First a little background info for those unused to flash photography. Bear with me, it sets the scene to explain my issue. If you're shooting a mix of flash and ambient, say a flash lit subject and the rest of a room lit by whatever lights there are, you gel the flash to match the colour of the ambient, then set your white balance for that - voila, natural looking light and colours. So I was trying to get the right combo of gels + WB to work right in my living room and was being frustrated, here's why: So I choose an incandescent WB setting, fire a test frame: Looks good. I pop a flash trigger in the shoe, fire off another (note no flash): Urrg it's gone all orange! What's going on here is that the WB is auto correcting assuming the entire frame will be lit by white flash, even through it's not (no flash was set to fire). The camera assumes if there's something in the shoe, white light will flood the scene. Annoying! There is a way round this though. As a rough start (i have energy saving bulbs, not incandescents) I figured a full CTO gel was a good start, so I dialled a custom WB to match (3200K): Looks ok (empty shoe). But here the behaviour differs! Thankfully at least in this setting, with a trigger in the shoe, the WB isn't changed: Woohoo! Anyhow, hopefully that helps others! Maybe this is expected behaviour? But I didn't expect it at least. So the message here is: If you're gelling your flash(es) to match ambient, use a custom white balance!