NikonGear'23

Gear Talk => Lens Talk => Topic started by: Zang on May 05, 2019, 22:18:07

Title: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 05, 2019, 22:18:07
Hello all,

I am disassembling Nikon 24mm f2.8 AI and want to get to the aperture. I was able to separate the objective assembly and can easily separate the rear element from the inner helicoid (please check the picture below). Now I get stuck on how to get to the aperture. Does any one know? Would greatly appreciate your inputs!

Cheers,
Zang
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Roland Vink on May 06, 2019, 01:31:33
Richard Haw does not (yet) have anything specific to the AI 24/2.8 but his lens repair articles should help:
https://richardhaw.com/lens-repair-articles/

Note that the AI 24/2.4 has floating elements (close range correction) which mean there are two sets of focus helicoids, one for the front group and one for the rear elements, so this lens lens is more complicated to repair than simpler lenses.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 06, 2019, 17:53:58
Thanks Roland. Rick's block was the first thing I started with. Also, I have passed the double helicoid stage and now dealing with the objective block alone. It seems getting to the aperture may require taking the objective apart. Will update here if I found it out.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Jack Dahlgren on May 06, 2019, 19:45:13
Hello all,

I am disassembling Nikon 24mm f2.8 AI and want to get to the aperture. I was able to separate the objective assembly and can easily separate the rear element from the inner helicoid (please check the picture below). Now I get stuck on how to get to the aperture. Does any one know? Would greatly appreciate your inputs!

Cheers,
Zang


Looks like if you remove that set screw you should be able to unscrew the front element. Mark before disassembling!
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 06, 2019, 21:22:20

Looks like if you remove that set screw you should be able to unscrew the front element. Mark before disassembling!

No, that's the focusing guide, removing it will be disaster :-P
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Jack Dahlgren on May 07, 2019, 02:26:52
No, that's the focusing guide, removing it will be disaster :-P

I'm thinking the screw marked in red.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 07, 2019, 04:17:57
I'm thinking the screw marked in red.

Oh no, there is no screw there.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Erik Lund on May 07, 2019, 12:17:59
Basically same as this one:


https://richardhaw.com/2017/11/04/repair-nikkor-n-24mm-f2-8-auto/ (https://richardhaw.com/2017/11/04/repair-nikkor-n-24mm-f2-8-auto/)


Richard has documented these very well!


BTW aperture blades ;) not leaves,,, could be why you didn't find it :)

Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 07, 2019, 13:18:39
Basically same as this one:


https://richardhaw.com/2017/11/04/repair-nikkor-n-24mm-f2-8-auto/ (https://richardhaw.com/2017/11/04/repair-nikkor-n-24mm-f2-8-auto/)


Richard has documented these very well!


BTW aperture blades ;) not leaves,,, could be why you didn't find it :)

Thanks Erik, I also have read this. There is nothing about servicing aperture blades. Also, I googled all possible English name combination :)
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Jack Dahlgren on May 07, 2019, 18:19:54
Thanks Erik, I also have read this. There is nothing about servicing aperture blades. Also, I googled all possible English name combination :)
Did you get it apart?
Should look like this:
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 07, 2019, 19:01:09
Did you get it apart?
Should look like this:

Hey Jack, I have passed this too. Still do not see the aperture. I just stop here to take time for more research. I am not sure if I can take apart the block shell without disassembling each element. They are really hard to disassemble and I do not want to risk, unless necessary.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Jack Dahlgren on May 08, 2019, 04:34:52
Hey Jack, I have passed this too. Still do not see the aperture. I just stop here to take time for more research. I am not sure if I can take apart the block shell without disassembling each element. They are really hard to disassemble and I do not want to risk, unless necessary.

Not sure what you mean about not seeing the aperture. It should be between front objective and rear. Maybe it is wide open? Take a photo looking down the center from both ends.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: richardHaw on May 08, 2019, 04:57:06
pictures of my hands are all over the internet. people can hire fortune tellers and predict my future  :o :o :o

i wouldnt advise working on this lens if you are a novice. the iris can be adjusted and that is dangerous if you dont know how to put it back again ::)
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 08, 2019, 05:13:58
Not sure what you mean about not seeing the aperture. It should be between front objective and rear. Maybe it is wide open? Take a photo looking down the center from both ends.

Hey Jack, by not seeing the aperture I mean it is still behind the glasses. I think I figured out the way to get into it. Will update later.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 08, 2019, 05:16:40
pictures of my hands are all over the internet. people can hire fortune tellers and predict my future  :o :o :o

i wouldnt advise working on this lens if you are a novice. the iris can be adjusted and that is dangerous if you dont know how to put it back again ::)

Hey Rick... wise advice as I am a novice+inappropriate tools, but it is too late :) In the worst case I am one lens less :)
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Erik Lund on May 08, 2019, 14:51:43
The red circle in reply #5 indicates a hole, when they close/lock the lens together, they drop sticky glue there, put a bit of disolvent and vait a little and unscrew it. Mark it first


The 1 cm long slot with cross screw is the aperture blade adjustment, mark where it is.
The arm moving is the stop down arm for the aperture blades,,,


https://www.youtube.com/watch?v=IYbtN74QIXU&t=2035s (https://www.youtube.com/watch?v=IYbtN74QIXU&t=2035s)
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Erik Lund on May 08, 2019, 14:54:31
And here how to do the rest as well:


https://whatdoineed2do.blogspot.com/2018/04/nikkor-24mm-f28-ai-s-disassembly.html (https://whatdoineed2do.blogspot.com/2018/04/nikkor-24mm-f28-ai-s-disassembly.html)


For the Ais, same same,,, more or less ;)
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 08, 2019, 17:45:58
And here how to do the rest as well:


https://whatdoineed2do.blogspot.com/2018/04/nikkor-24mm-f28-ai-s-disassembly.html (https://whatdoineed2do.blogspot.com/2018/04/nikkor-24mm-f28-ai-s-disassembly.html)


For the Ais, same same,,, more or less ;)

Thanks Erik,

Just a quick idea, after removing all the optical element leaving the casing and aperture mechanism alone I may consider washing and drying the whole casing and the aperture blades/mechanism without further disassembly work. Do you guys think that would work?
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Nasos Kosmas on May 08, 2019, 20:23:10
I did the same on a 50 1.4 als with sticky blades
You have to remove the glass as a whole part and then you remove all the iris mechanism , you disassembly, clean an assembly again
It was easy for this lens, for your lens I don’t know the approach must be similar  :D
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 08, 2019, 20:27:14
Do you think this would work? Without disassembling aperture mechanism, I would dip the whole casing with aperture in the cleaning solution for a while, close-open the aperture a number of times to wash the oil and then dry the whole thing.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Nasos Kosmas on May 08, 2019, 20:41:03
I don’t find it a good idea, leave the grease of the helicoids untached
If you find the the way to remove the optical blocks it’s easy(I don’t remember the front or the back for iris), I didn’t removed all, only the part you have to reach iris mechanism
Take your time and study the related videos and Richards website
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 08, 2019, 20:48:22
I don’t find it a good idea, leave the grease of the helicoids untached
If you find the the way to remove the optical blocks it’s easy(I don’t remember the front or the back for iris), I didn’t removed all, only the part you have to reach iris mechanism
Take your time and study the related videos and Richards website

What I meant was, I would remove all optical elements leaving only the metal casing with the aperture mechanism. I would not wash it with any of the glass lenses. And there is no helicoid here in the objective block.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Nasos Kosmas on May 08, 2019, 21:58:48
You can try
Dissolvents don’t clean sometimes 100% they may leave spots, use a very soft brush
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Erik Lund on May 09, 2019, 11:37:28
It will absolutely not work!
You will ruin the lens.


Aperture blades must be completely clean or they will not be snappy.


Not possible at all sorry.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 09, 2019, 14:34:38
It will absolutely not work!
You will ruin the lens.


Aperture blades must be completely clean or they will not be snappy.


Not possible at all sorry.

Makes sense. And I have gone too far to be lazy.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 12, 2019, 17:13:29
I was able to disassemble the aperture, clean it thoroughly and put it back happily. Thank you everyone for your inputs. I will put together the lens and give feedback here soon.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Per Inge Oestmoen on May 15, 2019, 02:19:54
I was able to disassemble the aperture, clean it thoroughly and put it back happily. Thank you everyone for your inputs. I will put together the lens and give feedback here soon.


Very interesting! How did it go?

Per Inge Oestmoen, Norway
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 15, 2019, 16:45:15


Very interesting! How did it go?

Per Inge Oestmoen, Norway

Hi,

What I did was I remove the front group then the middle group as the whole. I ended up buying another divider(compass) to make a second round-ended spanner for the middle group. Then I remove the aperture setting screw, then the ring then another ring then all the blades. I did not take a lot of pictures, jut trusted my memory :)
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Nasos Kosmas on May 15, 2019, 19:31:35
Nice, now put the lens back to see it working, it’s a good memory check!
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 15, 2019, 20:18:01
Nice, now put the lens back to see it working, it’s a good memory check!

i did put together the objective and re-grease the CRC helicoid. I am not done with the outer case, though. The bayonet mounting screws turned to be the most challenging thing as they were extremely stubborn. I needed to give it to the repair shop and they drilled one of the screw through. I got the case back and will re-grease the outer helicoid tonight. Will have some test pictures tomorrow.
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 19, 2019, 00:29:03
I ran into a frustrating issue as I stripped one of the screws. Spent another evening at a friend's home who had a dremel tool and micro drill bits. I have put together everything and taken a few test pictures. Still the same (or more or less :) ) stunning picture quality so I guess I did not break anything :)

Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Nasos Kosmas on May 19, 2019, 07:33:11
Very nice,  every thing is back correctly
How did you managed with the screw, you replaced with new one?
Title: Re: Cleaning Nikon 24mm f2.8 AI aperture leaves
Post by: Zang on May 19, 2019, 16:09:22
Very nice,  every thing is back correctly
How did you managed with the screw, you replaced with new one?

The screw was one of the 3 screws that fix the silver "handle-ring" to the case (not sure how to name it correctly). Despite very careful working with screws, one of them got stripped momentarily. Luckily, the screws are hidden under the aperture ring so I drilled off the bad screw head and drilled a new hole and put a new screw next to it. I took a screw from a donor broken watch and used the dremel to shape the head to the desired shape.