Minolta MD 35-135/3.5-4.5 (III): Rear lens cleaned. How I got an excellent magnifying glass

[Andreas Thaler]

This new addition was presented to me in almost new condition, but with a cloudy rear lens, when I examined it:

The lens, along with another, is housed in a unit that is screwed into place.

Using a spanner wrench that I inserted into the two grooves on the top ring of the unit, I was able to loosen the screw connection (yellow arrows).

Below is the retaining ring for the lens, which is screwed into the unit, also with two grooves (green arrows):

I unscrewed the unit with a small slotted screwdriver, which I inserted into one of the grooves and against which I turned the lens:

This type of spanner wrench, which is not easy to set to the correct distance, is not suitable for unscrewing as it slips easily and causes scratches.

Here it can be seen on the right of the picture with the rear lens already removed, its retaining ring and the unit that carries another lens.

The plastic pen underneath has been with me since the 90s. A former stylus for a handheld computer, a forerunner of today's smartphones. I used it to move the retaining ring without causing scratches before I applied the screwdriver:

A second spanner wrench was also used.

This is even trickier when it comes to precise settings:

Here I slipped the spanner wrench out of the groove.

The reflective matt black paintwork at this point came off.

I'll fix this with the right color:

The cloudy lens:

I started cleaning.

First the bellows, then the brush, the bellows again and then isopropyl alcohol on a wide cotton swab.

I removed the resulting streaks without leaving any residue with a second cotton swab.

Everything with a critical eye through the magnifying glasses:

The lens is clear …

… and fixed again in the unit with the retaining ring:

The second lens also gets some cleaning with isopropyl alcohol:

The unit is screwed back into the tube and fixed with the spanner wrench:

Where some of the paint is off, I'll make improvements.

It is unlikely that abrasion can be prevented in the grooves by inserting the adjusting wrench.

Nothing tragic

I erased the paint damage caused by the slip with the spanner wrench.

The damage is almost no longer visible, the repaired area is just a little shiny.

Previously:

Afterwards:

Thank you

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Conclusion

• It wasn't that difficult, but it requires absolute concentration, very careful approach and a magnified vision.
• The work is carried out with sharp-edged tools directly over the coated glass. Small damage to the paintwork can be repaired, but scratches on the coating cannot. Particular caution is therefore required.
• Working with the spanner wrench requires a steady hand. It only loosens one screw connection, but is not suitable for unscrewing as it slips easily and is not easy to guide.
• It worked here and everything is crystal clear again.

 

[Andreas Thaler]

Mission II: How I got an excellent magnifying glass

I had a second MD 35-135 on the table.

A fairly worn piece, but I was able to clean the outside easily.

The rear lens also showed clouding. However, ring-shaped, going from outside to inside, clear in the middle.

So I was going to remove the rear unit here too to take a closer look.

This worked, but the ring above the lens with the two grooves stopped me. It was stuck.

I realized that I couldn't do anything about it (today I would try with WD-40) and, in a last attempt completely overtightened one groove with the adjusting wrench.

That was the end of it, the lens remained inaccessible.


So I took the opportunity to disassemble the zoom to get some insights

The tube was also the last stop here.

After loosening a few cross-head screws, it is connected to the inner socket via a large slotted screw.

But the slot is so narrow that none of my screwdrivers could fit into it. Just a small one, but it couldn't do anything.

Since I already had gray traces of lubricant on my fingers, I stopped the dissection:

The front lens will remain in use in its mount, which I removed from the lubricant with acetone.

A strong magnifying glass that I have used on every one of my repair projects since:

Lens seperation

I was still able to remove the rear lens from the second zoom.

I'm not going to show how I did it here, that falls under protection against violence

But it no longer mattered, as the lens with the stuck and already damaged retaining ring could no longer be saved anyway:

What could I find?

• Yes, the more convex side of the lens lies in the tube, ie. I installed the zoom correctly on the other one.
• The ring-shaped haze is located under the surface of the glass. I conclude that the rear lens is faulty cemented, which therefore consists of two elements. I wouldn't have had a chance to clean it, only the Optik-Labor could help. But that's not worth it here, as the costs would be significantly higher than buying a new lens.

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Conclusion

• In keeping with the code that I only treat photographic equipment with defects that can otherwise be discarded or only expensively repaired, if at all, I have done the right thing.
• An honorable rescue attempt that ultimately failed because of a hurdle I couldn't overcome.
• But the lens had already gone to sleep with the cementing problem, probably a long time ago
• There remain experiences and a very useful magnifying glass that the front lens lives on.

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