Cleaning scope lens?

[Tommie]

In the 1990’s I bought and used one of those lens cleaning pens. You’ve all seen them: retractible bristles at one end and a soft rubber cup at the other end. Despite following manufacturer’s instructions, the objective lens of a vintage Leupold 24X ended up with permanent marks. I’ve been afraid to touch a scope lens ever since. Is there generally agreed upon technique for cleaning scope glass?

 

[Lesloan]

In the 1990’s I bought and used one of those lens cleaning pens. You’ve all seen them: retractible bristles at one end and a soft rubber cup at the other end. Despite following manufacturer’s instructions, the objective lens of a vintage Leupold 24X ended up with permanent marks. I’ve been afraid to touch a scope lens ever since. Is there generally agreed upon technique for cleaning scope glass?

 

[Lesloan]

I'll be following this thread myself. I hate cleaning scope lenses 'cuz I don't want to damage the coating. The only thing I use the "pen" for is the brush, to get any loose dust off. Then I use a lens cleaning spray and a soft microsoft cloth to finish up. But I'm still not comfortable doing it, so tend to let my lenses get kinda dusty between cleanings.

 

[golong]

I blow mine off with canned air then hit them with a lens wipe. Have not damaged one yet. May be skill, may be luck.

I have the camera kit type stuff you are referring to. I don't use them on scopes because of all the dirt that gets stuck in the threads. I simply don't see how a brush or puff blower will get all of that out of there.

 

[K22]

I use a soft bristle 1" polyester/nylon blend paint brush dedicated to only cleaning scope lens. I use a soft touch with the lens directed downward so any debris tends to fall out while I gently brush. First I brush the threads then the lens very carefully. I finish with a lens cloth but before I do I make sure that any debris has been removed. I've never scratched a lens using this method but I go slow and careful.

Despite having lens caps I still manage to get foreign debris on the lens because I varmint / predator hunt a lot. I only clean when necessary - this is something you definitely do not want to over do or do unless necessary.

The rubber cup you mentioned could be the culprit if you used it on the lens - it may have ground some debris into the lens. Also be careful using any liquid lens sprays on scope lens since they are coated. If you have to use liquid to remove some foreign material use a lint free clean cloth dampened with warm water after use brushed the lens clear of debris - again use a soft touch.

 

[ronemus]

There are microfiber cloths and lens papers that are specifically intended for lens cleaning and they do not scratch lenses or coatings; they're available in eyeglass shops and photography shops. The same venues will have cleaning liquids that are water, isopropyl alcohol, and a bit of detergent. Apply a bit of liquid to a cloth or paper to wipe the lens, and then wipe off the remaining liquid with a dry cloth. This will not damage lenses are assemblies (scopes, binoculars, etc.) and can also be used for computer and phone screens.

 

[moondog]

From Zeiss, LITE air to blow off the dust.
Drop of Dawn with water in a spray bottle to get any smudges and remaining dirt off. Follow up with a clean water spray. Lite air and follow up with microfiber lens cloth.

 

[phlegm]

I blow mine off with canned air then hit them with a lens wipe. Have not damaged one yet. May be skill, may be luck.

I have the camera kit type stuff you are referring to. I don't use them on scopes because of all the dirt that gets stuck in the threads. I simply don't see how a brush or puff blower will get all of that out of there.

Be very cautious with the canned air. It's been known to crack objectives because of the drastic temperature shift from cold air.

It's better to use a puffer like the one in this kit:

Rinsing with rubbing alcohol is also a good way to remove large or abrasive debris before wiping.

 

[jepp2]

Is there generally agreed upon technique for cleaning scope glass?

Scope glass presents a slightly different challenge, since the presence of gun cleaning solvents and oil exists. So I approach them with caution. I frequently will purchase used scopes in good condition, since there is excellent cost savings. In general, I follow the cleaning guidelines for cleaning camera lenses. The most thorough I have found:

https://www.borrowlenses.com/blog/how-to-clean-a-camera-lens/

That said, I add the following rules when cleaning scope glass:
1. I assume if there are dots present, that could be something that can contaminate whatever I use to remove it. So reusing a microfiber towel, lens brush, lens pen etc is avoided.
2. I use a hurricane blower to remove the loose dust. If the lens doesn't show any dots, I will use a quality lens brush, then blow again.
3. The only lens cleaning solution I have found that will clean the lens, and not leave a residue mark behind is ROR (residual oil remover). I use the spray bottle, and lightly "mist" a cotton ball. Make sure the cotton balls are 100% cotton. Then I follow it with 2 additional cotton balls in sequence to remove the ROR before it dries. Avoid touching the surface of the ball that will contact the lens, as skin oil can transfer. I tried about every other lens cleaning solutions recommended before I found ROR.

Caution: it is covered in article I provided the link to, but never apply your lens cleaning solution directly to the scope glass!

I have cleaned up some pretty grungy scope glass, but luckily nobody used the shirt tail method to clean them (and wound up scratching them).

 

[Magnett]

Be very cautious with the canned air. It's been known to crack objectives because of the drastic temperature shift from cold air.

It's better to use a puffer like the one in this kit:

Rinsing with rubbing alcohol is also a good way to remove large or abrasive debris before wiping.

Rubbing alcohol is very bad for lens coatings!

 

[centershot]

Do not use a paper product!

 

[shoobe01]

Do not use a paper product!

Untrue. Some paper products, and many more back before the mid-70s, had fairly rough pulp fibers which could scratch up the less-robust coatings on glasses and the like. Today, even typical paper towels are pretty soft.

I have cleaned a LOT of lenses. More night vision than scopes, but plenty of thermals, scopes, RDSs, lasers and LRFs, camera lenses, scanner beds, etc. Many of these (thermals are gallium glass!) are weird, crazy expensive, and often very dirty as I am servicing stuff others messed up.

I clean (and this acquired from professionals doing the same in other optical contexts who told me) this way:

• Inspect. If really big chunks, blow off with a squeezy blower. Never canned air, never shop air. Do this with the lens pointed down, or at least sideways, so you aren't fighting gravity.
• Lens up, spray with Windex, or similar. The little spray bottle the optometrist gives you are good also, but not so much better I bother to buy any. Do not use alcohol or other solvents as they can mess with not just coatings, but seals.
• Using a /disposable/ optical wipe, start in the middle, and wipe in a spiral (ish), working your way from the center to the edges. You don't look through the very edge and that grabs the worst grit and stuff, so never start in the edges even if they are clearly the dirtiest.
• Like window washing, unless it is very dirty and you need to flush clean first, continue wiping until the liquid evaporates away. You'll end up streak free then!
• Throw away the wipe. If you need to clean again (visible spots, smears, etc) start over. New wipe, more liquid. Dirty lenses are common; not much environmental rain, etc. will leave residue, and you have to clean 2-3x.
• If it's a sacrificial cover/filter/lens, take it off, clean it off the device, and don't forget to clean both sides.
• Don't forget to clean nearby accessories. Blow off killflashes, clean the lens cap and make sure it's dry (and the seals and corners of everything are dry) before closing it up again. Caps can use brushes etc but avoid oil.

One big trick is much as discussions of cleaning rods and bore guides: the problem most run into is less the materials than the procedure. If you have a perfect cleaning wipe or brush, but you re-use it, there's dirt on there. Assume all dirt is abrasive because much off it is.


Best wipes: https://www.amazon.com/Kimtech-Science-KimWipes-Delicate-Wipers/dp/B0013HT2QW/ref=redir_mobile_desktop?_encoding=UTF8&aaxitk=KVvzPWjB2.xc5clfADl8ew&hsa_cr_id=4144551510001&ref_=sb_s_sparkle_sl

For field use, these work as wet and wipe in one, also are slightly anti-fog etc so useful for that: https://www.amazon.com/gp/product/B000GULTY0/?tag=accuratescom-20

Best blower: https://www.amazon.com/dp/B00017LSPI/?tag=accuratescom-20


For things that are cheaper, more likely to get dirty/scratched every day anyway, etc. like the RDS on my pistol, I use a squeeze blower with brush, and do a quick blow and wipe before each time I put it on.

I have this small brush / blower but got it for free, no idea if there are better ones:
https://www.amazon.com/dp/B00LV01BT2/?tag=accuratescom-20

Only when it gets rained on or something do I follow the full procedure above.

 

[phlegm]

Rubbing alcohol is very bad for lens coatings!

This article recommends isopropyl alcohol, which is the more concentrated version of rubbing alcohol.

https://www.edmundoptics.com/knowledge-center/application-notes/optics/cleaning-optics

 

[jds holler]

Soooo, I guess nobody uses their shirt-tail any more?? jd

 

[shoobe01]

This article recommends isopropyl alcohol, which is the more concentrated version of rubbing alcohol.

https://www.edmundoptics.com/knowledge-center/application-notes/optics/cleaning-optics

Rubbing alcohol should be used for nothing but the exterior of people. It's alcohol (types vary) with lots of water. Also maybe other things.

Denatured Alcohol is what pure ethanol, as sold in hardware stores in the US, is called. It's a pretty good degreaser, etc.

But... it is a very good degreaser. It ALL oils, even those inside materials like rubber. So I would still not clean a mounted optic with alcohol. I've heard others who do this a lot say the same, and have seen damaged and destroyed optics from seals drying out.

Also, that link itself has lots of caveats. It ends in:

If you are unsure about the type of optic that you have or the reactivity of your optical substrate or coating, then using De-Ionized Water and a little bit of dish soap is the safest way to make sure the optic is not damaged by harsh chemicals.​

Dish soap (aside from being VERY sudsy, so you must use almost none, and rinse a lot) also has to be carefully selected these days as they have odd additives as well, some have micro-abrasives. If you use soap, choose carefully.

 

[SEGARE]

I've been using Dawn for years and haven't damaged anything. It's reassuring to see that no less than Zeiss concurs.

 

[Tommie]

In the 1990’s I bought and used one of those lens cleaning pens. You’ve all seen them: retractible bristles at one end and a soft rubber cup at the other end. Despite following manufacturer’s instructions, the objective lens of a vintage Leupold 24X ended up with permanent marks. I’ve been afraid to touch a scope lens ever since. Is there generally agreed upon technique for cleaning scope glass?

To follow up on my original question, I contacted Burris. Their response:

We would suggest using a cotton swab and rubbing alcohol on the lenses.

 

[phlegm]

Rubbing alcohol should be used for nothing but the exterior of people. It's alcohol (types vary) with lots of water. Also maybe other things.

Denatured Alcohol is what pure ethanol, as sold in hardware stores in the US, is called. It's a pretty good degreaser, etc.

But... it is a very good degreaser. It ALL oils, even those inside materials like rubber. So I would still not clean a mounted optic with alcohol. I've heard others who do this a lot say the same, and have seen damaged and destroyed optics from seals drying out.

Also, that link itself has lots of caveats. It ends in:

If you are unsure about the type of optic that you have or the reactivity of your optical substrate or coating, then using De-Ionized Water and a little bit of dish soap is the safest way to make sure the optic is not damaged by harsh chemicals.​

Dish soap (aside from being VERY sudsy, so you must use almost none, and rinse a lot) also has to be carefully selected these days as they have odd additives as well, some have micro-abrasives. If you use soap, choose carefully.

I guess some manufacturers are comfortable with it being on their lenses. The link below shows this around the :52 second mark.

To your point, lube/grease does need to be on some places like o-rings. I wouldn't clean with alcohol if it has the potential of drying that out.

 

[BenPerfected]

Or use & carry the small lens cleaning packs.
Ben

 

[jds holler]

The Nightforce add is kinda off topic, but I love it. And the guitar. jd