Wobbly 20mm

[jay_chadney]

I have a line on a good deal for the af 2.8, but the front element is loose. Thoughts on cost to fix?

[ShunCheung]

<p>Buying someone else's problem is most likely not exactly a good deal.</p>

<p>Are we talking about a manual-focus AI/AI-S lens or AF/AF-D? Once upon a time, the aperture diaphragm on my 20mm/2.8 AF got stuck. Nikon USA charged me over $200 to replace it; that was around 1999/2000. Eventually I sold that lens for not that much more than the repair cost.</p>

<p>I would suggest getting one that is in good condition to begin with.</p>

[tony_defilippo1]

<p>Where do you live? Here in the DC area I've had some CLA type service that didn't require significant parts as cheap as $100 but I've had a front element replaced (on the first edition 24-120) years ago that was around $200. </p>

<p>Unless you are getting a screaming deal on the 20/2.8 I wouldn't touch it. On KEH right now you can get a 'Bargain' condition one for $339. I'd assume a minimum $150 for the service (if it can be fixed), so unless you get the lens for under $150 it looks like a bad idea and even if it was that cheap its still a roll of the dice!</p>

<p>*I did roll the dice on a $25 35/1.4 Ai-S one time and was pretty darn happy after it was fixed for $140! </p>

[bruce_rubenstein]

<p>There is typically a threaded retaining ring that holds the front element/group in place. They can loosen up over time due to things like vibration. To tighten things up the trim ring has to be removed and then the retaining ring has to tightened. There's no alignment effected by tightening it back up. If one has the right tools it only takes a couple of minutes to fix.</p>

<p>If you know someone local who can check it out, and probably fix it at the same time, then it may very well be worth getting. If you can't get the right to return it, if you send it out to get a repair/estimate, then it can be quite risky. This lens would be a good deal for someone it can tell what's wrong and fix it themselves.</p>

[borgis_karl_johan1]

<p>As I have written before, I have owned two manual f2,8 AIS 20mm lenses, one bought in 1984 and the other one probably in the early nineties. In both of them the front CRC unit speedily worked itself loose- the first lens was brand new, the other one visually unused.<br>

This must be a construction glitch of the AIS version rather than an effect of long-time wear and tear. Nikon Germany´s service at the time was hard pressed to recognize the problem, the ´84 vintage lens was sent back to me as "no defect" after an -apparently- sloppy inspection.<br>

Optically I prefer the older, tiny f4,0 lens.</p>

[fred_mackintosh]

<p>At least the AI-S lens seems to suffer from a design/construction glitch. I have also had a loose element, but "fixed" it myself, and am happy with the lens. </p>

<p>I have actually had 3 of the 20/2.8 lenses over the years. After my first AI-S one from the 80's was stolen in the 90's, I decided about three years ago to buy a new AI-S one again. I very much liked my original one. They are still available, along with the newer AF-D version. This second AI-S of mine is from a late serial number block (3...) indicating post 2006 manufacture (details can be found on Roland Vink's site: http://www.photosynthesis.co.nz/nikon/serialno.html). I purchased it at B&H. </p>

<p>I noticed immediately that it had a significant rattle. I also immediately noticed that it was a very poor performer on my D200. I identified that the front element was loose! (Again, this was straight out of the box, purchased new.) I was quite disappointed, but somehow never got around to taking it back to B&H or at least contacting them. (I am sure they would have taken it back or replaced. I have never had a real problem in dealing with B&H over the years.) But, for whatever reason, I just never did anything about it. I tightened the front element carefully myself, and noticed it performed well on film bodies (not quite at the level of my Zeiss 21 for G-series...). Once I got a D700, I also discovered the lens worked well on FX. I even found that it worked well on D300s/DX. Not sure what the problem was with my D200, but the lens just never sharpened up on that body, and it was uneven right to left. </p>

<p>Anyway, as strange as it may have seemed to have a loose front element on a new lens, by just tightening it myself, I found that I have an excellent lens. I even later compared it with a Zeiss ZF 21/2.8 that I got a great deal on. The Nikon is not as good, but for the size and price is still an excellent lens. Stopped down to 5.6-8, there is little difference between the two on FX/film. Given the extreme vignetting of the ZF at 2.8, the advantage of the ZF at 2.8-4.0 is usually not worth the size and weight. Anyway, after being initially very disappointed with my 20/2.8 AI-S, I eventually developed a lot of respect for it. So much so that I eventually decided to get an AF-D one (used in good shape), just for the chip (e.g., on F5 and F80s). To my disappointment again, the AF-D one rattles like crazy. The whole front section of the AF assembly wobbles! This time, it is not the front optical element that moves. Again, I felt like sending it back. But, surprisingly, it preforms at the same level as the AI-S. In fact, it seems to marginally outperform the AI-S in the 4.0-5.6 range. One thing I have noticed, however, is that it is definitely better to manually focus the AF-D than trust the AF. With careful focus at mid apertures, it performs very well. With AF, it is not so reliable. </p>

<p>So, wobbles and all, I still find the 20/2.8 Nikons to be excellent lenses, especially when one considers their size. One can see why they were so valued/popular in their day. I have not tried the small 4.0 version, but the 3.5 AI-S that the 2.8 replaced is a poor performer, by comparison. I just advise you to try to tighten the front element carefully by hand. If that solved the wobble, you will likely be happy with the lens. I wish they had opted for a more robust construction, like most of their other AI/AI-S era lenses. </p>

[borgis_karl_johan1]

<p>Hello Fred,<br>

interesting to hear someone shares the same mixed experience with the 20mm lens.<br>

Well closed down to around f8-f11 I find the f2,8 lens very good indeed, opened up there is less to recommend it.<br>

I found the f3,5 version that I owned for some time a likeable lens, never really sharp though along the edges and in the corners. All in all I prefer the f4,0 version, for its tiny size and excellent performance.</p>

[fred_mackintosh]

<p>Hi Borgis,</p>

<p>I always wanted to try the super-cute little 4.0 version. I have held it in my hands. It really is tiny. Maybe I should. But, I did also try the equally tiny Voigtlander 20/3.5... Not good. About the same as the 3.5 AI-S and more expensive. I was surprised, since I find the 40/2.0 SL-II in nikon mount superb. Anyway, I think between my 21ZF and my two 20/2.8s, I have (more than) enough wide angle, especially in view of the 24/2.8 that I also like very much (better than the 20/2.8). </p>

<p>I have learned with both 20/2.8s (AI-S and AF-D) that you have to be careful with focus in order to get the most out of the lenses. But, side-by side with my Zeiss ZF monster, the 20/2.8 AI-s is a very attractive package when traveling light. </p>