Minolta MD Tele Rokkor 135/2.8 (II): Make one out of two

[Andreas Thaler]

Recently I dedicated myself to the second Minolta MD Tele Rokkor 135/2.8 (II) from my collection of defective lenses.

The rear lens surfaces of this example were also massively dirty.

Unfortunately, in this case I was unable to achieve satisfactory cleaning. The optical assembly retained a cloudy haze, which is unacceptable.

The front optical unit could also only be cleaned to a limited extent; a dirty lens remained out of reach.

Therefore, I decided to turn two copies with defects into one flawless one.

Because I could only get the first telephoto with a slightly different aperture, which is at least a cosmetic flaw.

Tele #1 received the following parts exchanged from tele #2:

• aperture register
• complete aperture mechanism on the bayonet ring
• extendable lens hood (without scratches)

Arranging the dismantled parts.

Cleaning the “new” aperture register with Zippo lighter fluid.

Everything is clean - the lighter fluid evaporates quickly on its own.

This also replaces this slightly dented aperture blade.

Things get lively at the desk

Replacing the spring for the aperture transfer lever.

The spring closes the preselected aperture when the camera is released.

The donated transmission lever, firmly and straight riveted into the cover ring of the aperture register as it should be.

This lever was loose in tele #1.

After soldering in, a minimal misalignment remained, which meant that the aperture opening when the tube was extended (close distance) deviated from the aperture opening at infinity.

Here both levers one behind the other for comparison.

The driver of the aperture ring slides vertically on this lever when focusing.

If the lever is crooked, this affects the aperture opening.

Insert the cleaned aperture blades.

 

[Andreas Thaler]

Adjusting the aperture register

At maximum aperture value (here f = 2.8), the aperture blades must just disappear into the register.

Then the aperture values are formed in steps as you turn the aperture ring up to f = 22.

f = 2.8

f = 8

f = 22

The aperture now remains constant at all distance settings.

The rubber coating on the focus ring is on.

The rear lens surround is installed.

The front optical assembly is already screwed on.

I was also able to improve the dented filter ring by bending it out again.

Make one out of two

I no longer look for the small steel balls under the aperture ring when they fly away when the aperture ring is removed. New replacement is available.

As always, the workspace is crowded after a project is completed.

Spare parts remain for further projects.


I actually wanted to improve tele #2 because it would have saved me having to replace the entire aperture mechanism.

When I wanted to screw in the front optical assembly of tele #1, I discovered that it was not compatible. The thread is, hardly noticeable, laid out differently. There is also an intermediate ring in the unit that the other Tele did not have.

I was amazed, both teles are otherwise from the same litter - at least the same type.

Obviously a modification that was made over the course of production.

+++

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

 

[Individual One]

Thank you for this tutorial. I have the same lens but I hope that I never have to do this level of service to it.
Bruce

 

[Kino]