Wireless flash question

[fastson]

Hey all.

I recently got a 2nd flashgun (F42AM) so I am experimenting some more with wireless triggering, but I found one "problem" that can be pretty annoying at times. The pop-up flash on the camera contributes light to the picture I am taking. Sometimes this can be nice, but most times I'd rather not have it.

Right now I am holding my hand in front of the pop-up flash to hinder its light from hitting the object I am photographing.

However, I thought I'd ask you guys here if you have any better solution? Something that can be put on the flash but does not mess with the signals it needs to send to the salve flashes?

Here are two quick examples. Wireless flash to the right firing into umbrella.. Picture 1 is taken without me holding a hand in front of the pop-up flash, in the 2nd picture I am.
You see the harsh shadow behind the headphones and how the plastic has that ugly reflecting light on it.

[KevinBarrett]

Another member, a long time ago, said that he used unexposed 35mm negative film after developing. You must wind the film back without any exposure, send it to be developed, and then cut a piece out of the negatives large enough to cover your pop-up flash. This will block visible light but not the infrared signal that the flash guns use.

I might be sketchy, though, about what kind of film it was to be used.

[fastson]

Thanks Kevin.

I'll have to check and see if we have any such film. Otherwise I have an excuse to try out my fathers old Konica camera, take some shots and send the film in.

[Greg Beetham]

I only know of two reasons, one is too high an ISO, the other is bad comms (line of sight) between the camera and the slaves and the onboard flash assumes more of the responsibility for the exposure, you might find that one of the 42's didn't even fire for example.
Greg