From the Canon Digital Learning Center:
"As a commercial photographer for over 30+ years, my thought process has leaned towards using large strobe light systems in my studio and location photography and to keep the Speedlites for on-camera projects and mostly people subjects. Working with the Canon Speedlite 600EX-RT along with the Speedlite Transmitter ST-E3-RT over the last year has really opened up my mind into a different way of thinking about exposure control and lighting.See the entire article on the Canon Digital Learning Center.
Coming from being trained as a film photographer, lighting is something that I have tried to keep as constant like shutter speed, aperture and ISO. Digital was no different – you still need to get it correct in the camera. When working with strobe lighting, if I was happy with the composition, shutter and F-stop settings and I needed to change the overall exposure of an image, it was time to manually adjust the lighting. If the light were exactly in the right position already, I manually raise or lower the power output until I get exactly what I’m looking for. Now at this point, if lighting or camera settings change, everything would need to be reconfigured. For example, if you wanted to change the F-Stop setting from f/22 to f/2.8 for a selective focus effect, you would now have to manually dial down the lighting with some trial exposures to see if you got the exposure correct for the new settings. If you moved the lights in closer for a different lighting effect, it’s time to reconfigure the exposure again. The lighting and exposure changes can go on and on."