Sigma

Hi everyone... I have another flash huh?...

If you read my other thread, I was having an issue with my Sigma EF-500 DG. Well, I picked up a 430ex II and I am very, very happy with it. One of the problems I always seemed to have was the flash overpowering the situation sometimes. Inside I resorted to bouncing the flash to get good images. With the 430ex I don't have to do this. The camera and flash work together (it seems) to expose the shots properly. It's awesome!

Now for my huh... With my Sigma sitting there, I thought I try a feature it has. I put it in the mode (I don't know the name) where on a tripod I can set it up as a second flash that fires on it's own when it detects another flash going off in the room. However, ther really, really odd thing, is that when I set it all up, and the sigma fires, the shots are always underexposed. I shut it off and take the picture again, the image is great (thanks 430ex. ). Why would this be happening? I would expect that because the 2nd flash is firing, and the camera does not know about it, it would cause an overexposed image... but it's doing the exact opposite? it's got me scratching my head.

Any ideas why this is happening?

Read this thread: https://photography-on-the.net/forum/showthre​ad.php?t=620744 completely to the end.

When you use the C0 SL mode on the Sigma with a 430EX on the camera, then the pre-flash of the 430 causes the Sigma to flash, the camera sees both flashes and says "use a very short duration on the 430", so then the 430EX does its shutter-open flash at short duration, but the Sigma may not have recycled depending on what output (1/1 is the default) you have set on it.

Thus you have fooled the ETTL system of the camera twice. It all makes sense to me and is not a problem with the Sigma, but with how you use it.

You need to have the 430 in manual mode so it doesn't emit a preflash. Set both flash power manually and set the camera in manual also. Play with it until you get the lighting ratios and exposure you are looking for.

Ahh... that's it. I set the Sigma flash output to 1/8th and it's able to keep up with the 430's preflash. Now I get what I expect... Over exposure until I arrange the flashes, and play with all the settings.

I didn't realize that the 430 emits a pre-flash. Maybe, had I read the manual I would have figured it out.

Thanks!