Indeed. And my reason for asking was precisely to find out if there were any tips getting the maximum sharpness from the Apotar. I have though of counting the the notches round the rangefinder knob and relating them to those round the focus ring. There seems to be a 3:1 ratio up to about 4 feet and 2:1 above 8 feet. But between 4 and 8 feet it's around 2:5 which is a bit awkward. But the entire rigmarole of counting notches is a bit laborious. So maybe I'll just guess like everyone else.