I've been rolling a few APX100 and FP4+ in my Yashica-D in the last few weeks, and I'd like to start assessing its features a little more closely. Although I've been shooting often, I haven't printed anything yet, so if my reasoning is flawed because of that, please stand up.

Basically, I'm trying to understand what is my lens' (Yashikor, 3-elements) impact on contrasts, in order to see whether I should shoot with a yellow filter all the time. By looking at my contact sheets, I have the impression that contrast is not very accentuated in my pictures. Even with more/less exposure, I tend to get a slightly narrow range of values on my contact than I'd like.

My first deduction was: a contact sheet of roll film is a print that is not optimized for any specific pictures, therefore it's only there to give a positive image. However, when comparing on the same sheet pictures taken at different degrees of exposure with pictures taken with a yellow filter, the yellow filter ones win. I have a wider range of values, and that is what should be expected of a K2 filter.

So how do you assess the contrast in your negatives, besides printing them? How can I get an idea of my lens' impact on contrast? And why are certain lens more contrasty than others in the first place? Is a contact sheet notoriously bad for assessing contrast?