The Sankyo Kohki Komura 1:2.5 f=105mm, whose pictures were recently posted on this same thread, has finally arrived from Japan.
The W-Komura 1:3.5 28mm is on its way.
As soon as I picked up the lens from the post office, I couldn't help myself... the first thing I did was to open the lens and try to clean it.
The 2.5/105mm is not one of the super-fast short tele for which Komura is famous, but it's quite desirable and not exceedingly expensive.
I paid mine a very decent price, because it looked pitiful in the pictures, and all the defects were disclosed (well... more or less).
In reality the lens was even worse than expected. There are two tiny scratches on the front glass, and the lens was so hazy, dirty and fungus infested that I could barely see through it!
The good news is that the scratches are not going to affect the optical performance, and that I could clean the objective... I'd say with a success ratio of about 70%.
The surfaces in front and behind the diaphragm could not be cleaned cause I didn't find a way to do it without completely dismantling the objective.
Even after freeing (and sliding back) both the diaphragm ring and the preset ring, I could not remove the third lens (group?) from the front.
I didn't want to try too hard cause it's valuable lens, at least to me, so I will use it the way it is (much, much better!) until it goes in the expert hands of my friend/repairman.
I got su frustrated by my lack of understanding of how the Komura is built, that today I decided to give me another chance.
I had a Soligor C/D 5.6/400mm with a broken diaphargm mechanism, that was hastily repaired with the tip of a wooden skewer
I reopened it, trying to replace the little wooden pin with something more resistant, that would not come loose inside the lens. I got into a number of problems, seriously tested my patience, but in the end I solved the problem with some thin iron wire. Now the lens works a charm in auto, with the diaphragm lever doing what it is supposed to do!
It was not dark, so I went for another lens, an SMC Pentax 3.5/24mm with haze and some fungi, that was bought with the hope to clean it.
I cleaned all surfaces of each and every group. The usual cleaners were not enough, so I used a touch of hydrogen peroxide... and now I have a lens that is 99% clean.
It seems I can't find a way to get rid of each and every particle of dust... but it's cleaner than most of my vintage lenses, so I called it a day.
Three lenses done in two half afternoons. I feel satisfied
Here is the Komura after the treatment. Compared with the pics I already posted, it looks another lens!