'Natural' lens coatings.

I put this up on a just-previous thread but thought it, maybe, worth

one of it's own:

 

A chap who gave us art students a crash coarse in photography (1960s

Bristol) believed that old, old lenses aquired a natural coating. I

can well believe this ; if you have ever dug up a very old bottle, in

the garden, the glass surface has often begun to stratify giving it a

rainbow, or even a gold colour,- a perfect looking coating.

 

Any thoughts ? Is this why very old Elmars give such interesting

results ?

 

Adrian.

I think it is true and is probably how they discovered the benefits of coatings in the first place.

Yes correct, then years where spent trying to do it.

The glass oxidizes to form a film on the surface.

Hi Adrian - I replied on the earflier 50mm thread: fascinating - and very probable. My old 1930 Leica I standard Elmar, however, shows no sign of it, - an I posted a couple of images on that earlier thread - shot almost into the sun on the beach - and I think they show how well this lens captures and registers light.

Adrian - These images with Leica I 1930 - standard 50mm uncoated Elmar. Posted to the earlier thread, but hope it's worth it again - to show the capabilities of these lenses.

 

Rob<div></div>

Second image with same setup - same place<div></div>

Thanks very much for all of your respunses. I have read that Taylor Taylor hobson experimented with lens surface textures before coatings were found.

 

Rob: thanks for re-posting your photos here. The old Elmar seems to put a little colour into all parts of the picture, and not in an arbitrary way, either. Fascinating!

 

Will have a rummage to see what images I can find from my 1©

 

Adrian.

Wouldn't it be ironic if the "cheaper" glass of old was, because of its "lesser quality," more

oxidation-prone than early Leitz glass?

Gardeners' Question Time on the radio has just given me an idea and I'm off to the garden to bury my Summicrons!

Hmmm - to speed up this process..... Adrian, do you have any cats? Call in to your

gardening program for furter insight!

Do you really think burrying a cat along with the Summicrons would speed up the process ? - Good thinking.

Just trying to be helpful.

John. It occured to me that that's what had been done previously to all the Summicrons I sent back, when trying to buy a good one, and in Bay-speak are only "200 percent perfect". Anyway, the light this afternoon was too good to waste on chasing the neighbour's cat.<div></div>

This must explain why so much artistic Leica photography looks like it was shot through the bottom of an old coke bottle!

 

Wow and this whole time I thought it was the Bokeh stuff.

Agreed. Besides, here in fridgid Vermont, where the ground is already frozen, we need to

put off such burials until the spring melt - which means that the cats are safe for the time

being. And do enjoy the light!

Hmmm - interesting segue. And my reference to cats had more to do with their, um,

digestive by products. But I'm always open to new thinking! (here, kitty kitty!)

Vermont! Robert Frost would have liked this idea.

 

Somerset's waterlogged right now.

Just back in from splitting some wood for the fire - and if I look at your posted photo just

right - I can see, peripherally, the scene of fridgid whiteness out my office window

juxtaposed against the rich warm greens of your image. Very tempting to be in a warmer

place right now. And about your photo - judging from the richness exhibited by your

circa 1930 lens, I'm guessing that it had been buried for quite awhile!

In the Ukraine, somewhere,- at least, that's where it came to me from not so long ago. It's buried in Somerset, now, as I am - figuratively speaking.

 

The picture is from a couple of months ago (the "prepared earlier" is from an ancient British childrens' television program wherein interesting things are made from lavatory-paper tubes etc. but a finished one is always produced that was prepared earlier. So a stiff cat, perhaps....) so it's not that green here, now. It's been a slow Autumn, though, and some leaves are still hanging in there.

Slightly OT, - but in the cause of science, I think.

Your photo brings me back a couple of years - to a scene just outside of Dembidollo in

southwestern Ethiopia. Having stood for a couple of hours in the bed of a Toyota driving

over some pretty rough roads, we stopped for a moment, just as the light was falling over

the trees - just like in your photo. A long day photographing water and medical projects,

and a food distribution center - dog tired and yet this scene before me gave me some

solace, and a reason to raise my Leica once again. I'll need to upload some of these to this

forum soon - maybe over the holidays.

Getting back on topic (if there's anyone still there): is it oxidation that causes the glass surface to form microscopic layers ? It seemss more of a spalding effect than the accumulation of a coating.

Sorry, John - we were writing at the same time. Very much look forward to seeing that.

I have an old lens from a yard-sale purchased Foth Derby that has a very even "oxidation

coating" on its surface.

 

I also just did a little google search, and came up with the following: http://

www.wisner.com/coatings.html and this: http://www.photo.net/bboard/q-and-a-fetch-msg?

msg_id=00CPgZ from this forum. A little conflicting info here - with the forum post's

questions about whether glass can truly oxidize.

 

I'm beginning to infer from all of this that my original intuition might be correct - that

glass with more impurities might be more subject to oxidation.

 

As I type this one of my two cats sits and watches me intently - little does she know how

lucky she is that the ground is frozen!

I don't know if it applies to photography but in painting, landscape seems to be regarded as not relevant, or as escapist and that the problems of the world should be addressed, even if it is just in the style it is painted. That is how it is in the UK, anyway. I don't go for that ; art is a ballance in the world and if it is escapist, it's necessarily so, sometimes.