Olympus Zuiko 65-200/4 Auto-Zoom: Strong lens clouding removed, infinity adjustment

[Andreas Thaler]

For years I lived under the belief that nothing and no one could help my Zuiko Zoom.

One of the rear lenses was so cloudy that only a milky disc could be seen in the LED light.

It couldn't be used for photographic tasks.

Why did I believe that?

Because an Olympus expert told me so.

And of course I didn't know any better.

„Unfortunately, if this particular lens is affected, there is nothing that can be done“, he said.

Fate

I didn't want to accept that.

So I tried to find out myself.

Too beautiful to be abandoned.

I reached the affected lens.

Fog on the glass, front and back.

The lens was restored to clarity by cleaning with isopropyl alcohol.

So what!

The rear optical unit is solidly manufactured and easy to service.

All elements could be removed without any problems.

This ring is covered with rubber.

Another gummed ring can be found further inside.

This means the lenses sit securely in their frames.

Everything back in place.

Only this one lens needed to be cleaned.


Assembly

The chamber …

... into which the rear lens unit is screwed.

The aperture ring locking ball is located on the underside of this ring.

A little spot of grease will keep it in place during assembly.

The locking steps are also greased - sparingly.

One screw has rusted slightly.

Most of it can be removed with a little Ballistol Universal Oil.

And the oil should loosen the remaining rust and protects the metal from further corrosion.

Further assembly

The spring for the aperture lever can be easily attached.

View of part of the aperture mechanism with the stop button at the back and the locking mechanism that secures the lens in the bayonet. The unlock button can be seen at the front.

 

[chriscrawfordphoto]

I have one of these, too. Like yours, it has the fogged element and I was also told it is unfixable. I'm going to try to fix mine now!

 

[Andreas Thaler]

The position of the bayonet ring results from the recess for the locking pin.

Complete again

Contrary to the expert opinion, the zoom has returned to life

So only trust your own expertise

 

[Andreas Thaler]

Unfortunately, it's not a forever solution

What is the cause of the fogging and why did it come back after a few months?

I think it's the rubber ring that is installed in the rear optical unit. It may decompose and give off fumes that condense on the lens.

So I'll leave the ring in place and clean the lens again after some time. The ring is part of the optical system, obviously stables the lens there and as long as it does not decay, it serves a purpose.

 

[Andreas Thaler]

Infinity adjustment

Regardless of having cleaned the rear lens before, it turned out that the focus setting at infinity was incorrect.

To adjust the focus to infinity, the front helicoid must either rotate out or in from the rear one.

To do this, turn the focus ring with the infinity marking and distance scale, which align with a marking line on the tube.

If the infinity mark and the marking line match, the lens is set to infinity.

For adjustment, the focus ring can be decoupled using screws. It then no longer moves the front helicoid.

Using the viewfinder and focusing screen, you turn the front helicoid (grab the front tube) to focus on an object that is far enough away and represents infinity.

The focus ring is then reattached (coupled) with the screws.

Infinity is thus adjusted.


Looking for the screws

Since I haven't dismantled a sliding zoom yet, I'm looking for the suspected adjustment screws.

The front lens is attached with a decorative ring.

I can take it out of the tube, see the lens underneath, but no other adjustment options.

This is what the massive lend looks like:

I reinstall the lens again.

Another retaining ring fixes the extendable lens hood.

I also loosen this with the adjustment wrench after adding a little WD-40, as the ring is reluctant.

I can now remove the lens hood.

But there are no screws to be seen here either.


Only the tube remains ...

... under the rubber coating of the focus ring.

Things have to continue there.

So I take off the rubber coating.

It is only weakly glued, but it fits very tightly:

And here they are, the adjustment screws that connect the focus ring to the front helicoid.

Five pieces in total:

After loosening the screws a bit, the focus ring can be moved up a little:

I spend some time studying the mechanism.

From the window I focus on the construction crane boom in the background using the front helicoid.

The neighbors all around are probably already used to my strange actvities. Nobody calls the police

I now know by experience that the boom focuses a little below infinity.

It's not entirely accurate, but I compared it with other lenses and it can be readjusted at any time.

Once I'm happy with the setting, I screw in two screws and also the remaining three.

Now infinity has been adjusted.


The more pleasant work follows

Cleaning the lens hood, its retaining ring and the thread on the tube from WD-40. An antidote is isopropyl alcohol

The lens hood is put back on.

The retaining ring can be easily screwed in and fixed:

Done:

 

[Andreas Thaler]

Special thanks to the ingeniously designed and super stable Minolta TR-1 table tripod for supporting this project!

+++

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

 

[Andreas Thaler]

I have one of these, too. Like yours, it has the fogged element and I was also told it is unfixable. I'm going to try to fix mine now!

Good luck!

 

[Olympus Zuiko]

Hello Andreas, I read your article about cleaning the Milky glass element of the Olympus Zuiko 65-200mm. Thanks to your article I managed to remove the tube where you can find the Milky glass element too. But I cannot reach itvat both sides. IThe flat lens element with the rubber ring is preventing this. How did you remove this element? I tried to remove the rubber ring with s wooden tooth pick. But this resulted in damaging the rubber ring.. I hope you can help me.

 

[Andreas Thaler]

Hello,

that was a while ago, so here are the photos from the thread again.

Such lens units are almost always screwed on. They can be removed either by hand, with a rubber sheet to increase friction, or with one or two pliers, although this is the most dangerous method as it can leave marks. A thick rubber sleeve between the jaws of the pliers would be an option. WD-40 can help to loosen the threads, nothing is glued here.

The lenses are then simply inserted and can be lifted out with the lens sucker, making sure that they are inserted the right way round. The rubber ring should be the cause of the fog, it is probably plastic that is decomposing.

 

[Andreas Thaler]

I remember the ring at the top holds the unit in place. If you unscrew it, all the parts should come out. Maybe the ring is stuck.

 

[Andreas Thaler]

It could also be a cemented lens that is foggy on the inside. There is nothing useful that can be done about it. Or the fog is on the outside.

 

[Olympus Zuiko]

I remember the ring at the top holds the unit in place. If you unscrew it, all the parts should come out. Maybe the ring is stuck.

Thank you so much for your help. I fear that one part of the tube is stuck which means I cannot reach the problematic lens. I tried some fluids like Aceton, alcohol and ED40 but nothing looks like having effect. You think you were able to unscrew the ring around the upper flat lens or which part did you unscrew exactly. I hope you can still remember. I post a photo with the problematic tube with inside the foggy lens.

 

[Andreas Thaler]

You think you were able to unscrew the ring around the upper flat lens or which part did you unscrew exactly.

Yes, exactly, the ring on top.