[Nibby99]

So I know this post might be met with a lot of comments accusing me of blasphemy but here it goes... I do not shoot on Pentax bodies (DSLR or film) and have adapted my 3 Pentax lenses so far to my Canon EOS M (I have a SMC Pentax-M 50mm f1.7 also a 28mm f2.8 and now a Vivitar VS1 70-210 f3.5 Kino (SN 22nnnnnn). In order to fit the lenses on the Viltrox EF->EFM adapter the aperture control pin and shield had to be trimmed back (*GASP*). Suffice to say on the two SMC Pentax-M lenses I was able to do this with the lenses fully assembled and kind of hackishly chopped it off with some flush cutters as the shields were plastic.

On the Vivatar the aperture pin was protected by a metal shield not plastic and seemed so close to the rear lens elements I decided to remove the 5 screws holding the back mount. With the mount off I was able to easily use the dremel to remove the shield and pin. When I reassembled it I took some shots and everything seemed great, that is until I attempted to adjust the aperture and realized it was completely seized. I took it apart again and looked at the mechanism a bit more carefully. Suffice to say after an hour and half last night I realized I have no idea what I'm doing. It nearly seems like it's indexed in some particular way and will require a bit more know how than I have to reassemble this. I did have it working to a point but it seemed like I was missing some aperture stops towards the stopped down side.

I can post pictures, video...etc, if someone believes they might be able to help save this lens. From the 5 minutes I did get to shoot with this it looked amazing. I'd be willing to go on a Zoom call if someone thinks they can walk me through this.

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Last edited by Nibby99; 02-20-2023 at 07:17 AM.

[UncleVanya]

Ugh. Sorry to hear this. Their shield trimming isn't an abomination, those shields only were there as a precaution to protect the aperture levers. Even modern Pentax bodies sometimes require trimming the shields. The levers are more blasphemous. Trimming that makes the lens potentially crippled forever as replacement parts are hard to find except from another lens.

Setting aside the blasphemy… I am sorry to say I don’t know much about the problem or the solution. I’m watching this with interest to see if anyone can help you. Good luck!

[Nibby99]

Ugh. Sorry to hear this. Their shield trimming isn't an abomination, those shields only were there as a precaution to protect the aperture levers. Even modern Pentax bodies sometimes require trimming the shields. The levers are more blasphemous. Trimming that makes the lens potentially crippled forever as replacement parts are hard to find except from another lens.

Setting aside the blasphemy… I am sorry to say I don’t know much about the problem out the solution. I’m watching this with interest to see if anyone can help you. Good luck!

Thanks for the interest in this, I'm hoping someone that is in the know chimes in on this thread.

[UncleVanya]

This may help: Product Details | Vivitar Series-1 70-210mm f3.5 Repair Article | Vivitar | Service Manuals | Learn Camera Repair

[bdery]

In order to fit the lenses on the Viltrox EF->EFM adapter the aperture control pin and shield had to be trimmed back (*GASP*)

I agree with UncleVanya, trimming the shield is normal. Trimming the lever is bad

Did you take notes and pictures while you were disassembling? Are you sure you put things back the way they were?

I'm guessing that by manipulating the lever it got bent or misaligned. In that case a more severe disassembly would be required, by someone who knows what he's doing. A local repair shop maybe? Otherwise, maybe use a small vacuum cleaner to try and remove particulates which might jam the mechanism?

[Nibby99]

This may help: Product Details | Vivitar Series-1 70-210mm f3.5 Repair Article | Vivitar | Service Manuals | Learn Camera Repair

I was actually on that site this morning. None of those looks similar to my revision of the lens :-(

[Nibby99]

I agree with UncleVanya, trimming the shield is normal. Trimming the lever is bad


Did you take notes and pictures while you were disassembling? Are you sure you put things back the way they were?
No, I was tired as stupid. I suspect that might have saved me in this case. I should have scored the barrel / mount to figure out exactly the rotation.


I'm guessing that by manipulating the lever it got bent or misaligned. In that case a more severe disassembly would be required, by someone who knows what he's doing. A local repair shop maybe? Otherwise, maybe use a small vacuum cleaner to try and remove particulates which might jam the mechanism?

I think the lever is ok. I had the whole rear mount off and used the dremel to carefully trim back the guard and was meticulously careful chopping the aperture pin off nearly flush.

[mlt]

I think the lever is ok. I had the whole rear mount off and used the dremel to carefully trim back the guard and was meticulously careful chopping the aperture pin off nearly flush.

Try pushing in on what is left of the pin and see if closes down the aperture. If not, there may be some Dremel cooties inside :-(

[othar]

I think the lever is ok. I had the whole rear mount off and used the dremel to carefully trim back the guard and was meticulously careful chopping the aperture pin off nearly flush.

Without knowing the exact design of that particular lens, my guess would be, that your aperture ring was mounted in the wrong position relative to the aperture blade position and therefore you reached a hard stop of the ring before you reached the stop down position of the aperture blades. Try removing the aperture ring again and see if there is any other position possible to assemble it again

[Nibby99]

Try pushing in on what is left of the pin and see if closes down the aperture. If not, there may be some Dremel cooties inside :-(

shing in on what is left of the pin and see if closes down the aperture. If not, there may be some Dr

e exact design of that particular lens, my guess would be, that your aperture ring was mounted in the wrong position relative to the aperture blade position and therefore you reached a hard stop of the ring before you reached the stop down position of the aperture blades. Try removing the aperture ring again and see if there is any

hat is left of the pin and see if closes down the ape

Both moving the left over aperture nub and the actual mechanism which it engages opens and closes the iris without issues. This is definitely how I'm putting the mount itself back on (since moving the aperture ring engages the rear mount which then has a rod that interfaces with the actual iris/blades. I am going to take a few pics here and post a YT video to see if anyone has any ideas. It really just seems like an indexing issue of some sort. There must be a very particular way of reattaching the rear mount to make it so you get the full range of aperture detents.

[Nibby99]

Without knowing the exact design of that particular lens, my guess would be, that your aperture ring was mounted in the wrong position relative to the aperture blade position and therefore you reached a hard stop of the ring before you reached the stop down position of the aperture blades. Try removing the aperture ring again and see if there is any other position possible to assemble it again

I've attached the lens as it stands right now. You can see in the image the rear mount taken off with the post/pin that engages the notch inside the lens to change the aperture. Ideas on how to properly assemble this?

[othar]

First off I am just guessing here, as I am not familiar with that lens and I don't have much experience with lens assembly myself.

The aperture and the aperture ring can move individually at the moment and you connect them via the part with the pin.
The 5 holes on the last element (with the pin) are evenly spread (as far as I can see), therefore you have 2 or 3 possible ways to assemble the part, depending on how the aperture ring and aperture are positioned relatively to each other when you insert that last part will you get different results:
-aperture ring is set on the widest aperture and the aperture is closed down (or vis-a-vis) -> the aperture ring will not move when assembled and you have a fully closed (or fully open) aperture permanently
-aperture ring is set somewhere in the middle (~f8) and the aperture is fully closed (or open) -> you get limited movement with your aperture ring/aperture and it can't open fully (or it can't close down fully)

-aperture ring is set to the narrowest setting (f22? f32?) and the aperture is fully closed (or vis-a-vis: f3.5 and aperture fully open) -> correct assembly with full functionality

[Nibby99]

First off I am just guessing here, as I am not familiar with that lens and I don't have much experience with lens assembly myself.

The aperture and the aperture ring can move individually at the moment and you connect them via the part with the pin.
The 5 holes on the last element (with the pin) are evenly spread (as far as I can see), therefore you have 2 or 3 possible ways to assemble the part, depending on how the aperture ring and aperture are positioned relatively to each other when you insert that last part will you get different results:
-aperture ring is set on the widest aperture and the aperture is closed down (or vis-a-vis) -> the aperture ring will not move when assembled and you have a fully closed (or fully open) aperture permanently
-aperture ring is set somewhere in the middle (~f8) and the aperture is fully closed (or open) -> you get limited movement with your aperture ring/aperture and it can't open fully (or it can't close down fully)

-aperture ring is set to the narrowest setting (f22? f32?) and the aperture is fully closed (or vis-a-vis: f3.5 and aperture fully open) -> correct assembly with full functionality

-aperture ring is set to the narrowest setting (f22? f32?) and the aperture is fully closed (or vis-a-vis: f3.5 and aperture fully open) -> correct assembly with full functionality

So going on your last suggestion which seemed very likely:


-aperture ring is set to the narrowest setting (f22? f32?) and the aperture is fully closed (or vis-a-vis: f3.5 and aperture fully open) -> correct assembly with full functionality

which when looking at the mechanism seems to be the most logical. I manually set the position internally to to the smallest opening (f22) and then made sure the aperture ring was on F22. This allowed me to reassemble it. Unfortunately it seems like the first few stops below F22 don't do anything to open the aperture, then probably at around F8 it starts to open up then around 5.6 or a half stop in between it stops getting bigger and never seems to open to the same amount as when I manually move the mechanism labelled Aperture Control in my photo to the most open position.

It completely makes sense this 'should' work.

[UncleVanya]

it stops getting bigger and never seems to open to the same amount as when I manually move the mechanism labelled Aperture Control in my photo to the most open position.

It completely makes sense this 'should' work.

This reminds me of the Click and Clack show where they would talk about Stumping the Chump. Clearly something is missing in the method. Sadly no one so far has the answer. Argh. I hope you get the answer.

[Nibby99]

This reminds me of the Click and Clack show where they would talk about Stumping the Chump. Clearly something is missing in the method. Sadly no one so far has the answer. Argh. I hope you get the answer.

Click and Clack show where they would talk about Stumping the Chump. Clearly something is missing in the method. Sadly no one so far has the answer. Argh. I hope you get the answer.

should' work.This reminds me of the Click and Clack show where they would talk

Same here.