How long should be a bellow on a 20x24 camera if I want to take portrait in a studio ? I know that it depend on the lens I will use and that I should have a bellow that is twice longer than the lens, so that I can use the 1:1 ratio... but what would you consider a good lens to make portrait on this kind of camera ? In fact at the biginning I will only use 16x20 sheet film in vertical position inside the 20x24 film holder that would be in horizontal position... Sorry if my english is not so good, I hope my questions are clear ? Thank you, T. Moenne-Loccoz.