Speedlight Flash lighting w/ Zoom lenses - SB-700 & Nikon 55-200mm

BobSC wrote:

With flash photography, there are three variables:

• aperture
• distance
• flash power (& ISO)
  

The focal length of the lens doesn't matter, and neither does the shutter speed.

The sb-700 has a zoom head that concentrates the flash power. If you had it on the long setting, then it has a guide number of 95 at iso 100. If you had the lens wide open (f/5.6, right?) and use direct flash, then it should work at 17 feet (5m). If you bounced it off the ceiling, then a lot less. If you put the iso to 200, then 24 feet. at 400 then 48 feet, and so on.

If you were bouncing, then you lose at least two stops of light. So then at iso 400 you get back to 17 feet, or less.