I have one lens that is used on 4x5 and 8x10. Caltar II-N (aka Sironar N) 240mm. To focus on subject X would require the same bellows draw from either camera. http://www.bobatkins.com/photography/technical/dofcalc.html Yet DOF calculators take into regard the film format. Should they? If the lens is set for f32 then the in-focus area remains the same, does it not? What am I missing?