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Missing Aperture Blades For Takumar 83mm Lens
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PostPosted: Wed Jun 13, 2018 8:48 pm    Post subject: Missing Aperture Blades For Takumar 83mm Lens Reply with quote

I recently found/bought an early Takumar 83mm F1.9 lens. I had no idea that this lens ever existed. I was not actively searching for this lens, it was by a complete chance. I've since learned that this lens is quite a collectors item and quite expensive. I've read someplace that about 1,000 of these were ever made.

The glass and body are in good condition, but its missing 2 aperture blades, I was fully aware of this when I bought the lens. I can fully open the lens to F1.9 and close it down to about F4, almost F5.6, but any higher and 3 aperture holes start to appear. Ive tried to look for replacement blades/parts/donor lens, but it pretty much impossible to find anything for this lens. I've tried buying (2) old Takumar lenses (135mm F3.5 and also a 55mm F2), but the aperture blades are not compatible due to size.

Does anyone know if any late 1950's/early 1960's lenses made by other Japanese lens makers might be compatible? The lens has 10 blades (minus the missing two). The blades are somewhat "L" shaped and have two small "pins" or "rivets" to hold them in place. Does anyone know if you can have aperture blades custom made? How hard would it be to replace the entire aperture diaphragm?

I'm happy to shoot at F1.9, but I'm hoping to restore it to its full potential. Any advice would be appreciated.

#1


#2


#3 - Aperture at about F4.


#4 - Aperture at F22


PostPosted: Thu Jun 14, 2018 12:43 am    Post subject: Reply with quote

Lens Repairperson.


PostPosted: Thu Jun 14, 2018 1:36 am    Post subject: Reply with quote

Good luck. Hopefully you can restore it to its full glory. Interesting lens. I also was unaware of this lens and I payed a lot of attention to the ebay takumar lists for a couple of years!


PostPosted: Thu Jun 14, 2018 3:00 am    Post subject: Reply with quote

You could ask SK Grimes.
They used to do things like this for large format lenses, IIRC.


PostPosted: Thu Jun 14, 2018 7:06 am    Post subject: Reply with quote

Awesome you found this lens. Good luck with it!


PostPosted: Thu Jun 14, 2018 9:54 pm    Post subject: Reply with quote

Very nice lens.

If that were my lens I would disassemble the lens and attempt to repair the aperture. I have successfully repaired apertures which appeared to be in much worse condition than what you have.

Have to question blades being missing. That strikes me as HIGHLY unlikely. For blades to be missing another owner would have to have disassembled the lens and aperture, removed one or more blades, and then reassembled the aperture and lens without those blades.

It seems more likely to me that one or more of your blades has become dislodged from the cage. The aperture must be completely disassembled, each blade individually and carefully cleaned and flattened (to the extent possible) if necessary and the cage carefully cleaned, and then everything carefully reassembled. Try to avoid operating (opening and closing) the aperture in its present condition, as damage can occur under existing circumstances.


Last edited by guardian on Thu Jun 14, 2018 10:15 pm; edited 1 time in total


PostPosted: Thu Jun 14, 2018 10:15 pm    Post subject: Reply with quote

guardian wrote:
Very nice lens.

If that were my lens I would disassemble the lens and attempt to repair the aperture. I have successfully repaired apertures which appeared to be in much worse condition than what you have.

Have to question blades being missing. That strikes me as HIGHLY unlikely. For blades to be missing another owner would have to have disassembled the lens and aperture, removed one or more blades, and then reassembled the aperture and lens without those blades.

It seems more likely to me that one or more of your blades has become dislodged. The aperture must be completely disassembled, each blade individually and carefully cleaned and flattened (to the extent possible) if necessary and the cage carefully cleaned, and then everything carefully reassembled. Try to avoid operating (opening and closing) the aperture in its present condition, as damage can occur under existing circumstances.



Thanks for your reply. The gentleman I bought it from said he tried to have it repaired, but was unable. I can verify that the other 2 blades are missing and not dislodged.


PostPosted: Thu Jun 14, 2018 10:22 pm    Post subject: Reply with quote

DonN wrote:



Thanks for your reply. The gentleman I bought it from said he tried to have it repaired, but was unable. I can verify that the other 2 blades are missing and not dislodged.


Not quite certain what you are saying. Are you saying an unsuccessful repair attempt was made, and the repairer actually reassembled everything while leaving aside two of the blades!! I have never heard of such a thing.

Of course if the previous owner only tried to have the lens repaired, but was unable to locate a person to execute the repair, then the blades should still be there. Aperture blades do not generally dislodge themselves and then fall out of a lens. They need help!

ETA

I do not know this lens. It is rare and unusual. I do not know how many blades it is supposed to have. Does anyone know?


PostPosted: Thu Jun 14, 2018 10:36 pm    Post subject: Reply with quote

guardian wrote:
DonN wrote:



Thanks for your reply. The gentleman I bought it from said he tried to have it repaired, but was unable. I can verify that the other 2 blades are missing and not dislodged.


Not quite certain what you are saying. Are you saying an unsuccessful repair attempt was made, and the repairer actually reassembled everything while leaving aside two of the blades!! I have never heard of such a thing.

Of course if the previous owner only tried to have the lens repaired, but was unable to locate a person to execute the repair, then the blades should still be there. Aperture blades do not generally dislodge themselves and then fall out of a lens. They need help!

ETA
I do not know this lens. It is rare and unusual. I do not know how many blades it is supposed to have. Does anyone know?


It should have 10 blades. I believe he said that 2 blades were damaged. I do not know the blades were damaged or where they are.

You can read more about this lens here: https://www.pentaxforums.com/lensreviews/Takumar-83mm-F1.9.html


PostPosted: Fri Jun 15, 2018 1:09 pm    Post subject: Reply with quote

DonN wrote:


It should have 10 blades. I believe he said that 2 blades were damaged. I do not know the blades were damaged or where they are.



I can completely understand damage to the blades, which sadly is not uncommon especially if an impaired aperture is forced to operate. I surely understand more than one blade might be damaged. I have seen this with my own lenses.

What I cannot understand is blades actually being missing . . . i.e., gone . . . unless the lens was disassembled, then the aperture was disassembled and blades removed, and then finally the aperture was reassembled and replaced back into the lens with blades actually missing. Who would do such a thing as that!

And, again, if two blades are only damaged there is at least a chance for a repair. Obviously if blades are missing no repair is even possible.


PostPosted: Fri Jun 15, 2018 1:32 pm    Post subject: Reply with quote

guardian wrote:
DonN wrote:


It should have 10 blades. I believe he said that 2 blades were damaged. I do not know the blades were damaged or where they are.



I can completely understand damage to the blades, which sadly is not uncommon especially if an impaired aperture is forced to operate. I surely understand more than one blade might be damaged. I have seen this with my own lenses.

What I cannot understand is blades actually being missing . . . i.e., gone . . . unless the lens was disassembled, then the aperture was disassembled and blades removed, and then finally the aperture was reassembled and replaced back into the lens with blades actually missing. Who would do such a thing as that!

And, again, if two blades are only damaged there is at least a chance for a repair. Obviously if blades are missing no repair is even possible.


I've seen aperture damaged beyond straightening/reflatting of one or more blades. In this case I can easily imagine two such beyond repair blades; Repairperson with no other choice but to reassemble without those to retain an adjustable aperture, albeit missing two blades.

Actual repair is possible by making a couple replacement blades from shim stock.