friedmud
Senior Member
I bought a 24-70 f/2.8G and a 50mm f/1.8G with my D600 two weeks ago. The 50mm has been unbelievably sharp... with focus being spot on. But, over the last two weeks I've noticed quite a bit of weirdness with the 24-70... a lot of shots look great with focus being spot on... and others are soft. I also don't think I've been getting the resolution I should out of this lens, especially at the edges (even stopped down, on a tripod, with a 3 second shutter delay things are a bit "smeary" toward the left side).
I was doing some (informal) testing over the last few days and I noticed that all of my shots at 24mm are heavily front-focused. I started dialing in some adjustment and noticed that I needed quite a bit (~7-10) before shots looked in focus at 24mm.
Today, I decided to get more scientific about it and set up my own "lens align" kit (also known as a vertical target with a yard stick sitting next to it at an angle). I started with no adjustment and shot at about 40mm... comparing contrast detect AF (i.e., AF in Live View mode) with phase detect AF (i.e. "normal" autofocusing through the viewfinder) using spot focus in the middle of the frame for both.
At ~40mm everything looked "ok" not much difference between the two autofocus modes. At 70mm everything still looked ok (a little front focusing but not that much). At 24mm.... it is totally off. The DoF _totally_ misses the target (yes, even at 24mm where the DoF is fairly large) using phase-detect ("normal") AF.
At this point I started trying to dial in the proper AF adjustment... and I settled on about +15 at 24mm! That is huge. At that setting things looked pretty good when autofocusing around my office though.
However, using this setting I then tried 70mm... and it back-focuses. Not a huge amount, but it is evident. Then I try ~40mm... and now the DoF at 40mm _totally_ misses the target... back focusing beyond the target. Craps.
I believe that something is actually wrong with the lens. This isn't a tolerance thing. I think that an element must be de-centered or something along those lines (de-centering would explain the lack of sharpness on one side of the image as well).
I'm not going to mess with Nikon on this one. This is a $2000 purchase that is less than 2 weeks old. I think it's going back to the reseller for replacement on Monday. I bought it online... now I'm wishing I hadn't (much easier to take it back to my local shop...)
What would you guys do?
I was doing some (informal) testing over the last few days and I noticed that all of my shots at 24mm are heavily front-focused. I started dialing in some adjustment and noticed that I needed quite a bit (~7-10) before shots looked in focus at 24mm.
Today, I decided to get more scientific about it and set up my own "lens align" kit (also known as a vertical target with a yard stick sitting next to it at an angle). I started with no adjustment and shot at about 40mm... comparing contrast detect AF (i.e., AF in Live View mode) with phase detect AF (i.e. "normal" autofocusing through the viewfinder) using spot focus in the middle of the frame for both.
At ~40mm everything looked "ok" not much difference between the two autofocus modes. At 70mm everything still looked ok (a little front focusing but not that much). At 24mm.... it is totally off. The DoF _totally_ misses the target (yes, even at 24mm where the DoF is fairly large) using phase-detect ("normal") AF.
At this point I started trying to dial in the proper AF adjustment... and I settled on about +15 at 24mm! That is huge. At that setting things looked pretty good when autofocusing around my office though.
However, using this setting I then tried 70mm... and it back-focuses. Not a huge amount, but it is evident. Then I try ~40mm... and now the DoF at 40mm _totally_ misses the target... back focusing beyond the target. Craps.
I believe that something is actually wrong with the lens. This isn't a tolerance thing. I think that an element must be de-centered or something along those lines (de-centering would explain the lack of sharpness on one side of the image as well).
I'm not going to mess with Nikon on this one. This is a $2000 purchase that is less than 2 weeks old. I think it's going back to the reseller for replacement on Monday. I bought it online... now I'm wishing I hadn't (much easier to take it back to my local shop...)
What would you guys do?