Thu 31-Jan-13 01:15 AM | edited Thu 31-Jan-13 01:23 AM by ZoneV
>I thought 1/320 fp allowed a shoe mounted flash, the >SB-800 or 600 in my case to sync all the way to 1/8000. Is >this the case? I like using fill flash outdoors to eliminate >shadows.
Yeah, but so does the 1/250 FP mode.
They are exactly the same above 1/320th. (And at 1/250th or below.) It's just within that narrow window between 1/250th and 1/320th that the two modes differ. You get a little more output (and faster recycling) in that range of speeds using the 1/320 option because the flash doesn't have to use multiple bursts (FP). The only reason to use 1/250 would be if you're afraid of the slight darkening that could occur along one side of the frame or need the full output. Note: a flash meter won't provide accurate metering when using the 1/320 option, either. In this case, the shutter speed does affect the flash exposure (and you still lose some output versus what you'd get at 1/250 because the shutter has already started to pass part of the frame by while the flash is still exposing the frame).
But when it comes to handholding a 300mm lens for fill flash, the slightly higher shutter speed can make the difference in a sharp picture.