I have a nikon pb-6 using it on the f3 with several enlarging lenses. I have lenses from 135mm down to 35mm. I found the longer focal length lenses are more useful. With even the 50mm, I found that I have to get too close to the subject. Also my 35mm lens was designed for 126 negative and thus there is minor light vignetting at the corners. I think the 28mm would cause even more vignetting.