For macro images that need extra light you should always use a tripod and if you still need more...try a ringflash. The lens will get in the way of the standard flashes.
I really like the idea of using the flash off camera with the cord, but how in the world do you hold the camera in your right hand, flash in the left, AND manual focus at the same time?
I really like the idea of using the flash off camera with the cord, but how in the world do you hold the camera in your right hand, flash in the left, AND manual focus at the same time?
The off-camera hotshoe cord is a good suggestion, especially combined with a flash bracket. Now you can place the flash where you want it and still have both hands available to handle the camera. Using a bounce card (I use a Lumiquest 80/20 with a silver or gold reflector insert for this) on the flash, with the flash mounted on-camera, will bring the light source up high enough to get good illumination, and provide a more diffuse light source. I commonly use this strategy and it works well. I do prefer the flash off to the left, still using the bouncer on the flash. This gives the advantage of diffuse light but retains some soft shadows for a natural-looking result.
In short, a dedicated macro flash is really not necessary at all.
I've had the best luck with my sb600 either on camera with a lumiquest softbox (or softbox mini) or at the very least a stofen omnibounce...The best thing about the sb600 is you dont need the cord to shoot it off-camera, so that helps too if the situation needs it.
You may find yourself even more limited with the 60mm being thaty our working distance is so close to the subject, it gets really hard to position your light...so for that reason, you may want to get the bracket and keep the flash off-camera.
Most of the time I'm using a 105 2.8, anywhere from 20mm to 68mm's of extension tubes and a 1.4x teleconverter. So I'm getting 1:1 at maybe 15 inches away and 3:1 at like maybe 5 inches or so...I could be way off, but that seems about it. I think you'll get 1:1 at your min. focus distance, whatever that is.
A ringflash was mainly invented for precision stuff..most of the folks out there that are shooting macros and really good at it aren't using ring flashes, just so you know.