J W 
, Jan 29, 2010; 09:38 p.m.
I shot both of these photos with my D300 with the 18-200 Nikon lens at 26mm - f/4.5. I tried AF fine tuning on them.
In this first picture (AF tune @ +10) the image is clear towards the right-center but blurry on the left.
Strangely, with AF tune @ -5, the clarity is reversed from the above picture. It is now clearer on the left and more blurry towards the right-center. Can anyone figure what's going on? The subjects are far enough away where depth of field should not be an issue.
Robert Hooper 
, Jan 29, 2010; 09:46 p.m.
Where is the point of focus? What was your shutter speed? Solid tripod? Exposure delay mode, (mirror up)? Also, I would have stopped down further than f4.5 to take this image.
J W , Jan 29, 2010; 09:50 p.m.
I focused on the bright building near the center. The buildings are all a few hundred feet away and shot wide angle, so depth of field should be infinite. I wanted to shoot close to wide open in order to tune my lens.
Howard Vrankin 
, Jan 29, 2010; 09:51 p.m.
Were you shooting these obliquely through a window pane?
J W , Jan 29, 2010; 09:52 p.m.
No, there were shot outdoors on my balcony on a tripod.
Robert Hooper , Jan 29, 2010; 09:54 p.m.
Hi Paul,
You probably should use a different test subject under better lighting conditions to tune your lens. Sorry I'm not more help. I'm sure someone else will chime in soon.
Robert Hooper , Jan 29, 2010; 10:05 p.m.
Oh yes, and be sure VR is off when using the tripod.
J W , Jan 29, 2010; 10:08 p.m.
Stephen Worth , Jan 29, 2010; 10:45 p.m.
The two look pretty much the same to me. The one on the left has a little more coma than the other, but if you look down in the right bottom corner of the sample, they look pretty much the same. The slight variation between them is probably wind or heat rising between you and the bright pinpoint lights.
Robert Hooper , Jan 29, 2010; 11:03 p.m.
Good observations, Stephen. There are a lot of possible variables here. Another is the stability of the balcony Paul shot these images from. I live in a 40 floor condominium here in Honolulu and while standing on my 7th floor balcony in my bare feet, I can feel periodic vibrations through my concrete deck. I live close to a freeway and three elevators are constantly traveling up and down within the building.
Also, I would be interested in seeing an enlargement of a similar area on the right edge. I am still bothered by this image being shot wide open and the resulting loss of edge sharpness at this magnification.
