I use glass carriers I over 10 of them, and I have dedicated full frame indicators on the back side of each one for each format. This allows me to always know where the dead center location is. And yes I always move the negative into position rather than move the easal.... this is what I am trying to point out to the OP and of course Doremus.
On one of my threads I have alluded to this practice, learned after years of making mistakes....
Moving the easel for crop is a very bad practice... a hair ok but the sweet spot is the sweet spot , no sense arguing this from my point of view... others may like burning in edges and having soft areas, I prefer even light and sharp corners.


Quote Originally Posted by tkamiya View Post
Bob?

In your own practice, if you have to crop, do you move the film so that your easel is always located at the dead center of the optical axis of the lens?? I move the easel myself....