[Canada_Rockies]

Well, isopropanol is an alcohol, but don't drink it. I don't know exactly what would happen, but probably not good for liver etc. If you mean ethanol I suppose one might use it instead of isopropanol. I don't know why isopropanol is better, but it is often recommended for cleaning any glass...and I think it is cheap to produce.

I've been using Kodak lens paper and lens solutions for I cannot count how many years. No damage to any of them. Some news photographers have used a tie and spittle successfully, but I have never had the guts to do that.

im a lenspen user also, first brush the particles with lenspen brush and then the lenspen "magic" Sometimes i breath to the lens to see result or get mild moisture to improve the cleaning. After i bought lenspen 2 years ago, i never had to use any chemical to my lenses.

[marlon]

For starters, how does smears get on the lens. Please do not fry bacon on it!!
I never had the need to clean my front elements, but you guys sure have me thinking with all this alchohol and cleaning fluid debates here.
Im sure a good dishwashing liquid (heavily diluted) should be ok? If dishwashing liquid left anything behind, then how safe would it be to eat off plates after they have been washed

[séamuis]

Seamuis, do you know what's in the formula MC?
Sort of funny, on one of the links you gave the advertiesment for forumla MC says "Approved and used on the space shuttle!". Is that supposed to be some sort of reinsurance that it is safe to use?

no I don't know whats in it, nor do I care if NASA uses it. all I know is that it works, and works very well. I have had no damage of any kind to any of my lenses using this product. and as far as im concerned, if there is a product that makes cleaning lenses quick and easy without the hassle of tracking down pure isopropyl and diluting and what not then im all for it.

a quick puff of air from a blower, kodak lens tissue, one drop of Formula MC, and about 45 seconds of my time eqauls a clean, smudge free lens. I dont have to worry about some lens pen or other brush scratching my front element. or having some inferior alcohol or other substance leaving water marks or anything else that can over time eat away at the coating. its quick, simple and cheap.

I again recommend Formula MC.

[Spongefingers]

ROR (Residual Oil Remover) is good stuff, I use this on my lenses with a microfibre lens cloth. It does a lovely job, but it can sometimes require quite a bit of rubbing to get the finish perfect.
I use it on my spectacles too - with excellent results.

[maxwell1295]

.....any lens cleaning solution can be used. If you get one designed for eyeglasses in a spritzer bottle, don't spray the lens directly, as you can get fluid inside the lens. Spray the cloth, and then wipe the lens, again in a circular motion with the damp fabric, and then dry it with a dry end of the material.

This is what I do. I buy the small enough to fit in the camera bag bottles from Walmart's eyeglass section.

[Wheatfield]

For starters, how does smears get on the lens. Please do not fry bacon on it!!
I never had the need to clean my front elements, but you guys sure have me thinking with all this alchohol and cleaning fluid debates here.
Im sure a good dishwashing liquid (heavily diluted) should be ok? If dishwashing liquid left anything behind, then how safe would it be to eat off plates after they have been washed

Smears get on lenses when you use them rather than baby them. Stuff happens. Pentax coatings are tough enough to withstand a cigarette being butted out on the glass without marring.
They can be cleaned without overly worrying about damage, and they can be used without worry of damage under reasonable conditions.

There is a difference between something being safe to eat, and being non residual.
I could rub a freshly cooked steak on a lens, the residue would be safe to eat, but not so nice for making pictures through.
Most any solvent can be used for cleaning a lens. Lighter fluid can be used sparingly, as can acetone (ROR is made from this chemical IIRC), as well as water, pure or with a detergent of some sort, as can alcohol.
The coatings are not going to come off of the lens unless they are rubbed off. Damage to lenses is best accomplished by cleaning them dry rather than wet, since it is easier to abrade the surface with a dry cloth than a wet one.
Cleaning fluids should always be introduced on a cloth rather than directly to the lens to prevent it from flowing behind the outer element.

Your lenses are tougher than many people think.
The best cleaning cloth I've found are microfibre cleaning cloths, often available fairly cheaply in the cleaning products secion of Wal-Mart and their ilk.
Failing that, and a very close second is regular cotton T-Shirt material (old T-Shirts are best). just make sure that the fabric is freshly laundered and has been washed often enough to take any sizings out of the material, perhaps 3 or 4 times, and that they don't have the common T-Shirt dreck advertising for various products.
The best cleaning solution you can get is your breath.

If the lens has particles of stuff, brush them off with the T-Shirt, then breath on the lens and wipe it with circular motions. This will probably be enough. If it isn't, then any lens cleaning solution can be used. If you get one designed for eyeglasses in a spritzer bottle, don't spray the lens directly, as you can get fluid inside the lens. Spray the cloth, and then wipe the lens, again in a circular motion with the damp fabric, and then dry it with a dry end of the material.

There speaks a man who is not fooled by false prophets or advertisers psycho babble.

[creampuff]

Use what the optical factories use, isopropyl alcohol.
Cheap, no added stuff, non acidic or alkaline, wipes clean in seconds.

As to Lenspen, it works for awhile until the tip accumulates whatever grease, oil or grit. There are lots of people who swear off Lenspen for inadvertently scratching their lens/filters due to embedded grit on the tip.

Acetone is reactive to paint and plastics so it should be used with caution.

[marcdsgn]

What ever you use, do not tumble-dry!

I'll never make that mistake again!

[jamesm007]

There speaks a man who is not fooled by false prophets or advertisers psycho babble.

I second that. I have used Kodak paper, its OK not so Ok on Hoya filters but "The best cleaning cloth I've found are microfiber cleaning cloths" for 100% sure. And you can wash them when dirty so you can just keep using them, there great. If the spot is stubborn a drop of lens solution on the microfiber cloth will do it, and thats after you blow your lens with something to make sure no particles are on it. I went for a long time ignoring the microfiber claims, big mistake they even wipe a Hoya filter clean with just your breath in seconds, try that with Kodak paper (which I own).

[wildman]

I need to give my lens a good clean as there are some smears that just don't come off with a dry lens cloth, what should I use ? I tried a search but found nothing so don't flame me for not searching first

Take a look at this:

Tele Vue Optics Article Page

It's the method I have used for the last forty years with all of my optics with no problems. I use Isopropyl Alchhol and clean old T shirts. Just make sure you have all solid matter off of glass first.

[rogerstg]

FWIW, ammonia products (Windex) dissolve many optical coatings. Not sure how the affect Pentax coatings, but I would not take the chance.

[patrickt]

Out in the field, I use a lenspen. Actually, I've used one on one of my lenses just once. I don't eat potato chips while I'm taking photos but some apparently do.

Perhaps once a year, I'll clean each lens at home with a liquid, I usually opt for a lens cleaning solution, and a microfibre cloth. I brush the lens lightly before anything touches it, then I put some liquid on the cloth, and rub lightly. It's always worked for me.

"Smears get on lenses when you use them rather than baby them." I disagree. My camera is at my side, no case, every time I leave my home. If I'm going to pay my phone bill I have the camera. You never know. I take photos in light rain, high wind, construction sites, and open-air markets. But, if I'm not actually taking a picture I have a lens cap on the lens. Always.

[Wheatfield]

I second that. I have used Kodak paper, its OK not so Ok on Hoya filters but "The best cleaning cloth I've found are microfiber cleaning cloths" for 100% sure. And you can wash them when dirty so you can just keep using them, there great. If the spot is stubborn a drop of lens solution on the microfiber cloth will do it, and thats after you blow your lens with something to make sure no particles are on it. I went for a long time ignoring the microfiber claims, big mistake they even wipe a Hoya filter clean with just your breath in seconds, try that with Kodak paper (which I own).

Hoya filters are famous for being hard to clean and easy to smear.
Patrickt, I don't know what you are disagreeing with, a lens that is capped unless a picture is being taken is a lens that is being babied, and is unlikely to attract dust, smears, or, unfortunately, good pictures, since it is hard to be spontaneous when you have to take the cap off the lens every time you are going to use it.