Just wondered how you test lenses for AF accuracy.
Reason I'm asking is that I've just sourced an 18-140mm VR to use on my Nikon D300 and on test found the performance to be woeful on my quick test target - church steeple and block of houses about a 1/4 of a mile away - this gives me some idea how well the lens will work for landscapes. Found that wide angle shots were poor at any aperture, stopping down made little difference, but it was better at 140mm.
Thought about sending it back, but wondered about checking af tuning, never needed it on any lens/camera owned so far (haven't used a D800E yet!). Tested a whole range of settings which made no difference until I went to +10 on the D300. All of a sudden the lens started to perform as expected, surprisingly, +9 or +11 were little better than the 0 setting, really expected performance to improve as I got nearer the optimum settings, but it was all or nothing! Wide angle seemed greatly improved, with not a great deal of improvement at the tele end, lens was now acceptable, BUT restricted to a Nikon af adjust body.
Tested my other lenses and found no improvement over the 0 micro adjust position. Wondered if your experiences were similar with lenses that needed micro af adjust?
Wondered if you've used any gizmos or other methods for af accuracy settings, as this doesn't check performance at close quarters, curious if users find any difference in af accuracy at different distances and the lens needs testing at a range of distances and then setting the af adjust to give the best overall performance. Wonder if this is an issue for users with very large sensored cameras?
Finally wondered if it is possible for a lens repairer to re-calibrate the lens so that it will give sharp results on the daughters D3000?
Reason I'm asking is that I've just sourced an 18-140mm VR to use on my Nikon D300 and on test found the performance to be woeful on my quick test target - church steeple and block of houses about a 1/4 of a mile away - this gives me some idea how well the lens will work for landscapes. Found that wide angle shots were poor at any aperture, stopping down made little difference, but it was better at 140mm.
Thought about sending it back, but wondered about checking af tuning, never needed it on any lens/camera owned so far (haven't used a D800E yet!). Tested a whole range of settings which made no difference until I went to +10 on the D300. All of a sudden the lens started to perform as expected, surprisingly, +9 or +11 were little better than the 0 setting, really expected performance to improve as I got nearer the optimum settings, but it was all or nothing! Wide angle seemed greatly improved, with not a great deal of improvement at the tele end, lens was now acceptable, BUT restricted to a Nikon af adjust body.
Tested my other lenses and found no improvement over the 0 micro adjust position. Wondered if your experiences were similar with lenses that needed micro af adjust?
Wondered if you've used any gizmos or other methods for af accuracy settings, as this doesn't check performance at close quarters, curious if users find any difference in af accuracy at different distances and the lens needs testing at a range of distances and then setting the af adjust to give the best overall performance. Wonder if this is an issue for users with very large sensored cameras?
Finally wondered if it is possible for a lens repairer to re-calibrate the lens so that it will give sharp results on the daughters D3000?
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