Tight aperture ring?

[Peter]

Just picked up a K pre Ai 24mm f2.8 Nikon lens $3.00 with a tight aperture ring.
It will close between f4 and f5.6 and then it stops. Looks like clean glass, focus is smoth but also looks like it sat with the rear up open to dust.
Blades are dry and snappy at 5.6. So what could be the issue and how far into the lens do I need to go to inspect or clean?

[richardHaw]

if it's the same lens as this:
https://richardhaw.com/2017/11/04/repair-nikkor-n-24mm-f2-8-auto/

then there is a possibility that the tab on the iris wasn't installed properly and is not sitting within the fork.

another one would be the screw coupling the aperture ring to the fork inside.

that's the only things that I can think of. somebody probably worked on the lens but forgot to put it back properly. don't force it. it could damage the lens

[Peter]

Found it!!
 Took it apart while the screws where out aperture ring moved smooth closed down to f22. Tightened the screws and it was stuck at f22.
Took two of the screws out and loosened the other two it turned but a little tight.
Problem? A dented aperture control ring hanging up on the edge of the lens mount just enough to bind up it's been dropped on the rear edge..
This thing has clean glass but showing dust inside including a tiny dried up husk of a bug bouncing around behind the front element. Also the smooth focusing is not as smooth after gripping it to get the filter off the front, hope i didn't throw it out of wack?
So if i could find a trashed up early Ai 24mm f2.8 with a good ring i am half way in the ball park.
My local 100 miles away repair shop charges $55.00 just to touch a lens, in short he could say yeah it needs to be cleaned and give no quote on the complete job.
I may just take it off and mill it to Ai and mill that spot down as well.
For a $3.00 lens use it on my A6000 or the D700. But that dead bug may cause a random issue, how hard is it to get the front element off?

[richardHaw]

i have a spare aperture ring for that lens but non-Ai 

[Peter]

i have a spare aperture ring for that lens but non-Ai 

Richard,
Just sent a PM to you..
Thanks
Pete

[Peter]

Just watched this video..
I guess little bug will be staying between the elements for awhile..
I don't have big enough guns to go this far into a lens, i have FUBARed a couple trying to dig into them.

https://youtu.be/IYbtN74QIXU?t=11

[Seapy]

Thanks for the link Peter, fascinating, tempts me to delve into my 20mm f2.8.  It took a fall a while back and I had to dig into the front end to extract a broken screw which was jamming the focus.  It focuses now but there is an ugly hole in the front of the lens.  I also suppose the screw which broke might be better if it were replaced...

I can probably make the front cover myself but the front outer piece is crunched, it would be better with a new one.   

[Peter]

See photos good looking glass needs another cleaning..
Pen tip is pointing to the problem also i have never seen flying bugs in a lens in all my years with dealing with cameras and lenses.
I see i have two....

[Seapy]

I see, more of a distortion than my Nikkor AF 20mm f2.8, my son dropped it and my D3, from about 3 feet, the D3 was fine, the lens not so good...  The ensemble landed on the corner of the lens...  The lens works well enough but I do get some funny looks when I'm out and about with it.



The gouge marks were caused by me trying to unscrew the front.    In case anyone is wondering the label says "Store face down".   

I will start another thread when I make a start on it.  The video prompted me to open it up and take a look.  My front piece is what appears to be fibre reinforced plastic.  It's just held on with three screws which are revealed by removing the rubber focus ring.