I developed a couple of 8x10 negatives last night taken at the Zion workshop and they look like they might be underexposed by a stop of so.

I was using a G-Clarion 240mm lens in a NEW copal 1 shutter and I fear that I may have screwed up when I made the f/stop scale resulting in underexposed negatives shot with this lens.

I'm going to develop one more negative taken with this lens to try and verify if there is a problem.

If the next negative does turn out underexposed would it help to extend the development time on the others?

If so how much should I increase the development time?