Hi all... First (or maybe second) time posting after several years here. I'm preparing to step into ULF after decades of 4x5 and 8x10. I need to build the camera for this move... a 16x20 was my first thought since it's always been my preferred display size for personal work. But now that it's actually time to commit and order a bellows for the project I'm thinking about infrequent commercial opportunities where 24" might be useful. I've heard step up backs impose serious lens focal length imitations on smaller formats (4x5 to 5x7 or 8x10 to 11x14) where the size differential is as high as 40%. But with 20x24" being only 20-25% larger than 16x20 I’m thinking a step up back would be a very serviceable solution for those instances where a little more is needed. Having never used a step-up back myself, input and suggestions from users with such experience would be most appreciated. Thanks