Tamron 35-70/3.5 17A Adaptall-2: Rescue mission failed

[Andreas Thaler]

The 35-70 came to me with fungus on the lenses and a stiff zoom ring.

Externally well used, some grains of sand, not cleaned for a long time.

I got to work.

The optical elements were removed and cleaned, except for the front lens unit, which I didn't have to fully dismantle because the fungus was on the underside of the second lens and was accessible after partial disassembling.

One of the rear lenses, the fungus on the rise.

Hydrogen peroxide 3 % on lens cleaning paper softened the fungus after a few minutes.

After repeating, reworking with cotton swabs and cleaning with isopropyl alcohol, traces of the fungus remain.

But the result is respectable.

Helicoids separated, cleaned and re-greased.


Unfortunately …

After assembly, I put the lens on my Minolta XG-M to test the lens.

But only blur, only the macro area was sharp.

The long crossroads of troubleshooting began.

Had I inserted the lenses incorrectly?

I checked my documentary photos, changed the positions, front/back - there can always be a mistake.

After disassembling/assembling several times, I ruled out the optics as the cause of the blur.

Since the helicoids were also put together correctly and the image remained blurry even when I turned the first helicoid directly to focus, I suspect the zoom mechanism.

With lubrication I was able to get it running and fully functional again. However, the ring suddenly stopped rotating completely.

I found out the cause.

One or more rollers had disintegrated and were obviously blocking the zoom function.

Here in the tube a double role, and opposite ...

... a single role.

The second roll was either in the tube, or I had already discovered one of its halves (picture above), and ...

... the second half fell on the table.


I didn't have a replacement and several stubborn screws prevented further inspection of the tube.

It's a shame, a lot of work was ultimately unsuccessful, but I also had a lot of practice


Some details

The Tamron zoom's focus ring is secured by a retaining ring with two grooves.

Taking it off gave me some trouble because I couldn't get it into position with any of my adjusting wrenches.

The, mostly, ineffective attempt to drive the ring with a screwdriver ended with a severe scratch because I slipped.

Here WD-40 solved the problem.

After application, the ring could be turned off easily.

Since I planned to clean it anyway, the penetrating oil didn't bother me.

The focus ring is connected and secured to the front helicoid via four small screws.

This also adjusts infinity.

This seems to be a common method with other zooms (e.g. MD 35-70/3.5).

At least something to prepare for.

For wet-damp jobs like brushing helicoids with fuel or cleaning parts with foam, I use kitchen paper on a changing mat as a base.

This absorbs well and can then be easily disposed of.

The aperture locking ball, which is mounted on a spring and is easy to escape, is caught by a plastic bag with a closure.

The aperture ring under which the ball sits can be removed so without stress.


Limits

To move forward here my home workshop would have to be expanded, as far as I can see:

• drilling in metal
• separate metal (shorten screws)
• threading
• process plastics
• knowledge and know-how about it

A challenge - also for the neighbors

For me, the zoom mechanism is basically the citadel of the lens fortress.

So far I've been playing around with the optics, helicoids and aperture registers of simpler lenses.

Everything „just“ needs to be put back together correctly.

But when replacing a bearing, it probably won't work without complete disassembly and the work mentioned.

And it probably won't always be as easy as with the Tokina 25-50, where I only had to drill two holes and screw in two bearings from another lens without taking the zoom mechanism apart. As the threads above show.

My wife recently said very clearly that I should look for a workshop where I can work.

I'm afraid I've reached my limit here in our kitchen

---

Tamron Adaptall-2 35-70mm F/3.5 Model 17A

Tamron Adaptall-2 35-70mm F/3.5 Model 17A

www.adaptall-2.com

+++

All information provided without guarantee and use at your own risk.

 

[xkaes]

At least you are able to get some "parts" out of it for other projects -- like the rubber waffling.

Just one question. Why did you choose hydrogen peroxide to deal with the fungus?

 

[Andreas Thaler]

At least you are able to get some "parts" out of it for other projects -- like the rubber waffling.

That‘s true

Just one question. Why did you choose hydrogen peroxide to deal with the fungus?

Kenneth (mikeno62) recommends it, see in his video here (39:35):

Canon nFD 50 mm/1.8: Cleaning the lenses

For this I follow Kenneth (mikeno62) on YouTube, who explains all the steps in an hour-long video: I really like Kenneth's videos. Not only is his productivity impressive - new videos on lens service are published regularly - but also the calmness with which he goes about his work In two...

www.photrio.com

 

[forest bagger]

Hello Andreas!

Unfortunately …

After assembly, I put the lens on my Minolta XG-M to test the lens.

But only blur, only the macro area was sharp.

The long crossroads of troubleshooting began.

Had I inserted the lenses incorrectly?

I checked my documentary photos, changed the positions, front/back - there can always be a mistake.

After disassembling/assembling several times, I ruled out the optics as the cause of the blur.

Since the helicoids were also put together correctly and the image remained blurry even when I turned the first helicoid directly to focus, I suspect the zoom mechanism.

With lubrication I was able to get it running and fully functional again. However, the ring suddenly stopped rotating completely.

I think you learned now that it is better to check the mechanics before starting to clean the optics.
These half broken rollers are a common problem when you try to refurbish an old lens.

 

[Andreas Thaler]

Hello Andreas!
I think you learned now that it is better to check the mechanics before starting to clean the optics.
These half broken rollers are a common problem when you try to refurbish an old lens.

No, I didn't learn that because I didn't believe the damage was irreparable.

For me, these are learning projects, meaning the experience gained is particularly important.

If I had to make a living as a professional, I would of course proceed differently, as those aren't my lenses.

And then I would look at optimizing time and effort and, among other things, do as you say.

 

[xkaes]

And sometimes, some of those broken/worn-out/deteriorated parts can be replaced with substitute parts or material -- home-made is necessary, such as SUGRU.

 

[forest bagger]

And sometimes, some of those broken/worn-out/deteriorated parts can be replaced with substitute parts or material...

Yes, sometimes that is possible. In the Nikon AF-S DX 18-55/3.5-5.6 G lenses the front tubus moves on three rollers made of simple plastic. If a heavy push against the front tubus happens, at least one of the roller tires breaks.
Some users themselves replaced the broken tire with the wrapping of an electric cable.

 

[forest bagger]

I didn't believe the damage was irreparable.

That is understood, Andreas. Those works are trial and error, of course.
But the grief over some wasted hours for a finally unsuccessful repair may be the same, whether you do it professionally or in private manner.

 

[Andreas Thaler]

That is understood, Andreas. Those works are trial and error, of course.
But the grief over some wasted hours for a finally unsuccessful repair may be the same, whether you do it professionally or in private manner.

I differentiate between

1. repair projects
2. professional repairs
3. practice projects

What you say applies to

• 1 if I'm not relaxed enough.
• 2 if I am charged for the extra time for the repair.
• 3 a clear no, I've already written why