100-300 or 75-300?

Well, I know what you mean to say, but sample variation means precisely what it says. That each lens will measure different depending on the quality of that particular sample. Assuming the same test conditions.

What I think you really meant is that there is more variation in the quality of the actual test methods and results than in the samples themselves and of course you are dead right. Most people cannot test their way out of a wet paper bag  By which I mean that few people really try to control all the variables and few use any real formalism while testing ...

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