- Nov 17, 2015
Hey Yall! Not native to forums but I was hoping someone could help me out. I recently built a 14x17" ULF to shoot CTX green lat xray film and it was perfect, almost. I was looking to build a lighter, collapsable, monorail field camera but I am having trouble wrapping my head around lenses. I've read that most people shooting ULF use 500mm lenses with ease. However, I am a broke medical student and want to try to use my Schneider-Rodenstock 150mm f5.6 or my Caltar ii-N APO 210mm lens. Is there a way to use them? I have a 52cm rail so I dont think racking out will be a problem but I can't for the life of me find any formula or a simulator or anything on DIY ULFs and lenses/conversions. the 150mm len is charted, focus at infinity @f16 to have a image size of ~8" and that's at ~6" distance lensboard to plate. I think racking out the bellows will give me the coverage I need but I can't seem to get any straight answers on if i'll be able to focus at all with 150mm or 210mm lenses. From my understanding, which is really poor when it comes to optics, is that at 150mm from lens to board I will be focused at infinity and to focus on things infinitely closer I need to rack it out. But is there a tried and true formula for what that distance would be for focusing between ~8' and 20'? Does anyone know anything? I'd rather troubleshoot and get my distances right before I make the bellows. Yall are just wonderful, thank you for the help!