The SL66 is my MF weapon of choice. My waistlevel has a loupe that flips up and that is what I always use. When my eye covers the loupe, the waistlevel finder is in the dark. Never a problem in sunlight or dim. I have never been very good at using the waistlevel finder as it was intended. I just can't tell if it is in focus from that distance and with my middle age eyes, it has got to be the loupe. - Frank