Improving AF with some MF finetuning?

[danielchtong]

I have noticed recently one way of improving AF focus lock of my DA200mm is to manually shift the focus distance to infinity (BTW great shift mechanism) prior to shooting subject further away.
And if I am aiming at closer subject I manually shift the focus to min. focus distance.
By manually setting the focus distance, the lens can have only one way , instead of the other way, to lock focus of the subject.
The ideam came when I shoot my manual focus A300mm. I always set to around 120 ft mark as I usually aim at my subject around 80 ft away (for bif shots). In that way I always shift the focus ring counter-clockwise. That gives me more keepers in locking focus a lot faster.

Daniel

Originally Posted by Lowell Goudge

a great example is my sigma 70-200F2.8 it has 1/4 turn (90 degrees) from minimum focus to infinity. to make the comparison truely equal, add a 2x TC. Now I have 400mm F5.6 with an extremely narrow DOF and only a very limited adjustment range to get it perfect. Compare this to my manual focus vivitar 400mm F5.6 and I have amost a full turn (330 degrees) of fotation of the focusing collar.

[pingflood]

Nothing wrong with that approach. In fact, I saw a prominent bird photographer recently suggest using that for when you're using a teleconverter as those tend to impact AF performance a bit.

[simico]

Originally Posted by danielchtong

I have noticed recently one way of improving AF focus lock of my DA200mm is to manually shift the focus distance to infinity (BTW great shift mechanism) prior to shooting subject further away.
And if I am aiming at closer subject I manually shift the focus to min. focus distance.

I do the same when I change the FL from one end to the other (e.g from 50 to 200mm) or aim a closer subject after a faw away one. This shortens the time of auto focusing - the sound of the screwdriver AF scares aways my targets if it has to go through the entire focus range.