Apologize up front for the spate to of stupid questions I will be peppering you guys with in the coming weeks/months. Finally got my 4X5 Calumet all together, culled a boatload of film and half-dozen good carriers and am now waiting for some sunshine. I have exposed processed 20 or so sheets . . .first dozen were destroyed in a darkroom fiasco that I can't get into right now. If there's a million ways to screw it up, I'm on about #4. I do have a couple of books on LF, so I have some clues. Question #1: Is it necessary to refocus after stopping the lens down? I understand the depth of field will change, but will the actual focal point change at all? I really have a tough time seeing anything stopped down to f16 or less. Maybe I need a heavier dark cloth, or maybe this is just the nature of the beast.