will47 wrote:
I have two Canon 580EX ll flashes and I want to start using them for with my Canon 100mm 2.8 Macro. I have no idea about how to go about this or what equipment I would need. I've even though of a ring flash?? I would not object to going with something other than the 580's that would fire remotely. In fact since I want to start using flash, for things other than macro, more often, what Canon product would do that? Thank you.
You just need one of your flashes, an off-camera shoe cord, a roll of white gauze bandage and a rubber band.
There are flash brackets that are adjustable so you can position the flash various ways, but I usually just hand hold the above for various shots.
That's what I used for:
The purpose of the white gauze bandage, which you can get at a pharmacy or most grocery stores, is to reduce and diffuse the output of the flash. The 580EX is way too powerful, even at lowest settings, to use up close. Two or three layers of gauze bandage work well. The rubber band holds it in place.
There are both Canon and third party clones of the off-camera shoe cord. Either should work fine. They often show up used on eBay, too.
I also have and use the Canon MT-24EX Twin Lite Macro and MR-14EX Ring Lite Macro flashes... But they are rather bulky and I don't always take them with me. Only when I'm sure I'll be shooting macro.
On the other hand, I pretty much always have a 580EX or 550EX in my bag, in case it's needed. It's quick, easy and cheap to set up and use as shown above. Put the flash in ETTL mode and you get auto exposure. If you use one of your camera's auto exposure modes (Av, Tv, P or M+Auto ISO) the flash will act as FILL. The camera will set exposure based on the ambient light conditions and the flash will fire 1.66 stops reduced output, as fill. If you put your camera into fully manual exposure mode (M without Auto ISO) and the flash is set to ETTL, you still get auto exposure though this time it will be done with FULL flash. The camera still meters and adjusts exposure, but now it's only measuring the flash and ignores ambient light. That is, unless you have the camera's exposure controls set to include more of the ambient light in the image. You can control it.
Regardless whether you are using the flash as fill or full, you can dial it stronger or weaker using Flash Exposure Compensation. In ETTL, that's done with the dial on the back of the flash, much like you do Exposure Compensation with the dial on the back of the camera.