Occasionally, manufacturers speak with forked tongues.Originally Posted by Robert
I wonder about the inclusion of the word "repeatablity" ... If one was to set a meter on a rigid support and measure a non-changing, evenly illuminated target, I have no doubt that the multiple readings could *repeat*, that is, one would get the *same* readings, all the time, within ~ 0.1 "EV". Not hard to do. Accuracy, where the reading you get conforms to the *true* value, is not the same thing. Accuracy is conformance to true values - "repeatablity" is properly known as "precision"- so "repeatablity accuracy" means -- I'm not quite sure.
This whole 12% - 18% reflectance bias is a pain in the butt, anyway... that all depends on the *assumption* of the meter manufacturer - whether the "average " scene reflects 12% or 18% of the light falling on it... and that is directly related to the reflectance of the objects in the scene.
One intersting "test" is to take a meter reading of an 18% gray card, and in the same light, take an incident meter reading and note the difference.
I wish someone would produce the *ultimate* meter - one with different, selectable, reflectance values ... like the metering system in the Olympus OM-4. One has the choice of 5%, 18% or 95% reflectance - and spot, averaging, and true Off-the-Film flash metering. That has been called the most sophisticated metering system they ever built a camera around.