) physically inside the HiLite which saves tons of side room if that's a problem. (2 can work okay too depending. I like 3 for faster recycling times.)
I use a broom/stick to align them inside the way I want them using the included plastic stands. This is good because I can adjust the flash output from on camera.


I have a 580EX on camera in master mode to control the flashes in the HiLite.

I than have a CyberSync attached to the side port which fires a strobe for my main.

I see you have a 350D, so that kinda' keeps you from doing it the way I do due to lack of a PC port.

You seem to want to do somewhat opposite as far as where the flashes go.
Assuming the device you are using to detect the pre-flash works, I can't see a problem with what you're doing. You would just want to meter the non-ettl flash separately I believe.

I'm sure others will chime in, I wanted to just point out what I do to mix flashes and a HiLite.

-Mario

Why not keep it simple and use your 580ex (for the subject main light) in manual mode? Why you want eTTL in this case?

Thanks for the suggestions. The rationale for doing this was that the subject might be in different positions (standing, lying down etc) and by using E-TTL I would be able to get more consistent exposures without having to re-meter every time I had to move lights around to suit the subject's position

regards,
/alan