Simply the best flash made by Canon and the right way to go for professional use. If your not making money off this unit you could step down a model but if your going to step up and start making money this is your model.

The Canon Speedlite 600EX-RT flash represents a significant new release for Canon photographers, most specifically for those using off-camera flash. A very capable and reliable flash on its own, its real forte is when used as the heart of a radio-controlled flash system.

Daunting is sitting down at the keyboard to attempt to do justice to a review of Canon's flagship flash, the Speedlite 600EX-RT. Few aspects of an image are as important as the lighting – arguably being second only to the subject and perhaps the composition?

Canon 600EX RT (18.7 oz./529g with 4-AA eneloop cells, 2.5 second measured recycle time, measured ISO 100 guide number of 29 meters/95 feet at 35mm, rated guide number 36m/118' at 35mm, 20-200mm zoom head with 14mm wide panel and catchlight card, about $470 new ).

Flash units are useful for people who own a professional digital camera, especially those with a DSLR who would like to make the most of the range and versatility of lenses that are available to them.

I have tested these flashes in very extreme circumstances where I anchored multiple flashes directly to an ice waterfall. The flashes fired extremely well and gave me great confidence that I could use these flashes anywhere.

I've used this flash many times for both indoor and outdoor photography. I've never had a single issue whatsoever. There are a range of different settings which make it possible to use in many different situations and lighting conditions.