[Matt5791]

Other than instinct and testing, I've found this Ilford tool really handy. It is an enlrger light meter of sorts called an EM10. really cheap and very accurate. You can measure a highlight then enlarge then re-set to the same spot, and finaly adjust the f-stop till you have the same exposure.

What does this ilford tool look like? I bought all my darkroom kit on ebay as a job lot and there is this Ilford thing with a dial and little lights that light up as you turn it. It is white and about 4" long by 1.5" wide.

Mabey this is the thing!!