Another thing to consider if you're dragging the shutter is color balancing the two different light sources. The flash is like daylight, about 5500K. OTOH, incandescent lights are much warmer 2500-3700K. If you just do nothing and the two sources are close in terms of exposure level, you'll likely have a mix of lighting on your subject and since the two sources are coming from different directions, your subject will have some areas illuminated primarily by one source and other areas illuminated by the other. If you're converting to B&W, it's not a problem, but if you look at something like a white dress in color, it will have distinct blue areas and/or distinct orange areas. It's nearly impossible to fix this in Photoshop.
The easiest way to correct this is to make the two sources the same color by placing a piece of amber "Full Sun" gel over the flash head and shooting with either a custom WB or the preset incandescent WB. It probably won't be exact, but it will be pretty damn close. |
