Lens Cleaning: Keeping fog or Losing a coating?
I own a Summicron 50mm lens which currently needs a cleaning job. However, I'm so worried about losing the coating of the lens by the cleaning process in order to get rid of the fog.
I've been told by the person at the repair shop that my lens, which is old enough will likely lose the coating a bit in the cleaning process since the coating has already been slowing decaying, and there's nothing I can do about it.
Since it's not a cheap lens, I need to have a little sanity check here: Is it normal and acceptable to take this as a choice? Or should I cancel the cleaning and stick to the lens in the corrent condition with the fog and just keep using it until the fog really starts to bother me and ruin the image quality?
What are your experiences on making your decisions for the lens cleaning when there's obviously going to be some loss?
When you clean ANY lens, with ANY method, you WILL lose "some of the coating". Anything that comes in contact with the coating, including liquids, will abrade and remove some of it. In the interest of preservation - NOT cleaning the lens , it is good advice to mount a filter on the lens - "UV" or "Skylight" or some other such "clear filter" - and leave it there. You can go crazy cleaning the filter - if you like, and just replace the filter after it is completely opaque.
Originally Posted by firecracker
In a different life, I was a Quality Assurance Specialist in a large company producing sophisticated optical systems. We were allowed ONE method to clean lenses: Distilled water and surgical cotton -- with NO pressure. If whatever foreign material could not be removed, the lens was sent to Technicians SPECIALIZING in lens cleaning. We had one really unfortunate instance involving the use of a common pencil eraser - I've never seen anyone fired so quickly in my life.
However, you mention "fog". What is usually seen on the outside of the lens is dust. Are you sure that "fog" is on an external lens surface? If it is internal, it is probably fungus, and your one hope is to have it disassembled, cleaned and if necessary, re-coated.... not an inexpensive task.
Your best bet there would be to contact Schneider USA, and talk to them.
Ed Sukach, FFP.
Opticlean. Pure magic. www.caliope.co.uk.
VERY interesting. Never heard of anything like this before. Thanks, Roger.
Originally Posted by Roger Hicks
(I love the pic of the old ULF camera on their website. Forget where I saw that before.)
While this may be true of early coatings used in the 50's and 60's, todays coatings are very hard. However, I agree that more lenses have be ruined by overcleaning than by not cleaning them. Kodak makes a good lens clearer that is safe to use.
Originally Posted by Ed Sukach
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I'm presuming this fog is on internal lens elements.
Does the haze inside the lens actually cause any deterioration of the image? If it does, I'd opt for a good professional technician to disassemble, clean, lube and adjust the lens right now.
If it's not an image quality issue, I'd just keep on using the lens as is until it absolutely had to be cleaned.
Of course, if it's fungus you had best go ahead and get it taken care of immediately.
"Todays" coatings ARE much harder. Any contact will still degrade the coating, granted, to a lesser degree than before, but it is still VERY advisable NOT to clean the lens if at all possible.
Originally Posted by Gerald Koch
I remember one instance, where I found a Multi-coated Heliopan filter, in a "Bargain Box", complete with a price sticker ($15) smack-dab in the middle of the glass (and coating). A helpful (at least well-meaning) clerk proceeded to remove the offending sticker ... and *grind away* at the adhesive residue with a dry paper towel.
I think it took me about an hour to un-clench my teeth.
There is an extensive sub-market for "miracle lens cleaning tissues/ fluids". I know not what course of action others may take, but as for me ... surgical cotton, distilled water, and a nearly complete lack of pressure ... once a year, if I cannot avoid it. I consider NOTHING to be "safe".
Ed Sukach, FFP.
Thanks for your comments here. I should've been more clear on the description of the lens and its condition.
The lens is a collapsible 50mm Summicron from the 50's, and the problem is the inside.
The person/technician at this well-known repair shop specialized in repairing old used Leica products in Tokyo told me that there are at least a few elements that have "something." What he has so far noticed are:
A few very thin cleaning marks from the previous service,
and the decay of the coating that's peeling off,
which make the the lens look foggy or hazy.
The outside elements both front and rear are clean.
And he didn't mention about any signs of the fungus, which I asked because that's what I'm concerned the most, because Japan is a country with very humid summer.
So, basically if he does the normal cleaning on these elements, that will remove the coating a bit (or should I say, the coating will naturally come off due to its old age). He cannot do any re-coating. His shop doesn't offer that service.
But since it's an old vintage lens, I'm not sure if the lens elements can be re-coated. Or that might change the quality drastically or something.
So, what do you think?
I use an old (uncoated) Tessar on my 4x5. The lack of a coating hasn't stopped me at all.
Originally Posted by firecracker
OTOH, if it ain't broke, why fix it! You've described what the lens looks like but... what do the images look like? If none of this stuff affects the images, why not just leave well enough alone?
Thanks for the comment/advice. My concern is about the rapid growth of fungus in the humid environment. Naturally Japan is a country famously known for that, and many people use drying cabinets, etc to prevent anything to grow in their photo equipment.
Originally Posted by bob01721
I know sometimes it's ovekill to think about storing the photo equipment properly, but this is not the case. It's just too chancy to leave and/or use them just like how I used to.
So, where do I compromise when I see something inside the lens and it seems it's growing? I'm sure I need to clean it off. But will the lens cleaning leave any spots on the coating(s)? Are the spots going to be very visible/noticable? How much do they affect the images in both B&W and color? Will I be able to see them that in the enlargements like 16x20"?
The last time I used that Summicron lens was a while ago, and because now I live in a different place with different light, and using different enlarging equipment for my photos, I cannot really compare the results so critically.