My personal macro and tele lens comparison

Hello AndersW,

thanks for your interesting input. I think there are many reasons for back focus, and your example was well chosen. I even thought that my wristwatch sample fools the 300mm lens the way you describe. Because the metallic lines shows some contrasty bokeh. But on the other hand the 60mm lens has similar bokeh and never fails to focus correctly. So bokeh and CA is not always fooling the AF logic.

Besides your explanation - which fits very well to your sample - I have another explanation:

For this, I have to look back at the slow but sharp FT 35/f3.5 lens. The 35mm lens focused veryyyyyy slow (1-3 seconds typically, often more), it was easy to observe the camera acting. It first made a sweep back and forward to find the sharpest distance. Then the focus drive made a big jump and locked at the exact position were the picture supposed to be sharp. I was wondering how the "jump" can be precise enough, but the 35mm lens always had perfect focus.

What if the 300mm lenses are controlled similar, but silent and fast. Maybe they make this jump but they miss the correct point because the macro lens changes the focus behavior quite a lot???

Christof

(P.S.:I am still thankful for your explanation of shutter shock, there was a lot of speculation going round and round. Your explanation as well as the pistol-grip trick made a lot sense for me. I screw my folded tripod under the camera to mimic the pistol grip mass and viola: the shutter shock with the 300mm lens has gone. Thanks!)