Update on D7000 issue - and a lens dilemma

[michael_b10]

<p>Thought I'd write to update what I've learned about the issue I raised a couple of weeks ago about my D7000 with focusing issues on zoom lenses that work well with my D90. The problem I mentioned was pronounced backfocus at wide angles with two different copies of the 18-70mm Nikkor zoom when paired with my D7000, and I was seeking opinions as to whether it seemed more likely that it was an issue with the lenses (as Nikon suggested it might be) or with the D7000 body. It seemed unlikely to me that two lenses would have the same problem. Well, I finally got my hands on another zoom - a friend's 18-105mm kit lens. To my amazement, the focus issue didn't exist with this lens. Even shooting wide open at wide angles, the images were perfectly focused and remarkably sharp. So - I have no idea why my 18-70 lenses work so much better on my D90 than on my D7000 - but at this point I'm pretty convinced that there's some issue either with the lenses themselves or the way they communicate with the body -- but not with the AF accuracy of the body itself. </p>

<p>So that's a big relief! But now, obviously, I'm convinced I need some new glass for my all-purpose walkaround. My ideal lens would be an 18-70mm f2.8, which of course doesn't exist. I've narrowed down my best options to either the Nikkor 16-85mm or the Sigma 17-70 f2.8-4 os, since both cover the range I really need. Does anyone have experience with the Sigma on a D7000? Any idea how it compares to the Nikkor in practical usage and overall IQ? (Tempting as it is, the Nikkor 24-70 f2.8 isn't an option - it's just not wide enough on DX for me as a walkaround. And the 17-55mm isn't long enough.) thanks for any input!</p>

 

[andylynn]

<p>I have experiences with both those lenses on a D90 but not a D7000. On a D90 they're both quite good. Image quality is indistinguishable.</p>

[lenk]

<p>I highly recommend you do a micro-focus adjustment with each lens on your D7000 body <strong>before</strong> you replace those lenses. You may find that resolves your back focusing problem.</p>

[michael_b10]

<p>Thanks for the input. I have done micro-adjustments, and it helps alot. But one of the 18-70s has developed another problem, probably due to age/abuse; and the other really belongs to my girlfriend, so I could probably hijack it from her but.....</p>

[ronald_rogers1]

<p>This is very interesting. I also have an 18-70 Nikkor and have had similar problems. I am going to trying using my manual 50mm 1.4 just to see if there are any differences in sharpness. I realize its apples and oranges, but am curious to see what differences there may be when I A-B them.</p>

[ShunCheung]

<p>The 18-70 DX has some drawbacks, such as weird distortion and some vignetting issues, but sharpness should be good. We know that the D7000 is demanding, but I took would check the lens out thoroughly first. AF fine tune should help. You can also test it using live view to tune focus while putting the camera on a tripod.</p>

[michael_b10]

<p>Ronald - my prime lenses, including an 50mm 1.4D, focus perfectly on the D7000. It's the 18-70 that's been really weird. Both of them. The most bizarre thing is that the backfocus issue goes from being noticeable but not horrible when using the center focal point to being radically bad when using a focus point near the side of the frame. But only when shooting wide. Didn't have this problem at all when using my friend's 18-105 kit lens. And, yes, when shooting at longer focal lengths, and stopped down a little, my 18-70 is incredibly sharp.</p>

[breogan_gomez]

<p>I have used the Nikon 18-70 and the Tamron 17-50 before I ended in the Nikon 17-55 f/2.8. The 17-55 offers truly great picture quality in sharpness and color saturation.</p>

<p>Moreso the 17-55 is build like a tank which makes you feel your money has gone to something that will last to your children. The 18-70 and the Tamron are made of plastic and have many moving parts that are prone to woble.</p>

<p>You can use your 18-70 to see the real world difference between 55 and 70.</p>

<p> </p>

[stefan_g]

<p>Can the opening (effective f-stop) the D7000 uses for autofocus be changed? Back when my D70 was new we had a discussion here on back focus. Somebody pointed out the different effective f-stops used for what you see in the view finder versus the CCD (=final picture) versus what the autofocus mechanism sees and how this can have a negative effect if a lens has focal length varying with radial zone. If I remember correctly, it was mentioned that some of the higher end Nikons allowed switching of the effective f-stop used for autofocus.</p>

[John D]

<p>Regarding the Sigma lens, I have the older one which winds up at 4.5 on the long end. I bought it to haul off on a European Cruise with a D300. I was not interested in the macro capability but I wanted something which did not break the bank and also did not wind up at 5.6 on the long end. The lens was and is a decent performer for me. I had previously had the 17-55 f2.8 but had sold it with my D2x. I am now using the 17-70 on my D7000 and am happy enough with it that it is still there. I have found nothing which would do what I want a general purpose lens to do which would replace it. Would I like a bit more reach, of course, and a bit wider too but we have to make compromises. I would jump on the 16-85 if it wasn't 5.6 on the long end and 3.5 to start with. Is the 17-55 better, undoubtedly, but it lacks reach. I have paired the Sigma with another Sigma, the 10-20 for my D7000 go anywhere kit. If I need more reach I either use my 180 2.8 or the 150 Sigma which also gives great macro. Given all that I would sure try bfore buy if I could.</p>

[tim_eastman]

<p>There seems to be a common thread to focus issues with the D7000; zooms that focused well with previous Nikon bodies but don't with the D7000. When I took my D7000 to my LCS, where I bought it, and told them of the problem, they told me they had not seen this problem, but now it seems that they have sent three other D7000's back for adjustment. I never had a focusing problem with my 18-200 on my D80 or D300. I think the biggest problem is my lack of confidence in my D7000. I sure hope the problem is fixed, but wondering if images will be in focus makes me uneasy. I already have many images from a trip to Italy that were out of focus.</p>