Response to Variation in density of edge markings - FP4

This is armchair theorizing- I have no inside knowledge, your mileage may vary, and all the usual disclaimers apply. If you were making film, you'd want the edge printing legible. You'd also want to expose the film to the minimum of light to avoid any risk of fogging via light piping or stray light. You wouldn't waste money regulating the light source, or in maintaining consistancy (bulbs?). If you had several machines doing this (likely) you wouldn't worry about minor or even major differences between them- why bother? Production machinery isn't always built at the same time and may not even be of the same optical design. Or run at the same speed. Thus, I suspect judging *anything* by marking density is a complete waste of time. Besides, the marks are too small to measure easily. I do something I think is better, but is still frought with error sources. I make a quick density measurement of the exposed leader of each roll. This should be somewhere near Dmax and gives me at least some confidence that my processing is consistant. Not great, but better than looking at edge markings. You can even do it without a densitometer by comparison with a step tablet.

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