Worth polishing flat element in Serenar 35 3.5 ?

[MarkWalberg]

I have a Canon Serenar 35 mm f3.5 that I’ve had a long time. I love the tiny size, similar to the Canon 25 mm lens. It performs OK but contrast is pretty low.

It has a lot of haze on just one surface, the element just behind the iris. The rest of the surfaces look great. Most of the haze stays despite every cleaning I can think of, except that I didn’t try lighter fluid or ammonia yet. Water, ethanol, peroxide, baking soda in water didn’t help. (Not all together, of course.)

The surface with the haze looks completely flat. This lens is said to have the same construction as the Elmar 35 f3.5. The internet tells me that the Elmar has a flat surface there, too.

So, it seems like it would be pretty easy to polish that flat surface to get rid of the haze.

What do you think? Is it worthwhile for me to do this? I’m guessing that a light polish to this flat surface will get rid of the haze to improve contrast without hurting the image otherwise.

 

[mdarnton]

What do you have to lose?

 

[peterm1]

It's worth trying. Be aware that early post war coatings tended to be soft though I believe Canons were less so than Leica's. Nevertheless, there is a chance that the coating can be removed by polishing. Also, if the haze has been in place for a long time, it can be difficult or impossible to remove without extensive polishing which again increases the chance of removing any coatings that might be present. I have had to clean a number of lenses including a (later) Canon 100mm f3.5 but in that case I found the haze to be persistent and unable to be removed without damage to coatings so I left it. Nevertheless, I did reduce the haze and now unless its shot against the light it's not too bad. What I mean is some reduction may be better than none or too much.

 

[Sonnar Brian]

Do not worry about the coting- the glass is etched, I've seen it one several. Worth a try Cerium Oxide is usually used for glass. I've read people using Tooth paste to silver polish.

 

[rfaspen]

Especially if flat, you have nothing to lose. Wouldn't worry about any coating...not helping you now and without removing the haze it can't anyways.
Toothpaste worked for me on a non- camera lens. I would consider it for a camera lens such as yours.

 

[Phil_F_NM]

Cerium oxide paste is cheap and a small bottle will last you a very long time. Sounds like the flat surface is etched as has been mentioned, possibly by fungus from long ago. To keep the element surface perfectly flat, use a piece of glass as your polish tool with the paste between it and the lens element.
Phil