Nikkor 17-55 2.8 recently fuzzy and extremely soft, when wide open

<p>Hello,<br>

i'm experiencing some issues with my 3 year old Nikkor 17-55 2.8 lens, which has been performing excellently until about half a year ago. It recently developed a set of problems, including a fungus (am living in the tropics), a strange aperture control issue (for which there is a work around) and this image problem.<br>

Wide open then lens shows a severe blur across all areas of the picture, when focussing at distant objects. With apertures > 5.0 this is decreasing. This does not occur with any of my other lenses on my D7000 camera body.<br>

I've had the fungus removed at a repair center and have also sent the lens for calibration/checking to the local Nikon center in Bangkok. It came recently back from the center with out any comment on the lens issue and with no improvement whatsoever. I understand that fungus can etch the lens surface and cause irreparable damage, however, I'd love to hear from some other people if the issue could be caused by that or if the local Nikon center just didn't check the lens properly. It seems odd that they didn't comment on the issue at all, given that it's rather apparent. Below are a few pictures showing the issue and a comparison picture with an old prime lens.<br>

Please also note that the issue does not seem visible through the viewfinder, which displays everything crisp and sharp.<br>

Thanks for your help<br>

Picture at 2.8 with clearly visible issue:<br>

<a href="http://1drv.ms/1bIRJKk">http://1drv.ms/1bIRJKk</a><br>

Picture at 5.0 with less issues but still visible:<br>

<a href="http://1drv.ms/1PcmR7J">http://1drv.ms/1PcmR7J</a></p>

<p>I would suspect that the fungus went beyond just being on the glass and also got into the mechanics or electronics of the lens.</p>

<p>The 17-55 Nikkor has field curvature; at the shortest focal lengths this becomes very obvious at long distances. You may want to optimize the focus using live view considering the entire image field and stop down. </p>

<p>Thanks, this issue is not related to geometric aberrations. The linked pictures are shot at about 50mm.<br>

As for the invasive fungus, yes, this may be true, however, I don't quite understand how this would cause such problem as focus and aperture work fine. Initially I've thought this would be a misaligned lens element, but since Nikon Bangkok didn't comment on this at all, I'm a bit confused. Apparently Nikon adjusted the focus - well, the focus wasn't the issue then (or at least not the primary one) and the lens still has the same problem... <br>

Any more thoughts anyone?</p>

 

<p>I have used a Componon-S lens plenty of fungus and results were sharp. To perform this way I think the lens should have loads of haze. Does the lenses look clear or hazy?<br>

What Ilkka says... if you test it using Live View, do you get the same blur?</p>

 

<p>What Jose says. Then, if the Live View is ok, I'd check the af fine tune value for that lens.<br>

"Distant objects" - that could point to a loose or shifted lens element -optics or something with mechanical focusing system. Can you get the focus both with Live View and by focusing manually?</p>

<p>Did you have the lens mount--both on the lens and on the camera checked for squareness?</p>

<p>The 17-55 is fairly sharp wide open. No lens is "perfect" wide open, and sharpness is only one measurement of many as to what constitutes a good image. But it sounds here as though you have multiple issues. </p>

<p>AFAIK, 'fungus' is a complex, destructive little bugger but confines its diet to the organic debris inside your lens. It's biological byproducts damage lens coatings but not much else. Certainly not enough to have any mechanical effect.</p>

<p>You should be able to see it by shining a torch down inside, any spider-web like trails on the elements will be clearly visible. It has to have <em>serious</em> fungus to make it's presence known optically, and usually shows up as a loss of contrast, not big blurry areas.</p>

<p>Thank you all for the comments. I would have thought the same, that fungus would unlikely cause mechanical problems but rather degradations of the lens coatings. The inner lenses are spotless after the fungus removal and there is no trace of spider-web like trails or anything like that. Also the aperture blades move smoothly and easily, and I've checked the lens mount for damage, but it looks almost new.<br>

Re live view, it's hard to tell on the relatively small screen and I would have said the problem does not show up there - however, I took a video with both my 50mm prime lens and the 17-55mm lens and there clearly is a blurriness across the whole picture in the latter. I would assume that video and live-view picture are the same in that regard?<br>

Taking a picture of a closer object also shows that this isn't a misaligned focus point, as there simply isn't any spot from near to far that's focussed.<br>

I guess there's no way to identify the real problem further - frustratingly the Nikon center didn't even pick up on the issue, so there goes my confidence in getting this fixed through them. I might look for an independent camera shop enthusiast that has some mechanical skills or the right instruments to diagnose this...not much to lose, is there.<br>

Again, thanks for your thoughts and if anyone does have any further suggestions to test this, please comment.</p>

<p>Jan, you have <strong>to take a photo</strong> using the "Live View" system... it means to manually focus using the camera back screen.<br /> The image at the back screen can be magnified/brightened for the highest accuracy while focusing. Carefully read your user` manual for more details.<br /> You must do it this way to discard alignment problems. If the image came out sharp, you will know that is a focus issue (AF problems, wrong settings or whatever). If the image still came out blurred, you´ll know that is an alignment issue or something more complex that need to be serviced. <br /> I assume your settings are right and the Nikon repair center missed a complete check after charging your account (something quite common around here, I guess).</p>

<p>I'd compare images before and after the fungus removal. It is possible that something got out of specifications during that process. The lens has a quite complex construction and if it was totally disassembled for cleaning...</p>

<p>Just one possible explanation more.</p>

<p>@ Jose Angel: Thanks for the clarification on this. I hardly ever use the live view, so, embarrassingly, I wasn't aware of the magnify options on the screen. Good to learn something new and useful. I've done this now and can confirm that live view clearly shows the same as the resulting picture: a blur across the whole picture. Clearly not a focusing issue. Very helpful suggestion this test and I'm better armed to discuss this again with the Nikon guys.<br>

<br />@Kari: Yes, good point and I forgot to say this in my initial post: This issue was apparent before the fungus cleaning. In fact this was the primary reason I brought it in for checking. The removal of the fungus did neither worsen nor better the issue.</p>