D300 + 20mm f/3.5 MF lens query

[Wileec]

I have a neighbor with some older lenses he used with Nikon film cameras and he lent me a Nikkor-UD Auto 1:3.5 20mm lens that worked well for him. I mounted it on my camera no problem, put the camera in M mode and once I took a couple of test shots got SS and f-stop set and snapped some shots. Now, I'm ready to take the lens off and I'm not finding a way to do so.

I've had this camera since it came out and use a variety of lenses, but never one of this vintage - so what am I missing? I've tried at various f-stops, but don't seem to know the secret handshake. The two-pronged metal tongue on the lens seems to be running into a plastic tab on the camera.

Feeling stuck. Any help out there?

 

[alexf]

Be careful. The lens must be pre-Ai and not converted to Ai or Ais. The prong could damage the camera. I make it a rule never to install pre-AI (not converted) lenses. I have several Ai lenses that work beautifyully.

Somebody else with more experience on pre-AI lenses might chime in and help.

 

[Wileec]

Yeah - I'm feeling a little embarrassed. I figured if it went on so easily, it must be able to come off just as easily - but I don't know how currently.

 

[CraigH]

Try putting the lens at the smallest F-Stop (largest number). Turn it frm the largest to the smallest, then remove the lens. Make sure it stays at the smallest F-Stop as you remove the lens.

If your lens says Nikkor-UD, it's non-AI unless it's been converted. If it doesn't say that, it's probably AI or AIS and safe, but check the serial numbers. If I'm not mistaken the Nikkor-UD 20 f/3.5 was updated to the 20 f/4 somewere around 1973. Around 1977 the 20 f/3.5 came back in AI form until it was updated to f/2.8. What this all means is that your lens is most probably AI and safe on your camera.

 

[Wileec]

Try putting the lens at the smallest F-Stop (largest number). Turn it frm the largest to the smallest, then remove the lens. Make sure it stays at the smallest F-Stop as you remove the lens.

Thanks for the reply - this is the first thing I checked and tried, as it positions the double pronged tongue the furthest distance away from the reference dot for mounting the lens. It rotates all the distance just fine, but no further and not ready to lift off, as I would expect it to.

 

[Wileec]

My current angle of thought, unless directed otherwise, or perhaps confirmed is this. The two-pronged metal tongue has two small screws connecting it to the f-stop ring and I'm thinking if I remove the one that is closest to the plastic pin on the camera body and just loosen the second screw, Ill be able to rotate it out of the way enough to remove the lens. It may be that this little tongue is only connected to the ring, so therefore could be fully removed and it's no big deal to re-attach it once the lens is off. Or, if one was to keep the lens, just leave it off, since there are big indents on the ring to use to rotate it. Just thinking out loud.

 

[Wileec]

Problem solved.

In the absence of other options, I decided to remove the two screws holding the two-pronged metal tongue and it was simple for the lens to come off, then.

Put an AF lens on the camera, just to make sure I was good to go, and everything seems to be back to normal. Will certainly have to be more careful next time.

I learned that this lens entered camera land in November, 1967, and was pretty cutting edge at the time. I'll be interested to check out the test shots I took with it.

 

[ChrisLilley]

Be careful. The lens must be pre-Ai and not converted to Ai or Ais. The prong could damage the camera. I make it a rule never to install pre-AI (not converted) lenses. I have several Ai lenses that work beautifyully.

Somebody else with more experience on pre-AI lenses might chime in and help.

You have it exactly right. Its a pre-AI lens and, if its stuck, it meant that the flange at the back of the aperture ring has jammed on the minimum-aperture sensor switch on the mount. Be very careful removing the lens, because if you break the switch then no CPU lens will work on that body until its repaired.

 

[ultimind]

I broke mine off on my D70 from inadvertently using a pre-AI 55mm f/1.2 for several months. Only broke half of the switch off (WHY IS THIS MADE OF PLASTIC, NIKON?????) so 95% of lenses worked just fine and were able to engage the switch. Some notable exceptions are pretty much any Tamron or Sigma lens can't quite engage the switch. I've been able to jam a little piece of plastic in there to keep the switch engaged at all times, but its by no means the correct solution.

The 55mm f/1.2 was so worth it though :biggrin:

 

[Wileec]

Thanks for the replies.

As I noted in post #7, I was able to remove the two-pronged metal tongue and then the lens came right off - with no damage to the plastic stop on the D300.

I may have access to a pre-AI 50mm f/1.4 so may just remove the two-prong metal tongue right up front, though total manual is a bit of a pain, especially since no EXIF data is recorded. I like to do test shots, pick the best shot, then note the EXIF data for future similar shots. Without the EXIF data, it means a lot of recording and a lot more time tied up in this kind of thing. I can be a little lazy for that. A bit newer lens works better with my camera, so is my leaning.

 

[ultimind]

I may have access to a pre-AI 50mm f/1.4 so may just remove the two-prong metal tongue right up front, though total manual is a bit of a pain, especially since no EXIF data is recorded. I like to do test shots, pick the best shot, then note the EXIF data for future similar shots. Without the EXIF data, it means a lot of recording and a lot more time tied up in this kind of thing. I can be a little lazy for that. A bit newer lens works better with my camera, so is my leaning.

The D300 has a non-CPU Lens Data option in the menus. Just head on over to that menu, input the specific lens information, and now there will be EXIF data accompanying each image. The lens itself shows up as 0.0mm f/0.0, but the focal length and aperture are recorded properly.

 

[Wileec]

The D300 has a non-CPU Lens Data option in the menus. Just head on over to that menu, input the specific lens information, and now there will be EXIF data accompanying each image. The lens itself shows up as 0.0mm f/0.0, but the focal length and aperture are recorded properly.

That's good to know. I'll keep that in mind.

 

[ChrisLilley]

Thanks for the replies.

As I noted in post #7, I was able to remove the two-pronged metal tongue and then the lens came right off - with no damage to the plastic stop on the D300.

I may have access to a pre-AI 50mm f/1.4 so may just remove the two-prong metal tongue right up front,

I'm surprised that you found the prong was what was causing the lens to jam. However, just removing the prong does not make a pre-AI lens safe to mount on your D300. It needs to be AI converted.

though total manual is a bit of a pain, especially since no EXIF data is recorded. I like to do test shots, pick the best shot, then note the EXIF data for future similar shots. Without the EXIF data, it means a lot of recording and a lot more time tied up in this kind of thing. I can be a little lazy for that. A bit newer lens works better with my camera, so is my leaning.

If the lens was AI converted (or was AI, or AIS) then your D300 can be set up to read the aperture ring position directly. Thats what AI (Aperture Indexing) stands for.

 

[Wileec]

Chris - thanks for the education! I'm relatively new to all this lens stuff, so it's great to learn from people with so much experience. Little by little I pick up bits here and there.

 

[CraigH]

Everything you need to know about AI Conversion. John White does a great job and comes highly recommended. I have a Dremel tool, but since he's so inexpensive I don't have to worry about making a mistake.

http://www.aiconversions.com/

 

[Wileec]

Thanks - I'll certainly file that info away.