Quote Originally Posted by marciofs View Post
Exactly.

I also have tried to focus without looking into the viewfinder but looking at the distance of the subject. And it is easier with wide angle lenses. But I will only know if it works ok after finish the film roll.
This is elementary and only works well with lenses stopped to 5.6 or smaller and wide 35mm lenses. No way you will get much by this estimation method and 70mm or longer lenses. It's kinda silly with an SLR, unless you are setting the hyperfolcal distance for quick photography.