Posted by Larry Fischer on January 2, 2010 at 9:32 AM
Purchased the above lens and gosh was it soft at f/2.0 and for several stops thereafter. An this is supposed to be one of Nikon's sharpest lenses.
There was, in my opinion, significant particualtes in the inner lenses so I sent it to Nikon. They cleaned and evaluated.
Photos thereafter were the same--no change.
So instead of using the "pumpkin-head" focus light (infiinity should not make a difference for things at a distance, right?). I experimented with backing off slightly. I found when the left triangle indicator was the only item showing in focus, the lens would perform, ie. give a sharp photo.
I have other older prime lenses but have not noticed the focal-plane problem, if that's what it is.
Comments would help. Could there be other issues?
I'm not anxious to have a rogue lens with different focus issues--I'll forget it idiosyncracity at a very inopportuen moment.
the fisch
Posted by Basil Greber on January 4, 2010 at 1:56 AM
Sounds strange for sure. Maybe the lens has some uncorrected aberration (residual spherical aberration or what ever...?) that fools the AF sensors? Does focus change when you stop the lens down? You may probably best evaluate this when focusing in live view.
Posted by Larry Fischer on January 4, 2010 at 7:38 AM
Basil,
When the lens is stopped down eventually it will take a decent photo.
But, my take on that, is the depth of field is increased and the focal plane depth (circle of confusion) then encompasses the sensor. It just won't focus wide open without a slight adjustment which could be frustrating. Why have a fast lens it it won't work wide open??
Discussion
2 repliesThere was, in my opinion, significant particualtes in the inner lenses so I sent it to Nikon. They cleaned and evaluated.
Photos thereafter were the same--no change.
So instead of using the "pumpkin-head" focus light (infiinity should not make a difference for things at a distance, right?). I experimented with backing off slightly. I found when the left triangle indicator was the only item showing in focus, the lens would perform, ie. give a sharp photo.
I have other older prime lenses but have not noticed the focal-plane problem, if that's what it is.
Comments would help. Could there be other issues?
I'm not anxious to have a rogue lens with different focus issues--I'll forget it idiosyncracity at a very inopportuen moment.
the fisch
When the lens is stopped down eventually it will take a decent photo.
But, my take on that, is the depth of field is increased and the focal plane depth (circle of confusion) then encompasses the sensor. It just won't focus wide open without a slight adjustment which could be frustrating. Why have a fast lens it it won't work wide open??
the fisch