I took a look at the owners manual for my Beseler 23CII and noticed that there are different numbers for different boards based on focal length. I've been using a 100mm lens for my 6x7 negs in both a Besler 4x5 enlarger as well as the 23C. However, I also shoot 135 and have a 50mm lens. Can't I use the same board for my 50mm as I have the 100mm in? It's the only board I have right now. Thanks for replies.