I have acquired two Meyer Optik Trioplan 50mm f2.9. One is a "V" version (coated?) one is not. So I wanted to do a quick ghetto test last night and see which one is sharper. I placed some fine printed info (paper material) on a flat surface an shot with the lenses at 90° angle. At wide open f2.9 it was kind of hard to focus really accurately (subject 10 feet away) and I resorted to magnified view (14X) on my back screen of a Olympus E-P5. Then I proceeded to stop down the lens to see how the sharpness improved. To my amazement the lens did not sharpen the image although it was more contrasty than wide open. At f5.6 the image was way worse than at f2.9.... WTF? Wait a minute, I said. So, start again at wide open, get it sharp and then close it down. This time I check the focus as I stop down and guess what: substantial focus shift! As I stopped down I readjusted my focus and things got indeed better than wide open. What was focused sharp at f8 was NOT at f2.9, and th eother way around. The same happened on the second Trioplan 50mm :-( So, my old school learning are not holding true on this lens. For years I have been achieving best sharpness with (auto) lenses by focusing at wide open and then the lens stopped down to the desired f-stop setting when the shutter was pressed. That is from film days with Nikon lenses, Minolta and Schneider (on Hasselblad). Do any of you notice serious focus shift on your vintage lenses?