I have the DA 18-135. It's been a fine lens. I've lived with the edge softness (which is not due to decentering). For the shooting I do, I wanted something a little wider and a little better quality. The DA 16-85 is the obvious choice. I can't afford a new one, but I found a used one on Amazon. Externally it's perfect, and the glass is spotless.
I'm putting it through its paces, since I do have a 30-day return policy. First impressions:
- I really like the extra 16mm at the wide end.
- It is a higher quality lens than the 18-135, and it isn't that much bigger.
- The center is definitely sharper, and the edges are much better for the most part, but...
The lens clearly has a little bit of a decentering issue.
At the 16mm end, the effect can be reduced by closing down. Here is a shot at f7.1. The cedar trees were on the left and right edges of the shot. You should be able to see that the right side is softer.
The decentering is a bit less noticeable as I zoom. Not much to speak of in the 35-60mm range. At 85mm, the softness has moved to the left side, though it is not as pronounced.
For comparison, I took the same shot with the 18-135mm at 18mm and moved back just a bit to get the same field of view. You should be able to see that the 16-85 on the left is a bit softer than the 18-135 on the right, both showing the same right side of the pic. (The 16-85 is superior to the 18-135 everywhere else in the picture.)
Now I realize there really isn't a perfect lens. There will always be some edge softness. The softness varies with aperture and with zoom. There is always some compromise that is made.
I'm trying to decide whether to return/exchange the lens. I got it for a good price, and, as noted, externally it's in perfect condition. There is also no guarantee that I will get a better lens. (
Tibbets went through 5 copies of the 16-85 to get one he was satisfied with!)
So, how much decentering is too much? Is it just a matter of deciding what one can live with, balancing out the lens quality and price, etc.? I'm inclined to keep the lens, since I don't know about getting a better one at the same price, but I'd appreciate hearing how others decide whether to return/exchange a lens or not. Thanks!