Back in the day when you had to actually focus an SLR yourself, the focusing screen image was quite large and wide and frequently gave a 1:1 image when a 50mm lens was on the camera. I notice that post 1980s autofocus cameras, like Nikon f100 and n75 have what I call 'tiny' focus screens. I presume because the camera will focus for you and you don't need to see the image 'close up.' In fact the n75 gives a 1:1 view only with an 85mm lens. So I wouldn't even try to use that camera (or the F100) with manual focus lenses.