Fixing the Micro-Nikkor 55mm f2.8 Tight Close Focus
I recently bought this lens on eBay for about $125. It arrived in almost pristine condition, but the focusing was very tight; pretty much unusable. I disassembled it twice and the main focus rings operated just fine. Put it back together and it's tight again. It took a bit to discover that there are actually two sets of focusing helicals, one of which is in the lens "cartridge" itself. Fixing this problem is actually pretty easy once you figure it out. If you're reading this, maybe my sweat will help you out a bit.
Pay attention while disassembling the lens. You will need to put it back together!
CAUTION!!: This information deals with the close focus helical gears at the front of this lens. DO NOT disassemble the main focusing barrels (don't even unscrew them). If this is where your problem is, there are other sites out there. Getting the focusing barrels back together once disassembled is a royal bitch. You've been warned. ;)
Start by removing the three screws that hold the lens mount, and then remove the mount.
Then, remove the three screws that hold the lens cartridge to the focusing barrels. Once these screws are removed, you should be able to lift the focusing barrels off the lens cartridge. The cartridge should practically fall out.
Now, remove the three screws that hold the aperture assembly and lens from the top of the cartridge, and lift the aperture assembly off the top of the lens cartridge:
I probably spent an hour on the next part. I thought this would come apart from the front of the lens, but it doesn't. There is a cosmetic ring that just screws off, but you don't really have to remove this. The gold colored ring at the bottom turns to focus the front of the lens. This is the part that is really tight.
To disassemble the front helicals, remove the two screws holding the locking tab, and remove the tab.
The helical gears now just screw apart into three sections. Clean all three gears thoroughly with Isopropyl alcohol and re-grease. I used a lint-free cloth with a bit of alcohol for the cleaning. I think it's best to NOT soak these parts in alcohol because the alcohol could migrate a lot of the gunk to the lens elements. Nyogel 744 was used for the grease. As much as I searched on the web, I was unable to find a "this is the one" grease for this. I bought several tubes of different greases about 10 years ago when I thought camera repair might be a fun hobby, and the Nyogel was from that stock. Back then, I'd written "helicals" on the tube, so I used it. Micro-tools sells "helical grease" if you're in a quandry. It's probably not that critical. So far, so good.
Some notes on reassembly:
As long as you have the lens apart, you might as well clean the internal glass elements that you have access to. This isn't a complete disassembly, so you don't have access to all surfaces, but it's a good idea to make sure that the glass is clean before you put it back together.
Here is a picture of all the parts (except for the screws):
And here is the lens, reassembled and ready to go.
And here's the first picture taken with the now-functioning lens. Pictures of the disassembly were taken with this 60mm 2.8 Micro Nikkor D lens. If you're watching the EXIF data, this was taken before I figred out that I needed to set the non-CPU lens data in the D7000.
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Page last updated 29 April 2011