An MD 35-70/3.5 was sitting on my table looking pretty unsightly and sick.
Actually I just wanted to look through lens repair candidats and leave the screwdriver in the box.
But it was full of dirt, the zoom and aperture rings were difficult or impossible to move, a screw was missing from the rear ring, and I saw clouding on one of the rear lenses.
Without thinking twice, I got to work.
And - contrary to my usual habits - this time I forewent an orderly procedure and documentation
Without a repair manual, video or repair instructions on the web, I let myself run wild.
The exercise was to approach the matter freely and to trust in my ability to complete the repair - and especially the assembly - even without help.
And think as little as possible when working
Three screws loosened - the fourth was missing - and the aperture mechanism was partially exposed.
An actuator gangs here and closes the aperture.
But this actuator wasn't there.
That was quickly resolved.
When installing the rear ring, the actuator only needs to be guided into the recess.
Aperture issue fixed
I moved on to the clouded lens.
The two lens unit was easy to unscrew:
I loosened the screw connection of the unit with the spanner wrench:
The top of the lens, temporarily marked with a water-soluble pen.
This is to ensure the correct side installation.
When I looked closely at the lens, I discovered not only fog, but also fine fungus traces.
I was able to remove both with acetone:
The unit reassembled:
Optical cleaning done
Continue to the blocked zoom ring.
I looked at the lens, turning the zoom ring to understand the mechanism.
The cause of the blocking quickly became apparent.
There was a screw in a guide that certainly didn't belong there:
A game of cat and mouse began.
When I had chased the screw in the guide in circles, my magnetized probe won and the screw was on the table.
I removed some dirt.
And there was a lot of dirt further inside too.
I happily worked on it and got to know other elements of the zoom.
And oops, another screw fell onto the table.
Where do they both come from?
I continued to clean diligently, inside and out:
During reassembly I noticed that the zoom ring rotated freely again.
The helicoids were still well lubricated.
Blocking fixed
While hunting down the screw I discovered a tiny ball that was also in the guide.
I wondered where it might have come from.
The ball is responsible for locking the aperture ring into place.
It lies in a recess and is pressed against grooves on the lens ring with a spring.
I took it there again.
Beforehand, I greased the area a little so that the aperture ring clicks into place nicely:
And now the sporting part of the day began
There was a faint „click“ heard somewhere in the kitchen.
The ball was gone.
A search with a lamp and a bar magnet on the ground was unsuccessful.
After several attempts to organize a replacement from the spares box, I managed to transplant the ball from a before disassembled MD 35-135.
I want to forget that I had to go under the table a few more times over the next few hours
Now I looked at why the rear ring of the lens was only mounted with three screws instead of four.
There stuck a broken screw in one of the holes:
Actually I just wanted to look through lens repair candidats and leave the screwdriver in the box.
But it was full of dirt, the zoom and aperture rings were difficult or impossible to move, a screw was missing from the rear ring, and I saw clouding on one of the rear lenses.
Without thinking twice, I got to work.
And - contrary to my usual habits - this time I forewent an orderly procedure and documentation
Without a repair manual, video or repair instructions on the web, I let myself run wild.
The exercise was to approach the matter freely and to trust in my ability to complete the repair - and especially the assembly - even without help.
And think as little as possible when working
Three screws loosened - the fourth was missing - and the aperture mechanism was partially exposed.
An actuator gangs here and closes the aperture.
But this actuator wasn't there.
That was quickly resolved.
When installing the rear ring, the actuator only needs to be guided into the recess.
Aperture issue fixed
I moved on to the clouded lens.
The two lens unit was easy to unscrew:
I loosened the screw connection of the unit with the spanner wrench:
The top of the lens, temporarily marked with a water-soluble pen.
This is to ensure the correct side installation.
When I looked closely at the lens, I discovered not only fog, but also fine fungus traces.
I was able to remove both with acetone:
The unit reassembled:
Optical cleaning done
Continue to the blocked zoom ring.
I looked at the lens, turning the zoom ring to understand the mechanism.
The cause of the blocking quickly became apparent.
There was a screw in a guide that certainly didn't belong there:
A game of cat and mouse began.
When I had chased the screw in the guide in circles, my magnetized probe won and the screw was on the table.
I removed some dirt.
And there was a lot of dirt further inside too.
I happily worked on it and got to know other elements of the zoom.
And oops, another screw fell onto the table.
Where do they both come from?
I continued to clean diligently, inside and out:
During reassembly I noticed that the zoom ring rotated freely again.
The helicoids were still well lubricated.
Blocking fixed
While hunting down the screw I discovered a tiny ball that was also in the guide.
I wondered where it might have come from.
The ball is responsible for locking the aperture ring into place.
It lies in a recess and is pressed against grooves on the lens ring with a spring.
I took it there again.
Beforehand, I greased the area a little so that the aperture ring clicks into place nicely:
And now the sporting part of the day began
There was a faint „click“ heard somewhere in the kitchen.
The ball was gone.
A search with a lamp and a bar magnet on the ground was unsuccessful.
After several attempts to organize a replacement from the spares box, I managed to transplant the ball from a before disassembled MD 35-135.
I want to forget that I had to go under the table a few more times over the next few hours
Now I looked at why the rear ring of the lens was only mounted with three screws instead of four.
There stuck a broken screw in one of the holes:
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