Nikkor 35mm f/2.8 PC drifts

[craigd]

<p>I recently picked up (inexpensively) an early '70s Nikkor 35mm f/2.8 PC lens (with a metal focusing ring and a chrome knob). The glass is clean and it seems to be in good shape, but not having used one of these before I have one question. When I have the lens turned to shift up or down, if I shift it halfway or so and let go of the knob, the portion of the lens that moves will gradually begin drifting downward. Is this typical behavior for this lens or does it indicate some problem like excessive wear of the shift mechanism? Is there a good way to make it stay where it's put?</p>

[don_cooper]

<p>Many years ago I had one with the same problem. Brought it to a photo expo where the Nikon tech fixed it on the spot, only took a few minutes. Evidently it's an easy fix, but I don't know the procedure. I'd try Nikon even if the lens is out of warranty, they might fix it at no or low cost.</p>

[rodeo_joe1]

<p>Mine stays put, and always has. IIRR there's a small tightening collar next to the shift knob to take up any slack. Adjustment is a bit fiddly, but once done it shouldn't need doing again for - well I adjusted mine when I bought it more than 25 years ago and I haven't needed to touch it since.</p>

[Matthew Currie]

<p>Mine creeps a little too, and has some end play at the knob. The knob has a flush retaining nut with pin spanner holes, and it appears that the only adjustment is probably to loosen that nut, screw the knob down against the bracket to take up play and provide a little drag, and retighten the nut. I haven't yet tried this, because the nut is too tight for any tools I have, I don't use it often, and I keep forgetting to do something about it. But I think you'll find the solution in that knob and nut.</p>

[dennis_george_miller]

<p>I also had this problem with a used (but very clean) sample. I decided to put a very small dent (think I used a sharp chisel) at the innermost sliding area, so that it would rub more and not slide so easily. It worked for me, but I can not suggest you try it as it could injure your lens badly.</p>

[rodeo_joe1]

<p>No need to bash anything! Matthew has described the adjustment in more detail than I did in my first post. The holes in the centre nut are just the right size for the ends of an uncurled paperclip. If it's too tight to undo by hand, then the paperclip can be gripped in some pliers and twisted. Then it's a case of adjusting the relative position of the centre nut and the outer ring of the shift knob in order to get the required stiffness.</p>

<p>Good luck!</p>

[Matthew Currie]

<p>Well, this thread spurred me to finally get around to fixing mine, so I can now report exactly what is required, and how to do this, at least on the old style 35/2.8 PC with metal knob.</p>

<p>The knob has a two-hole spanner nut in its center, which I will try to illustrate below. The relationship between this nut, and the knob, whichis also threaded, determines how much play there is between the knob and the bracket that supports the shifting screw. If you tighten the knob a bit against the bracket, play is taken up and there is a little drag, and the lens operates snugly without creep. </p>

<p>In order to do this job, you need to find, make, steal or otherwise obtain a spanner for this nut. The holes are 5 mm. apart, and very small. Mine was too tight to get away with obvious solutions such as a bent paper clip, the points of fine forceps, or other tools that lay to hand. When you do find a spanner that works (next post will cover this), you will need that spanner, plus a pair of pliers or small vise grips (pad with tape if you're fussy about finish) to hold the knob while you loosen the nut. Loosen the nut counter-clockwise, then screw the knob clockwise tighter against the bracket, and then tighen the nut again against the knob. Voila, the job is done! You may have to work the nut back and forth a bit on the threads to get it to operate smoothly, since it's probably been sitting in one place for 30 years, and it gets stiff.</p>

<p>With the proper tool, this really is a very simple job, and the result is gratifying.</p><div></div>

[Matthew Currie]

<p>Well, in the above picture, blurred as it is (the little Canon digi insisted on focusing on the numbers!) shows the knob, and also the marring that occurred from earlier attempts to do the job with inadequate tools. </p>

<p>What I ended up doing was milling down a small cheap 1/4 inch drive socket. Since the holes are 5 mm apart at the center, I found a 4 mm. socket worked well. You can mill, file, or grind the socket down at the end until you are left with two little posts, which you can then trim to the right fine position and diameter with a little file. The resulting spanner should be stout enough to crack that nut loose. Mine did take a fair amount of force, and made a little audible "crack" when it yielded. The rest of the job was a piece of cake, and my lens now works smoothly but with a little resistance, no creep and no play. </p>

<p> </p><div></div>

[craigd]

<p>Interesting information. Thanks to all. I'll have to look around for a tool such as Matthew describes...</p>