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04-02-2016, 06:08 PM   #1
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Help with SMC Takumar 50mm f/1.4 disassembly (I think)

I have a partial Pentax f/1.4 lens. By "partial", I mean I got it without the filter mount ring and without the name ring, but I *think* it is the one that is labelled "SMC Takumar 50mm f1.4" on this page:

Asahi Pentax - Legacy Lens

It's M42 mount but has knurling like that picture on that page.

I've been searching for a mount ring, name ring and the screws, but meanwhile, I wanted to take care of some other things with the lens:

- There's a small dent (it's pushed "in" in a small area of the ring) on one part of the focus ring, but I'm not quite sure what the best way would be to "un-dent" it safely?

- the "ring" that shows the DOF (I think) was kind of band of metal and was spinning around loosely when I rotated the focus ring, so I pulled the focus ring off.

When I did that, I found that DOF ring to be a kind of thin flexible metal band with the distance numbers on it, but I'm not quite sure how it's supposed to be assembled and how it's supposed to work originally?

Is that band supposed to be glued into place or something?

It's possible that the dinged focus ring was "grabbing" hat DOF strip causing it to spin, but I'm not sure at this point.

Here's some pics...

Here are the pieces I have:

The DOF band/ring is the piece that I laid on top of the focus ring. As you can see, it's just a strip of springy metal with the numbers on it.

Here's the dent on the focus ring:

Thanks, and I hope someone is familiar with this lens and can help. I'm still kind of scrounging around for the pieces I'm still missing also (the name ring and the filter ring mount).


EDIT: BTW, this particular lens doesn't appear to be in the disassembly database? There is an "SMC Takumar 50mm f1.4" lens there, but it looks different than this one (the knurling, for one thing).

Last edited by ohaya; 04-02-2016 at 06:23 PM.
04-02-2016, 06:29 PM   #2
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Couldn't you just get a new lens. Last time I looked they don't cost that much...
04-02-2016, 07:26 PM   #3
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Hi All,

I just found this older thread, which I think addresses some of the questions I had:

From that thread, it sounds like the strip (the "distance scale") has to be GLUED back in place, and it seems like there are cuts/marks on the focus ring that mark where the "distance scale" should be positioned!!


I'll give this a try now...

04-02-2016, 08:43 PM   #4
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You might want to contact member dcshooter. They'd more than likely know all about this lens, and maybe have some spare parts.

04-02-2016, 09:17 PM   #5
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QuoteOriginally posted by Auzzie-Phoenix Quote
You might want to contact member dcshooter. They'd more than likely know all about this lens, and maybe have some spare parts.

I may have to do that ...

Ok, I got past the "distance ring" problem - I got that lined up per the thread I posted and glued in.

Now, next thing is I need to clean the back lens group, so I have to get that group out.

I've been looking at this page:

Pentax 50mm f/1.4 strip-down instructions

and I actually had followed that page before for another 50mm lens, but I'm stuck at the part where I'm supposed to remove "three bright slotted screw-heads". On my lens, there aren't 3 slotted screws in the locations. There are 3 philips/star/JIS screws, but when I remove them, the back part of the body is still stuck and won't come apart from the main body.

I think that I do see 3 TINY screws, or I think they might be screws, or maybe they are allen bolts, but they are SUPER TINY... so small that I can barely see them with a (supposedly) 30x magnifying glass.

Are those allen bolts that I need to remove to remove the back part of the body?

Anyone know?


EDIT: It turns out the 3 screws that hold the back are the 3 philips screws in my case. The back part was just really tight.

Anyway, got that out and cleaned the back lens elements and put it back together and then... I found that the aperture is not closing now/any more.

I don 't know if it was closing before all of this, but I thought it was.

It's too late now, time for bed so I'm wrapping up this mis-adventure for now.

EDIT 2: After a few hours of sleep, and clearer eyes, I was able to get the aperture working again.

The problem was that when I was re-assembling the back end with the part that has the diaphragm, I wasn't lining up the "arm" that is inside the back part that has the 2 "prongs" so that the "prongs" surrounded the "pin" on the front part. I had tried a number of times last night, but I was just kind of "guess lining it up" and then putting the 2 parts together.

This morning, I noticed that if I looked through the opening on the back end as I started putting the front end together, I could kind of/sort of see the 2 prongs on the back end arm and the pin on the front end part, enough so that I could line them up as I put the front and back part together.

Ok, this next part may be funny (amusing). I also realized that if I had the aperture set to wide open, then pushing the auto aperture pin in the back didn't make the aperture do anything. This kind of drove me crazy because I thought the aperture was stuck.

So moral of the story is: Slide the aperture screw on the front part so the aperture is closed, before trying to put the 2 parts together. Then, when I push the auto aperture pin, I can actually see that the aperture is working or not!!

Anyway, I'm glad it's back together again, and somewhat clean and fully working!!

Last edited by ohaya; 04-03-2016 at 06:44 AM.

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