I have a latest Elmarit M 90 and used for a few months. The result is quite good. Last week, I was trying to clean the lens since there were some dusts on the back glass. I used brush and the chamois skin to wipe the glass carefully. However, it still made some tiny scratch on the glass. I was very frustrated since I read from some article that Leica lens coating is resistant to scratch. I am not sure what kind of material of procedure should be used to clean the lens.

Thanks

Michael

-- Michael Li (michael6609@hotmail.com), January 15, 2002

Answers

Please buy a E39 UV filter and put it on the lens. You will only scratch the filter , not the lens. Blow off the dust with a blower. If it's finger print or something you can not remove with the blower, use a drop of lens cleaning fluid and remove the finger print with the lens cleaning tissue. Try not to "dry clean" the lens. That's where the scratch comes from. I have the new Leica M 35mm,50mm,90mm. It all works the same way.

Good luck,

Chris

-- Chris Lee (rangefinders@yahoo.com), January 15, 2002.

Michael, scroll down the questions a little to the following:

"How do you clean your lenses?" (Paul Hardy Carter, 2002-01-10)

-- Giles Poilu (giles@monpoilu.icom43.net), January 15, 2002.

Chris:

I don't think a UV filter would have helped the rear element he scratched.

Michael:

As Giles pointed out, a similar version of this question gets asked about every other week, so you may want to check the archives for additional information.

While the new coatings are indeed tough, they can still be scratched. This usually happens because the dust one is trying to wipe off is actually grit or sand, which is harder than the coatings and will scratch them. This is why it is a good idea to first blow or brush off the element in question, and then follow up with GENTILE wiping with a CLEAN lens cloth. (Yes, I know Jay uses his T-shirt, but at least he uses a CLEAN T-shirt!)

The good news for you, is that tiny scratches -- especially those on the rear element -- will have no adverse effect on your images. The bad news, however, is that you have just reduced the re-sale value of your lens by about 15%...

:( Sorry,

-- Jack Flesher (jbflesher@msn.com), January 15, 2002.

Thanks all for the advices.

One more question. I noticed that there is another term, cleaning mark. Is there any difference between cleaning mark and scratch?

-- Michael Li (michael6609@hotmail.com), January 15, 2002.

A cleaning mark is usually residue that is left over by lens cleaner. Sometimes they can be very stubborn to get off. That's why I never use lens cleaning solution on my lenses. If you're going to use lens cleaning solution make sure its 100% volatile (like purified methanol). We use that on the crystal condenser of our $110 000 Coultier Elite FACS so if its good enough for Beckmann it should be good enough for Leitz.

Regards,

-- John. (ouroboros_2001@yahoo.com), January 15, 2002.

A cleaning mark is where the coating has been damaged by repeated cleanings, ususally over a number of years. Cleaning marks were more common before hard coatings were available. Leica lenses from the mid-1960s onward have hard coatings.

-- Douglas Herr (telyt@earthlink.net), January 15, 2002.

What Doug said. Essentially those marks are small but permanent scratches in the coating.

-- Jack Flesher (jbflesher@msn.com), January 15, 2002.

I have bought several lenses with cleaning marks or light scratches. I mixed a solution of water and vinegar and cleaned the lenses properly. The result, no scratches and no cleaning marks. I do not recommend vinegar for the regular cleaning of lenses as it is acidic but it will get any stubborn spots the other cleaners will not touch.

-- John Collier (jbcollier@powersurfr.com), January 15, 2002.

I can understand that vinegar may help to remove the cleaning mark, which other liquid might not. But how come it also remove the scratches? It melt and repair the coating?

-- Michael Li (michael6608@hotmail.com), January 15, 2002.

Lens coatings are essentially VERY thinly deposited metal oxides. In the earlier days (ala Zeiss C lenses) they were mono-coated whereas modern lenses now are usually multi-coated. The coatings are several molecules thick and presence of the H+ in vinegar might be enough to dislodge some of the top of the thin coatings so that you can "push" them around the lens and fill in minor scratches. The lab next door uses a similar trick to repair the ocular coatings on the departments Zeiss Axiophot and Leica DMA. We were alluded to this by the regional rep. for Zeiss who cozies up to our P.I.s for more sales opps. Keen observation John.

-- John. (ouroboros_2001@yahoo.com), January 15, 2002.

John

Thanks for the advice.

-- Michael Li (michael6609@hotmail.com), January 15, 2002.

John:

What is the percentage of vinegar to water? Is it white or cider vinegar?

Thanks,

Ted in Olalla

-- Ted Bayer (tedbayer@harbornet.com), January 15, 2002.

Jack, I use my T-shirt to clean the B+W MRC filters on my lenses, *not* the naked lens elements! However I do use pieces of well- washed 100% cotton underwear rather than microfiber cloths because to me they work better...especially speaking of those thin, shiny microfiber cloths. Also, sorry to contradict, but scratches on a rear element are *more* serious than on the front element, as they affect the resolution whereas front-element scratches basically lower contrast and increase flare. I am speaking, re: rear scratches, of actual scratches. One or two small light marks in the coating will have negligible effect, except as you note, on resale value.

-- Jay (infinitydt@aol.com), January 15, 2002.

After exhaustive comparative analysis I find you should use "some" vinager with "some" water. :-) I have never been particularly precise...say 50/50?

-- John Collier (jbcollier@powersurfr.com), January 15, 2002.

Oh... and I use white vinager as that is what I have on hand.

-- John Collier (jbcollier@powersurfr.com), January 15, 2002.

Jay: I WAS referring to light coating scratches, not actual scratches in the glass... But apparently it is of no concern anyway, as we have all now learned that you can disolve and re-distribute the metal oxide coatings with a simple vinegar and water solution.

-- Jack Flesher (jbflesher@msn.com), January 15, 2002.

Jack,

That's how they "detail" fine scratches on your car's finish too. They get in there with a buffing wheel that "pushes" paint into the scratches. I suppose if you had enough time and a clean microfibre cloth you wouldn't need the vinegar.

Cheers,

From Willy Wonka's Wunderbar World of Excessive Gadgets.

;-)

-- John Chan (ouroboros_2001@yahoo.com), January 15, 2002.

John:

Yeah I knew about car paint, I just had no idea I could re-distribute metal oxide lens coatings with a traditional feminine hygene mix!

-- Jack Flesher (jbflesher@msn.com), January 15, 2002.

Marks on the rear element are FAR worse than those on the front. Scratches on the front may increase flare suscepibility, but the light is usually "diffused" enough not to cause image degradation. Some people put black something in the scratches. Try that on the rear element and you'll get a projection directly to the film.

DO NOT use methanol, it's corrosive. That's why it's not used to oxygenate gasoline, where ethanol, MTBE, ETBE, and TAME (please don't ask) are (except in CA, all being phased out nationwide in favor of ethanol because they mix in all proportions with water: read ground water). Methanol is used in INDY cars because their fuel systems are made of stainless steel. If you must, use ethanol diluted 1:1 with distilled water. Pure ethanol is volatile, which means it evaporates before your done cleaning. Don't use vinegar or any acid; try ammonia.

-- Chris Chen (chrischen@msn.com), January 16, 2002.

Sorry to chop-in. Does anyone has any experience (bad or good) with the ROR lens cleaning liquid? Said to be good but I don't know. If it is really good with no bad effect on the lens, I think I will have a try. Best regards,

-- tom tong (tom.tong@ckh.com.hk), January 16, 2002.

Michael, I have a collapsible 50 cron with scratch marks all over the front element. But the pictures still come out clearer than my contax 50 1.4 mint.

dun worry, just blow it, wipe it and shoot.

-- Travis koh (polar@cyberdude.com), January 16, 2002.

I use Lenspen to clean my Leica and Zeiss lenses. Very effective, lens sparking clean.

I also bring Lenspen when traveling, there is no liquid to spill.

-- martin tai (martin.tai@capcanada.com), January 16, 2002.

Michael, I have learned the hard way that it is better to not wipe at all. Air or a sable brush is probably best. I keep mc UV filters on my lenses (B+W and Heliopan), preferring to clean the filters. In 30 years of photography I can count on one hand the number of times that I have had to clean the rear element; a rear lens cap or camera is always affixed. A product that you might be interested in is Opticlean, used to clean expensive telescope objectives as well as other lenses. Opticlean is applied to the lens, allowed to "set" (where it may stay for protection of the element), and then removed. Opticlean is said to lift all dirt and grit from the lens down to the molecular level without harming any coating. I have NO vested interest in this product. You may contact Opticlean supplier Dantronix in the US at their website:

http://www.dantronix.com/oppolsec.html

-- David (pagedt@chartertn.net), January 16, 2002.