Not a repair, but determination of the fault and dissection
I was unable to repair this Tamron.
I failed due to a collection of tiny balls in the aperture bearing and the complexity of the lens.
But I was able to work my way to the lens opacities, which are haze that can be removed.
There are two contaminated lenses. One is above the aperture, the other in the middle of the barrel.
To get to them, I had to completely disassemble the zoom. In the process, I scattered the aperture bearing balls in the barrel. I was only able to remove them all once I had completely disassembled the lens.
In addition to gaining insight into the interior of this complex lens, I was also able to get a large number of plain bearings, balls and screws for my spare parts inventory.
The rear lens unit can be removed after loosening three screws.
In order to get to the lens unit underneath, where I suspected the clouding, I unscrewed this retaining ring.
There are tiny balls here that act as bearings for the aperture. The balls are magnetic.
I reinstalled the retaining ring and attempted to continue the disassembly by removing this cover ring.
Then I loosened the retaining ring again to remove the balls, in the hope of getting closer to the lens unit. The balls rolled into the tube and most of them stayed there, held in place by magnetism and grease.
This meant that the repair attempt became a dissection. I wanted to at least find out whether the opacities could be removed and where they were located.
The components of the zoom. Metal and plastic, quality workmanship.
The opacities were on two lenses. One of them was above the aperture (left unit containing the lens) ...
… and the other on the inside of a lens in the middle of the tube.
Both lenses could be cleaned with isopropyl alcohol.
Replenishment for my spare parts warehouse. Plain bearings, balls, screws, springs and two tiny circlips.
Conclusion
- In order to clean the two affected lenses of this zoom, it must be disassembled in depth. Be careful with the balls, they are volatile.
- Successful disassembly is based on experience, but this is only of limited help, as each lens has its own special design.
- Even a repair manual with the usual exploded drawings does not show the correct order of the individual steps when disassembling.
- Therefore, successful disassembly/assembly requires two prerequisites: meticulous documentation of all steps taken when disassembling and motivation.
- Since I now have a replacement for the lens and it is not a particularly valuable item, I decided not to go to this trouble
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