hi, very hard to find definite information on this so i thought i'd ask. is it true that some durst enlargers like the f30 and f60 have an adjustable enlarger bulb position? is this for focusing the bulb directly onto the condensers? or is the bulb's light reflected of a white surface onto the negative like a diffusion setup? is the m700 ( older ones, not the colour head models like the m605, 805 etc ) also similar to the f60 in lighting setup? thanks for your help.