Help me choose a flash setup

Im trying to decide if I want to buy a bracket like this http://www.ebay.com …7176104330&_qi=​RTM2067270 and use 2 speedlite 270's with a dual ettl flash splitter, or just one 430ex with a snoot. Are there any cons to using the single flash over having the dual setup? With the dual setup I was hoping to get side and top/backgroud illumination. With the single 430ex I would hope to accomplish both with the more powerful flash as some seem to do on here. With the 430ex I would use a standard bracket for the flash, maybe a ballhead. The lens I will be using is a sigma 50mm F2.8 macro lens. thanks

Having a "more powerful flash" won't help you to illuminate the background. The flash is going to turn on long enough to provide enough light to expose the subject, and due to flash fall off the background is going to be black unless there is something close to the subject to reflect that light back into the camera. You could use two flashes, one to expose for the subject and the other for the background. But you're going to have to set that background flash manually since E-TTL flash metering will only turn the flash on long enough to expose the subject.

If you see someone shooting at 1x or higher magnification and the background isn't black then they are doing one of two things:

Put something in the background, close to the subject, to reflect light back into the camera. In this case an artificial flower:

IMAGE LINK: https://flic.kr/p/toqC​N1

IMAGE LINK: https://flic.kr/p/vfAT​ZH

Are you saying that the iso and aperture communicate with the flash but the shutter speed does not? I really don't know much about camera flash so it is some what of new territory for me. Would using a secondary flash in curtain mode illuminate the background? Also would the initial flash freeze the action while the exposure completed? Sounds like its going to be alot of fun to learn.

calypsob wrote in post #17639509
Are you saying that the iso and aperture communicate with the flash but the shutter speed does not? I really don't know much about camera flash so it is some what of new territory for me. Would using a secondary flash in curtain mode illuminate the background? Also would the initial flash freeze the action while the exposure completed? Sounds like its going to be alot of fun to learn.

"Are you saying that the iso and aperture communicate with the flash but the shutter speed does not? " Unless you go above the flash's sync speed the shutter has no impact on the flash itself because the flash fires so quickly. But changing the sensitivity of the sensor (ISO) or the size of the len's aperture (Fstop) will impact how long the flash turns on.

"Would using a secondary flash in curtain mode illuminate the background?" Second curtain sync wouldn't make any difference. It would depend on how close the flash is to the background, how close the background is to the camera's sensor, and can the flash produce enough light to be seen by the sensor with the camera's ISO and Fstop settings.

"Also would the initial flash freeze the action while the exposure completed?" Yes, as long as it's the only light source hitting the subject. If you are close to the natural light exposure then you could record some motion blur if the subject moves while the shutter is open. I set my flash to second curtain sync to help freeze motion just in case there is too much natural light. I was either too close to the natural light exposure for this honeybee, or I didn't completely shade it and there was some sunlight hitting the antenna. But I did manage to capture the detail in it even though it clearly moved. Natural light exposed the background:

IMAGE LINK: https://flic.kr/p/vhFZ​id