Just cleaned my Summitar...

[HuubL]

... and I was surprised to see how much dirt came off of the internal lens surface, the one directly behind the diaphragm. I used methanol and just two swipes with cotton swabs removed all the dirt. This was the only lens surface that needed cleaning, the other internal surface was clean as a whistle.

 

[Sonnar Brian]

I'll bet the pictures come out better after the cleaning!

I've found the same thing on several old lenses, and they feel much better after a cleaning. I always wonder how much the dirt contributes to a lens being tagged as a "dog".

 

[payasam]

Why should just one particular surface collect dirt? Oil vapour from the diaphragm? Difference in glass composition or coating?

 

[HuubL]

Why should just one particular surface collect dirt? Oil vapour from the diaphragm? Difference in glass composition or coating?

I was wondering about that too. If oil residue would build up in the space between the lens elements surrounding the diaphragm you would expect it to condense onto both surfaces equally. This was clearly not the case for my Summitar. Anybody with similar experiences?

The 1936 50 mm F2 collapsable Sonnar that came with my Contax III also has some internal condensate. Could I clean that myself also? Anybody knows how to open the lens?

 

[Sonnar Brian]

The Collapsible Sonnar is pretty easy. There is a small set screw that holds the optics module into the mount. Undo it, and the optics module unscrews. The rear group is easy to get out with a spanner or gromet. Trying to remember- the aperture ring unscrews, revealing a set screw that holds the filter ring on "I Think".

 

[HuubL]

The Collapsible Sonnar is pretty easy. There is a small set screw that holds the optics module into the mount. Undo it, and the optics module unscrews. The rear group is easy to get out with a spanner or gromet. Trying to remember- the aperture ring unscrews, revealing a set screw that holds the filter ring on "I Think".

Thanks Brian,
I'm going to try it... "I think"... ;-)

 

[John Shriver]

Hopefully an uncoated Summitar. Cleaning early coated Leica lenses without damaging (or removing) the coating is very tricky indeed.

 

[HuubL]

It was a coated one (hexagon diaphragm) and I knew about the soft coating. When I finally had it opened (the top part was screwed on VERY stiffly) I hesitated long before I put the cotton in. The lens is super clean now and I don't see internal scratches or damage to the coating. In fact, I was surprised the haze came off so easy. It really wasn't much of a job at all.

 

[tripod]

Is there a set screw or anything similar on a Summitar? The front part ahead of the aperture scale just unscrews, right?

 

[HuubL]

Is there a set screw or anything similar on a Summitar? The front part ahead of the aperture scale just unscrews, right?

Yes, the front part unscrews, but you may have to apply force! I used a canvas camera strap to get some grip and even than I had to use such force that I was afraid I might damage the mechanism. Fact that it didn't damage is proof of Leica quality in my opinion! I. After unscrewing I marked the point were the threads separate in order to make sure that the diaphragm indicator could be set back to the right position. I don't think that that was necessary, but doing so wouldn't hurt. The two lens parts separate at the position of the diaphragm blades! Make sure to open them up completely before cleaning the lens surface behind it. That surface was the only one with dirt.

I wish I had made digi photos of the process, but it's all very straightforward once you get the parts unscrewed. Good luck if you want to try, but take care of the coating!