Speedlight test fire output vs camera fire output

<p>Using a P67II, and a flash meter with my Pentax AF-540fgz set to manual at 1/8 power on a light stand. When I do a test fire from the flash the meter reads f/5.6, when I fire from the camera via cable the meter reads f/6.3. The light stand didn't move and shutter speed didn't change. Can anyone explain? Thanks.<br /> IW</p>

<p>Is anything about where you're placing your body when you meter from each position, what clothes you're wearing, etc., change how much light blocked/reflected, etc? I've had situations where whether or not I turn my face away - as I hold the meter - makes a stop's worth of difference in some lighting situations, as the meter sees it. That's what I get for having a large, lilly-white face!</p>

<p>Thanks, Matt. I did a test and you were right. I must have been blocking some window light when test firing.</p>

<p>Hey, I'm glad it was something that straightforward (because, you know, sometime it just ain't!). Unless there'a a bright floor or low reflectors involved, I've taken to doing most of my metering by crouching low and holding the meter up near the object/subject in question. Been burned several times by blocking/reflecting certain paths from a given light source to the scene, or just altering the way things bounce around. Good luck with your project!</p>