Joao
Negativistic forever
Hi
Is it always possible, by visual inspection, to ascertain that a certain lens is (or is not) coated ? Are there any coatings invisible to the naked eye ?
Thank you
Joao
Is it always possible, by visual inspection, to ascertain that a certain lens is (or is not) coated ? Are there any coatings invisible to the naked eye ?
Thank you
Joao
Roger Hicks
Veteran
Dear Joao,
The old name for coating was 'blooming' and this gives the game away. There is always a faint, coloured 'bloom' on a coated lens.
Modern multicoating is much less clearly coloured than the older single coatings but there is still some colour and the front glass reflects a lot less light than uncoated glass.
A very few, very old lenses can oxidize slightly to create a sort of 'self-coating' effect but this is seldom if ever completely uniform and there may well be a 'rainbow' or 'oil-in-a-puddle' look to the bloom.
Cheers,
R.
The old name for coating was 'blooming' and this gives the game away. There is always a faint, coloured 'bloom' on a coated lens.
Modern multicoating is much less clearly coloured than the older single coatings but there is still some colour and the front glass reflects a lot less light than uncoated glass.
A very few, very old lenses can oxidize slightly to create a sort of 'self-coating' effect but this is seldom if ever completely uniform and there may well be a 'rainbow' or 'oil-in-a-puddle' look to the bloom.
Cheers,
R.
radiocemetery
Well-known
Roger,
I didn't know about the oxidation of glass causing that rainbow look. both of my Summars display this self coating, but I have a 1937 Schnieder Xenon on a Certo Dollina that is water clear and nearly unmarked. I wonder if the glass formulation has some effect on this.
Steve
I didn't know about the oxidation of glass causing that rainbow look. both of my Summars display this self coating, but I have a 1937 Schnieder Xenon on a Certo Dollina that is water clear and nearly unmarked. I wonder if the glass formulation has some effect on this.
Steve
Muggins
Junk magnet
Roger,
I have a Meyer-Goertz Trioplan showing exactly such bloom. When I first stripped the camera two years or so ago under the dirt (and it was disgusting - it looked as though it had been kept in a henhouse!) the lens was a very faint purple shade, and I thought I'd destroyed a delicate early coating before I'd realised it was there.
Looking at it recently it now displays a lovely "oily puddle" bloom.
So... When I get a parts shutter for a proper repair job, should I clean this or leave it as it is? If it IS oil I'd like rid of it, but presumably if it is surface oxidation I will wreck the front element trying to remove it?
Hope you can clear those up for me,
Adrian
Roger Hicks
Veteran
Steve: Yes, the glass type makes an enormous difference: I've seen 100-year-old (and older) lenses water-clear. Maybe storage conditions matter too: I don't know enough to be able to say.
Adrian: Caliope OptiClean (paint on/dry/peel) will remove oil (if that's what it is) but not, I think, oxidation. Either way it won't hurt the lens (at least, it's never harmed anything I've tried, and they guarantee it). That's what I'd go for.
Cheers,
Roger
Adrian: Caliope OptiClean (paint on/dry/peel) will remove oil (if that's what it is) but not, I think, oxidation. Either way it won't hurt the lens (at least, it's never harmed anything I've tried, and they guarantee it). That's what I'd go for.
Cheers,
Roger
Joao
Negativistic forever
As usual, I got the information I wanted!
Many thanks again
Joao
Many thanks again
Joao
Roger Hicks
Veteran
Sorry about this. I just checked Caliope's list of suppliers and can't seem to get a good link. Caliope are closed now, but I'd like to know too -- I don't have much left -- and as their website is shown as updated in 2008 I assume they're still in business.
It's a US product repackaged in small quantities by Caliope in the UK; apparently, some members of the US press reckoned it was too hard for US customers to understand the instructions -- a bit harsh, I'd say.
I'll try calling them tomorrow. It takes maybe 1 ml to clean a lens surface...
Cheers,
(and apologies once again)
R.
Muggins
Junk magnet
If you can find supply details for an affordable amount, it would be much appreciated!
Adrian
Adrian
V
varjag
Guest
If I may chime in, new Zeiss cleaning kit does a wonderful job, better than everything else I tried.