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 lens 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.

 

[Andreas Thaler]

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.







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

 

[Andreas Thaler]

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.

 

[Andreas Thaler]

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.

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Conclusion

• Manufacturers often provided service manuals for lenses, but not disassembly guides.
• You therefore have to figure out how to take the lens apart on your own.
• I have since expanded my equipment collection and now carry out such repair projects using the Camera Tester (to check the apertures) and the autocollimator (to adjust for infinity).

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See also

Minolta MD Tele Rokkor 135/2.8 (II): Restored from total loss

Checking the focusing system of an Olympus OM-4. Definition of a workflow for checking and adjusting sharpness

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A word of caution

Please keep in mind that you’ll be using highly flammable solvents for service work, and their fumes are harmful to your health. Soldering also produces fumes that should not be inhaled. Dangerous high voltages can be present when handling electronics, especially in conjunction with electronic flash units and mains. Therefore, familiarize yourself with the safety regulations beforehand and ensure your safety. Depending on the activity, protective gear may be advisable.

All information is provided without guarantee. Any action you take upon the information in this report is strictly at your own risk.

This report describes my personal experience and approach; it does not constitute a professional or certified repair instruction. I am not liable for any property damage or personal injury resulting from actions taken based on the information provided in this report.

Acknowledgments

Without the work of Master Larry Lyells, in particular, we wouldn’t have the detailed technical information we need today for service/repair of electromechanical SLRs.

The SPT Journal and The Camera Craftsman, which he helped shape significantly as an author, and which contain all the necessary information and instructions are available for a fee through Learn Camera Repair.

We owe our access to them to Eugene Pate, the founder of Learn Camera Repair.

As a Shodan in Jiu-Jitsu, I view camera repair as part of my Do, the Way. I am grateful to my revered Grandmaster, Erich Ebetshuber, 10th Dan in Jiu-Jitsu, for everything I have been privileged to learn from him.