Monday, May 10, 2010

Fixing Broken Plastic Nikon F-Mounts

There are more than a couple Nikkor lenses out there that for some reason Nikon decided to use a plastic lens mount instead of a metal mount. Models include the 18-55 DX and 55-200 DX in both non-VR and VR variants. It doesn't take much more than an accidental drop or knock and the plastic tabs will break off and the lens wont be able to mount to the camera body. Luckily this is pretty easy to fix. Searching around after doing this I found similar repair guides written up here and here.

I should make a short disclaimer that performing this kind of minor surgery on your lens yourself will most likely result in any warranty you once had to be void. In addition, any damage you my cause is not my responsibility. You should take due caution to be careful to not damage your lens including covering the glass lens elements as needed.

So Here Goes

What you will need:

Spare Part
: I gave the Nikon Parts Department a call (number is at the bottom of the link btw). A friendly Nikon service rep answered the call and helped me. A few days later my part arrived at my door stop. $15 all up.

Tools: #0 and #00 Phillips head screwdriver. If you dont have these, a precision screwdriver set is readily available from Amazon for less than $10.

Optional: Second set of hands will prove helpful for the reassembly process.

The replacement F-mount is a plastic unit, just like the broken one. It has an attached cable and a thin piece of plastic that protrudes out for a few cm, make sure you note where that plastic comes from when you remove the old bayonet mount.

Figure 1. Nikon 1C999-601-2 replacement plastic bayonet mount.

Place the lens with the mount pointing up. Looking at the F-mount, you will see 3 large screws (all three visible in Figure 2). I used my #0 Philips head to remove them. I put them on a piece of paper and labeled them to make sure I remembered where they came from.

Figure 2. The old lens mount with broken tabs.

Next its time to remove the screws from the collar. Note there are two sizes here (Figure 3). I removed the medium screws with a #0 and the smaller with a #00 Philips head. Again, separating them on a labeled piece of paper makes reassembly that much easier. Admittedly if you it wouldn't be too hard to figure out where they go if you did mix them up.

Figure 3. Screws on the collar. From memory there were two medium and 3 small screws.

Now its time for the fun part. Using gentle force you can remove the center most ring. Next the tab that houses the electric contacts can be removed. It's attached to a ribbon cable so all you need to do is gently lift and remove. The tension of the cable will pull the piece downward. Let it rest inside the lens. Next is time to remove the plastic bayonet mount. This piece is attached to a small cable you will need to unscrew (#00 Philips screwdriver).

Figure 4. Removal of the plastic bayonet mount.

Unscrew the cable from the old bayonet lens mount and attach it to the replacement unit. I found that juggling the small cable (which is spring loaded), holding the bayonet and screw driver easier with a second set of hands. No doubt you could do it on your own though...

Figure 5. Transplanting the internal cable from the old mount to the new. Kudos to my mate Kevin for being the extra hands.

Once done, the new bayonet can be put in its new home. Make sure to line everything up and pay special attention to the two metal shims under the bayonet which may have moved during the surgery. They can only go one way. I used my small screwdriver to help line everything up.

Figure 6. Lining up the shims before putting the bayonet in its new home.

Once that's done, screw it in place with the large screws. Next, the tab holding the electircal contacts can be gently lifted back in place. It should lock into it's home position. The final piece to go back on the lens is the center ring. There are two ways to put this back on. First method is to put the ring back in place and use a screwdriver to push the aperture controlling tab into position (Figure 7).

Figure 7. Moving the aperture control tab with a screwdriver.

The second method is easier. Simply use the gap made for the tab on the center ring to push the aperture control tab forward as you slide and push down the whole center ring down, locking it into place. It is much easier to do, than it is for me to explain. I think Figure 8 shows the process reasonably well.

Figure 8. Second method for putting the center ring back in place.

All you need to do now is put all the screws back into the lens and you have successfully repaired your lens. After I was finished I noticed that a stray finger had made its way onto the rear glass element. A quick brush and polish with a lens pen will take care of this.

Figure 9. Finish up the repair with a good cleaning.

Put it back on your Nikon SLR camera body and enjoy the fruits of your labor!


Anonymous said...

Thanks found your link. As someone is selling a 55-200vr for $70 that they say it mounts and works great but the bottom doesn't stay tight and locked. Sounds like a broken mount.

Tempted to buy as on very limited funds and can order the mount and still save about $40-$50.

Nate said...

If it is the case and the mount is broken, you can fix it yourself, no problems. I would definitely recommend having a second set of hands as it makes the repair a little easier. Good luck!

Ryan said...

You obviously didn't have any problems with your repair, but I was wondering if you had any thoughts about focusing no longer working after attempting this repair. My wife and I did it, and had a couple hiccups that could have broken it worse than it was before, but after getting it all back together, it mounts fine but is completely incapable of focusing in manual or automatic. Just wondering if you had any additional knowledge on the topic or any troubleshooting suggestions.

Nate said...

Hi Ryan,
I am really sorry to hear that your focus is not working now. I am obviously not an expert in lens repair, but I will try to help you. One question, did your broken bayonet have a wire attached to it? If so, did you transfer it successfully to the new bayonet? Also, I wonder if the ribbon cable that connected to the electronic contacts (i.e. the ones in the top left of Fig. 3) are loose, or if the electrical contacts themselves are dirty?

I hope this helps some. Also, if you have the 18-55 you can find some manuals here:

I hope this helps, I will look for some more info...

Ryan said...

I realize you aren't an expert, there's just not a whole lot of information out there for self-repairing lenses, and like most people I figured the lens was cheap enough to be worth attempting the repair myself, and don't know where we ran into a problem. The broken bayonet did have a wire attached and it was a pretty easy transfer, but I'll look at it more tomorrow. I do have the 18-55 VR, and I'll definitely look through the manuals and do a little more trouble shooting myself. I appreciate your quick reply and will be checking back to see if you stumble upon any more useful info.

Steph T said...

Thank you for posting this great tutorial! I was able to successfully fix my lens today in about 20 min. :) I am SO relieved to be able to use it again. It was well worth fixing. I wonder if Ryan ever got his lens focus working again? When I took my old mount off I did not pay close enough attention to where the long plastic piece came from. When I went to put the new mount on, I made a guess that it should be to the left side (from the perspective of the outside of the lens) of a spring-loaded piece with a tiny screw sticking out--in such a way that when the lens barrel is manually rotated, this screw glides along the long plastic piece of the lens mount and can be seen by peering into the lens. If the plastic piece is not in the right place, my guess is that the lens would be unable to focus at all.

Nate said...

You're welcome Steph, I am glad this helped you out. I know the piece you are talking about and to be honest, I'd have to pull a lens apart to see what it does but I think you are right in that it wouldn't function correctly if it were miss-placed.
Happy shooting!

//Harri said...

Thanks, waiting for a new mount, have removed the broken one before I found this guide. :)

Nate said...

Good luck with the repair Harri! The repair is pretty straight forward, hope all goes well.

//Harri said...

Thank you! Received the part today, made a attempt to exchange the part during my lunch break but that was a bit too optimistic. ;)

But just a moments ago this evening I finished the "operation" and the lens works perfectly again!

Just a pointer, even if it's quite obvious, the two smaller screws with fine threads fits where one can see some metal on the inside, on both sides of the electric contacts, whereas the three larger screws holds the center ring.

I forgot to note where they where located and it was a while ago I removed them. =)

Pat Richard said...

Thanks very much for your post...I do abit of work with Student Journalists at St. Thomas University here in Fredericton NB Canada...and I was able to put this little lens back in service following your instructions(and take my lens own home!). Thanks again!

Nate said...

Awesome Pat, I am glad it helped you. Nothing like fixing it your self and saving a few bucks along the way!

Nate said...

What would you suggest I do if I was stupid and disconnected the wire connecting the small gold piece of the mount to the lens? Solder?

If so, what kind of solder? (I'm REALLY not an expert as far as soldering goes)

Thank you! :)

Nate said...

Did you unscrew it or pull it from the solder? Or even cut it? Obviously if you unscrewed it, you need to re-attach//screw it back on. Otherwise you will need to solder it on. You'll need some solder and a soldering iron with a finer tip. Your local Radio Shack should have both of these. If you need some new wire, RS should also have some fine gauge wire as well as wire cutters (get the ones that strip many different wire gauges).

As for soldering, I learned from some of the many excellent tutorials from the internet. I'd recommend doing the same.

maf_groupp said...

my nikkor 18-105mm boyanet mount unit is broken so i want to ask your opinion whether i can change it with the nikkor 18-55mm boyanet mount unit.

Nate said...

I think you probably would be better served getting the mount for your lens. Easy way to answer your question, since I am not 100% sure is, call the Nikon service department, and ask. I am sure they would be able to tell you if the two lenses use the same part number. Let us know how it goes!

Quique Garcia said...

Hi, i'm from spain and my "plastic ring fake" it's broken, but Finicon (service of nikon in this country) not sold this piece beacuse it's best win 130€ for the fu*** repair, you know some site to buy? or some caritative soul can buy to me.
And of course, sorry for my english ;)

Anieztacia Touch & Collection said...

how about nikon 18-105mm?

Anieztacia Touch & Collection said...

i broke my nikon 18-105mm.can i use the same product i mean Nikon 1C999-601-2 replacement plastic bayonet mount?or must use specific mount?

Anonymous said...

You can buy it on Ebay

Anonymous said...

I was able to get a replacement bayonet for my Nikkor 18-105mm lens from (they accept paypal). the part arrived within days. only problem I had with my repair is that once I got the lens unassembled I realized my collar was also in need of replacement so I'm waiting on that part to arrive so I can proceed. I also managed to somehow pull the wire loose (I guess it's for the autofocus?) so looks like i'll be trying to learn to solder as well.

Anonymous said...

As for the mount ring being plastic, I would say this is a good thing. Why? Cost. If it were steel or something similarly sturdy and the person dropped the unit, there is a very good chance that it would ruin the mount on the camera body, which is much more costly to repair than a plastic ring. I think Nikon made the right design compromise here.

Anonymous said...

When I get to the point of attaching the new bayonet am I to remove the new cable from the new part and attach the old one?
It doesn't seem to have much room to give and I'm afraid if I pull on it too hard the wire will detach from the spring. If it does detach can I solder the wires together or must I remove the wire from the new one and solder it directly to the spring?

Anonymous said...

what is the function of the wire? It is in there pretty snug and I don't want ot pull too hard. If it separates from the spring can you solder the old wire to the new wire to make it longer or is it best to just solder the old wire onto it directly?

Nate said...

Yes, remove the wire from the new bayonet and attach the old one. Be careful and methodical and you will be fine! Good luck.

Anonymous said...

I've repaired a few of these, the four lenses using the plastic mount are the 18-55,both VR and non-VR versions, 18-105, both versions, 55-200 both versions and the 18-135. To keep track of the screws, I use a length of bluetack on the desk to stick them in, in the order they come out. I also wrap some sellotape round the body of the lens, so that nothing else comes loose once the back mount is removed.
I personally found it easier to unscrew the wire and spring loaded stud from the ring mount, change the mount over and then reattach the stud later. A very small flat head precision screwdriver to unhook the spring and then reattach to the new mount (all makes sense when you're looking at it!), and then reattach the wire/sprung stud. Also make sure the stud does actually protrude through the new plastic mount and come out slightly on the camera side of the lens, or it will not talk to the camera. I repaired one on an 18-105 a month ago, where I could NOT get the stud to go all the way through, and just could not see what i was doing wrong, in desperation I cut off very small pieces of solder, dropped them in the slight depression where the stud had come half way through and then melted them with the tip of the soldering iron to make a connection all the way through!

I have found the same generic plastic mount works for the 18-55, 18-105 and 55-200 (not tried on an 18-135 yet), if you remove the mount from the metal ring that sits inside it with the metal bar that goes down inside the body of the lens, so that part does not change, I have had no problems so far.

I have repaired two, a 55-200 and an 18-55 VR, where the manual focus did not work after repair - I notice this was an issue for someone. Not too sure why it happened, those repairs did not seem any more troublesome than the others. I have bought a couple of lenses with autofocus/manual focus issues from eBay, after some fiddling with them, I'll post any useful findings on here. I'm no genius, all the tips above are learnt the hard way through trial and error, make of them what you will. If anyone wants any further help, email me on nick2491 at sky dot com

Anonymous said...

Thank you for this information, I have used it successfully to repair an 18 55 G mk2 non vr.

I used a non genuine mount off ebay which cost £3.50 gbp delivered, its naked i.e. you have to swap both the earth contact and the appature bar/spring bit over, and there are slight cosmetic differences to the molding, but very cheep so I thought it was worth a shot.

All went smoothly, apart from 1 small snagging point in getting the right side screw to the contacts block to bite when re-assembling, eventually with plenty of patience I got it, but I thought I'd let people know, be carefull the screw goes in straight 1st time, cos 2nd time is much harder!

The lens apears to function perfectly now, Thanks again,

Anonymous said...

I just called Nikon and the support guy said they don't sell the part. :(
I need to ship the len to them to fix.
I have the AF-S Nikkor 18-55mm VR DX and wonder the pn is IC999-601-2 and try find it from google.

Mario Alvarez said...

What is the small wire for?

I broke it on a AF-S 18-105mm VR
The ring I bought came without a wire.
I put it all back together without the wire and it seems to work ok.
If is important I'd like to fix it.

Christin Love said...

I have read through some of the other comments. I accidentally broke the soldered connection on the tiny wire. Some people have said that their lens still works with the wire disconnected so i put everything back together and when i look through the lens everything is really dark and I can't get it to take a picture. Any thoughts on what could be causing this? Should I attempt to solder the wire back on?

Anonymous said...

I too broke the solder despite being as careful as possible! USE A SECOND PAIR OF HANDS no matter how clever you think you are, because it's surprisingly easy to do. And find a soldering pen in Mexico...

Anonymous said...

I dropped my D90 from 1-2 feet and broke one of the three bayonet mounts on the ring. A replacement mount cost me $7 on ebay and using this guide I replaced it in half an hour.


Juan Carlos Posada said...

What happens if I broke the cable? Thanks!

Juan Carlos Posada said...

What happen if i broke the soldered cable???

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