I'm scanning my BW negatives using a Canon 9950F and Vuescan. I've found that using the green channel gives the best results. Anyway, I'd like to adjust exposure, as it were, to get the most information from the negative, but I don't want to just be applying post scan adjustments, which I prefer to do in Photoshop. I'd like to be able to either very the intensity of the light used for scanning or the time. Is this possible?