Parts for a Tokina AT-X 28-70mm Nikon mount

I purchased a used Tokina 28-70mm lens for my new-to-me Nikon D700. Very nice lens. However, other than it working fine, the lock for the aperture ring is broken. This is causing the lens to not register with the camera and I get fE.E or some other error. I took the switch off and found that indeed it was now two parts instead of one. It is so small that making a repair might not be possible without a microscope. But it looks like it could be repaired.

I reassembled the switch by placing the locking part where it belongs in one of the grooves on the aperture ring. Then I place the main slider on top of that. I think there is a microswitch in the lens that tells the camera the aperture ring is locked because I do not get any errors now.

So my question is does anyone know where I might be able to find a replacement slider switch for this lens? Like I said, I could probably fix the switch with some strong adhesive, but it would require some really good optics that I do not have.

Any advise is greatly appreciated.

While it's not a solution, if you set the camera to pick up the aperture from the aperture ring rather than setting it from the camera, does that work when the lens is at different apertures? It won't give you program mode or shutter priority, and you won't get fractional f-stops that way, but it might tell you if something else weird is going on.

As chulkim said, I don't believe the lock should have an effect on whether the lens registers as minimum aperture - I believe the location of the aperture follower ring (or the EE post switch on low end bodies) should do that. Although G lenses have a way of indicating they're at minimum aperture electronically (I think), so maybe there's something in the lens protocol that the Tokina could be using strangely? I doubt it, though.

If just being set to minimum aperture works... Masking tape? Good luck!

Before "fixing" (if that is what I might have done) it, I would get different readings.

1. When the lens was first attached and the camera powered on, I would get the fE.E

2. After a power cycle of the camera and turning the aperture ring, it was say f2.8 when the ring was on f22

3. Sometimes it would show "delta" F0-F6

Sometimes, and I know this is not good for either the camera or lens, resetting the lens in the mount while the power is on will fix the issue. All this was before I "fixed" the slide.

Now you guys are probably correct but I find it interesting that once I put the locking part back into the slot it started working. Possibly coincidence. I know when I have an issue is when I turn the camera on the aperture shows f22. And yes, if I program the camera for non-CPU the aperture ring works correctly in manual. Yep, work around I know.

added - with regards to the f22 and slide lock, something has to tell the camera that the lens is in auto mode, yes? I mean, if the lock is not on will the camera function in both modes: auto aperture and manual aperture. How does the camera know that the aperture is at f22? Maybe the AI aperture coupling ring on the body. Did I answer my own question? Haha

with regards to the f22 and slide lock, something has to tell the camera that the lens is in auto mode, yes? I mean, if the lock is not on will the camera function in both modes: auto aperture and manual aperture. How does the camera know that the aperture is at f22? Maybe the AI aperture coupling ring on the body. Did I answer my own question?

Yes, you did. It is a fact that Nikon lenses that have CPUs and aperture rings don't care whether the minimum aperture lock is engaged or not, as long as the lens is in fact at minimum aperture. However, I suppose it is possible that Tokina actually put an electrical contact in that lock-switch that communicates with the CPU, essentially telling the CPU to report a different aperture (f/0.0 perhaps?) if the lock is not engaged. It's just the kind of idiosyncratic, unnecessary thing they would have done in the past.

Tokina made several models of AT-X 28-70 zoom lens Brian. Most were constant aperture f/2.8, but there was also an f/2.6-2.8 version. We'd need to know the exact model to advise on spare parts.

I had one of the early versions, which had a slide switch to lock the aperture ring at minimum, as you've described. Indeed the 'switch' is a flimsy affair, and it came loose on my lens. It was then possible to get the little plastic part in such a position that it prevented the aperture ring reaching minimum aperture - and so gave the FEE error.

The part was easily re-seated in its groove. There was no micro-switch or electrical contact. It's simply a mechanical lock that prevents the aperture ring rotating away from minimum aperture.

I suspect that any other spurious errors must have been due to dirty or corroded contacts, which coincidentally cleared themselves when you removed the lens to repair the 'switch' - (not really a switch, just a locking device).

"with regards to the f22 and slide lock, something has to tell the camera that the lens is in auto mode,..."

The position of the aperture ring is all the camera cares about. As long as the lens pushes the AI coupler to the end of its travel, or the feeler switch on the camera body is activated, then the FEE error goes away. If your camera has an AI ring, you can check this for yourself by pushing the ring to its end stop with a lens mounted and not at minimum aperture. When the ring reaches a certain point the FEE message will go away. There's no electrical switch in the lens.

Incidentally, I found my Tokina AT-X 28-70 to be an average performing lens on film; despite rave reviews of the time, which claimed it used the same optical formula as a far more expensive Angenieux zoom. Whatever. I was never too impressed with it, and found it a pretty unacceptable performer when I went digital.

Agreed - the only way the camera should be reporting a "delta" aperture is if it doesn't know what the maximum aperture of the lens is - and that (on a D700) is communicated electronically; it's one of the more basic aspects of the mount protocol. I'd check all the contacts are clean, and then worry about whether they've all got a solid electrical connection (no corroded electrical joints or cracked wires).

I'm hoping when the lens reports f/2.8 and the lens ring is at f/22, that's because you've set the aperture to f/2.8 on the camera side, and this is overriding the aperture ring. If not, that says something a bit worrying about the aperture follower mechanism on the D700; is it working okay with other lenses?

Again, you could have a play with custom function f9 and change the "aperture setting" option to use the aperture ring, and see whether this works (within its limits). That would stop f/22 being a requirement, but if there are electrical issues there may still be problems.

The lens is the older Tokina AT-X 28-70 f2.8 with the ø72mm filter ring.

So with all this in mind, I can work with the lens in either manual or auto mode. But I would like very much to have the lens in full operational mode as it was designed. So looking for a replacement part for that slide has some importance. If I can fix it I will.

Oops - sorry, I missed that you've presumably had a go with the f9 setting, since you mentioned programming manual lens data. Or do you actually mean you just programmed in a manual lens focal length and f-stop, and the lens is working in full manual (presumably without autofocus)? In which case, the electronics are definitely causing trouble - if the electronics are working, the manual lens data information should be ignored.

If you care about aesthetics, then fixing it is the thing to do. Given that there's no real benefit to using the aperture ring to control the lens (unless you're shooting time lapse), I still think that taping the aperture ring to its f/22 position (ideally with masking tape so you don't mark the lens) would give you "fully operational". But I think we've concluded that the problems were more to do with electronics and contact quality than with the switch. If cleaning everything works, good; otherwise, the fix might be harder and involve some soldering.

Agree Andrew. We certainly can conclude that the fE.E and ⊿Fx error were related to communications between the lens and the camera. I did clean the contacts with alcohol and a lint free cloth. So, again, something worked. LOL

Thanks again.

"So looking for a replacement part for that slide has some importance."

- From the description, it sounds like the same model of Tokina 28-70 that I had. I used it on an F801s (N8008S), which would date it to around the early to mid 1990s. So, sadly, I fear that parts will be unobtainable by now. Except maybe from a used 'parts only' lens.

FWIW, I bought a Tamron SP 28-75 f/2.8 to use on my D700. It was miles better than the old Tokina, and even stood up well to the piercing resolution of a D800. It still does.

However, if you're happy with the Tokina, then I suggest you either glue the plastic slide into place with the lens at minimum aperture, or just live with the aperture ring unlocked. The locking slide was never very secure IME, and used to come unlocked very easily; rendering it almost useless.

It appears that I have a copy of the lens in question, a rather rough constant 2.8 version with a fungus issue, and on this one the lock is a separate piece that's screwed in. I have been using this more as a body cap than anything else, and as has been mentioned above, the lock is pretty loose anyway. If you email me with a mailing address I'll unscrew that little piece and send it to you. Photo,net used to provide emails, and I presume it still does. If not, let me know.

I'm assuming here that the minimum aperture tab on the aperture ring is not broken off. I don't think it is even used on any but the lower end models that do not have an AI follower, but it is necessary for those.

The minimum aperture tab (originally the electronic exposure coupling post for the F2 finders that could rotate the aperture ring) is, indeed, ignored by the D700 - it's only the bodies without an aperture ring that have a switch that's pressed by the EE tab. (Except the D3400, which doesn't.)

Aside: I've only just registered (while checking Hypnoken's compatibility list to ensure I was right about the D3400) that the EE switch arrangement was used on a load of low-end film cameras (notably F55-75) as well as the D100-D90. I'd assumed it was only a few years of dSLR production during which Nikon had failed to notice the issue of camera damage from old lenses before they went to a push-in switch (with the D40, IIRC). It looks like they'd actually had this problem since at least the F50 in 1994. Way to pay attention, Nikon!

Interesting enough, I accidentally pushed to slide off the lens today. I turned off the camera and turned it back on (without touching the lens) and the display was ◿F6. I took the lens off, put the slide back on, put the lens back on it stilled showed◿F6. Had to do the remove lens when power is on to fix it. But now it is back to working.

Might invest in another lens. Either a newer AT-X PRO or the Tamron mentioned by rodeo_joe.

Brian, I got the part back. Sorry it did not work out. If I'd known how brittle that plastic is, I'd have padded it better. It's pretty clear the thing just fell apart in transit.

Ah well. Maybe it's a way of making sure you end up with a better lens.

Yeah, but again, you're a stand up guy to take a part off you lens and send it. In the meantime, I will work on trying to weld my tiny part back together. A toothpick amount of epoxy might do the trick (while viewing under a 20x microscope).

Thanks again Matthew

Update...

I know this has been over a year, but closure is important. I found the part at Pro Camera Repair. It cost $6 and change to $3 and change for shipping. The part is actually for the AT-X Pro lens. I have that lens and I checked to see if it would fit on my older lens. It does. Whoot!

Sorry to revive an old thread, but like I said, closure.

Again, thanks to everyone for your help and advise.