Nikon 135mm DC very soft at f/2 but sharp at f/2.8 -- did I buy a bum lens?

[Rajah Sulayman]

After much searching, I managed to find the coveted Nikon 135mm DC lens on Craigslist. I immediately slapped it on my d700 and took it for a spin, and found that shots at f/2 are incredibly soft when shot at f/2 but tack sharp at f/2.8. From what I'd read, this lens should be sharp at any aperture, and while I understand that a lens' optimum aperture is usually one or two full stops down from wide open, I kind of expected better performance than this.



The second shot is slightly more underexposed than the first, but that shouldn't make much of a difference. Focus point in red, but it's largely academic; the softness is abundantly clear even if you didn't know what I was focusing on. Shot hand-held but braced. DC is set to 0 on both shots, which should rule out defocus issues.

Is this expected performance, or did I buy a bum lens?

[OsmosisStudios]

That is ludicrous. I'd be sending it into Nikon.

[sk66]

Actually, getting a better exposure at f/2 will make a pretty large difference, it's "washed out"... and there is a certain amount of "relativity" to "sharp"...

All I did was adjust the exposure and contrast in the upper half....it looks much better and I'd call that pretty sharp for wide open at f/2, 100% crop. It would probably be better if it started out better exposed.

[Rajah Sulayman]

Originally Posted by sk66

Actually, getting a better exposure at f/2 will make a pretty large difference, it's "washed out"... and there is a certain amount of "relativity" to "sharp"...

All I did was adjust the exposure and contrast in the upper half....it looks much better and I'd call that pretty sharp for wide open at f/2, 100% crop. It would probably be better if it started out better exposed.

You're right that the term "sharp" is relative. After doing more test shots, it's not so much that it's out of focus as just really low-contrast.

Here's another shot I took, this one of my roommate. Both shots were 1/250 @ ISO 200, using my sb-900 for light. Only difference between the shots at all is that the top one was 2.8 and the bottom one was 2. The difference is pretty dramatic.

[sk66]

A little contrast is going to be sacrificed at wide open, but I wonder if the Defocus Control isn't completely nulled out at the Zero Setting (it is at the zero setting right?). The defocus function tends to cut contrast some which is generally a good thing for portraits.

[sk66]

Now that I can see the pic, I'd guess it's not the defocus... Defocus is only supposed to affect that which is already out of focus (and somewhat the edges/contrast)
If you bought it new it wouldn't hurt to try another one...I'm not sure I'd be thrilled with that performance for the price.