Sir
I am just learning large format focusing. On my 4x5 using a 150mm lens it has been easy to focus. I focus on my main subject placing it in the middle of the screen, tilt the bottom of the film plane toward the lens board to clear up the bottom half of the screen and then barely tweak the lens board and everything is in focus. My 4x5 is axis tilt on the film plane and the lens board has bottom tilt. I have used the same basic technique using a 360 mm lens on the 4x5. However when I use the 360mm lens on my 8x10 the same technique does not work as smoothly and I have to do a lot of focusing to get a correct screen. Yet when I go to a 240mm G-claron the focusing is much easier. My 8x10 is axis tilt on the front and back. What is going on? Does my near point change by going to a longer lens? Are shorter lens easier to focus? Yet why does the 360mm focus easily on my 4x5 and not my 8x10? Any thoughts would be greatly appreciated.
Jerry Cunningham