01-24-2018, 10:12 PM
I suspect the gear and "screw"-drive of the lens just has too much play.
It's weird that the AFMA is that widespread. Usually, with the new drives the difference between AFMA @ ∞ and closest distance is max 4-5. If the focus to the other sie of the river and close distance already reaches 20 and more, I suspect damage or wear of the focus transmission gear.
Nikon AF: AF-S means you push AF-ON (or half press shutter button), the lens tries to focus and stops, if the target is reached. No more correction until I press the AF-ON again.
AF-C means, focussing is still active as long as I press AF-ON or shutter button. I can set up, if the shutter releases or not if it's focussed (shutter or focus priority).
I don't know, dave: is there some kind of a clutch in the lens? Meaning, can you stop a movement of the focus ring, or can you turn (override) the focus ring when AF is active? Because if so, I would guess, somebody has used a bit of violence.
I know you're no fan of Sigma AF reliability. But I'm no fan ofd cheap lenses as they are sometimes cheap for an unpleasant reason :unsure:
It's weird that the AFMA is that widespread. Usually, with the new drives the difference between AFMA @ ∞ and closest distance is max 4-5. If the focus to the other sie of the river and close distance already reaches 20 and more, I suspect damage or wear of the focus transmission gear.
Nikon AF: AF-S means you push AF-ON (or half press shutter button), the lens tries to focus and stops, if the target is reached. No more correction until I press the AF-ON again.
AF-C means, focussing is still active as long as I press AF-ON or shutter button. I can set up, if the shutter releases or not if it's focussed (shutter or focus priority).
I don't know, dave: is there some kind of a clutch in the lens? Meaning, can you stop a movement of the focus ring, or can you turn (override) the focus ring when AF is active? Because if so, I would guess, somebody has used a bit of violence.
I know you're no fan of Sigma AF reliability. But I'm no fan ofd cheap lenses as they are sometimes cheap for an unpleasant reason :unsure: