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smearing problems when cleaning lenses


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I wonder if anyone has similar problems to mine with smearing occurring when trying to clean telescope or binocular optics.  It's usually a fairly tenuous smearing, but quite noticeable.  The larger the lens, the more it happens.  So, not quite as much with eyepieces, but always with objectives.  (Granted, it probably doesn't matter as much with objectives.)

I've thought it was because my microfiber cloth became contaminated, so I cleaned it.  I thought it was because I cleaned the microfiber cloth in the laundry, and needed to hand clean it.  I thought it was my DIY multicoated lens cleaning solution of 25% isopropyl alcohol and 75% distilled water, that one ingredient or the other, or both, had become contaminated, so I only used my breath.  I used cotton balls fresh from the package.  I used a brand new microfiber cloth.  No matter what I do, all of the above still produces a lot of smearing across the lens every time I clean.  Cotton balls don't do it as much, but leave stubborn fiber bits on the lens.  My hands aren't dirty.

There are those multicoated lens cleaning kits you can purchase, but somehow I doubt they'd work any better considering all I've tried.  I have noticed a good while after cleaning, the smearing doesn't seem quite so noticeable.  Is this unavoidable to get a lot of smearing when cleaning?  Or maybe I am just worried about it too much?

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Hello Mizar. I have had this problem with camera lenses caused by grease deposits and found that normal cleaning just spread it into a thinner layer, the one thing that did shift it was a lens cleaning pen but not sure if i would want to risk it on a telescope objective.

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Hello Mizar. I have had this problem with camera lenses caused by grease deposits and found that normal cleaning just spread it into a thinner layer, the one thing that did shift it was a lens cleaning pen but not sure if i would want to risk it on a telescope objective.

I think you're right, it would have to be designed for multicoated lenses.

The cleaning solution sounds helpful, but it seems to only be designed for camera lenses.  It would be advisable that it be designed for multicoated telescope optics.

The cleaning pads at least mention use on telescopes, so they may have advantages over cotton balls and conventional microfiber cloths.  :smiley:

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These microfibre cloths: if they are meant for cleaning spectacles it may be that they are impregnated with anti-misting compounds. If the washing machine load you washed the first one in had fabric conditioner added, that will add a layer of grease to the contents (that's what makes clothes feel "fluffier").

I'd suggest trying some soft toilet tissue. The kind without any added balms or perfumes. Because of the sensitive areas it's used on :shocked: , it is usually pretty inert material. Just don't rub too hard: paper fibres like the fibres in cotton wool are abrasive to some small extent.

Generally I find that on  the few occasions I've cleaned my optics, there is what looks like a film left on the surface - you can see the "rainbow colours". But this is just due to the residual water, Once that evaporates off, the surface is quite clean.

Alternatively, it may simply be that the pollutants around where you live aren't soluble in IPA. Maybe ask at a local photographic store, or add a drop (no more) of detergent to your mix. Then use a final rinse of water without any added cleaners.

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This is why I always try to refrain from cleaning lenses. Anything greasy can end up smearing across all the lens.

Get some Baader Wonder fluid and cloth. A couple of drops on the cloth not on the lens (to prevent it getting "wicked" between the lens elements) . Once thats done, then a gentle polish by "haaa-ing" on the  lens with your breath and using the cloth.

Job jobbed

http://www.firstlightoptics.com/misc/baader-optical-wonder-fluid.html

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I use iso alcohol and sometimes acetone for stubborn grease marks. as above though just breath and a clean cloth to finish works well too to finish off. as long ass there's no solids on the surfaces you are unlikely to damage the coatings.

I also agree that cleaning things if often not beneficial in real terms but does make them looks cosmetically nicer. often the only time I clean optics is just before I sell them as people seem to want nice clean sparkly surfaces.

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+ 1 for Baader Wonder Fluid! Excellent stuff.

+2 great stuff and the micro fibre cloth. 

If you mess up cleaning a lens and mark the coatings the cost of replacement is huge compared with the cost of the Baader cleaning kit.

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Water and just a touch of mild soap. Use pure cotton, wipe with water to get rid of the soap and then wipe it dry. No film left, no coating leaving the surface. I clean my optics regularly and have never seen any degradation at all. Camera lenses, scopes, mirrors.

/per

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How do you know you have smearing? I'll bet that you check by looking at the lens from the 'outside.' Do you see anything when you look through the optics? Again I'll bet that the answer is 'no.'

OK, anything that you see from the outside is reflected from the objective. What percentage of the incident light is that? One percent? Does it go down the telescope? No. Does it matter? How can it?

When you have a professionally cleaned optic with no apparent smearing can you tell any difference whatever from the same objective a few months later when you've had to clean it yourself? (I'm talking about looking through it, not at it.) I know the answer. You cannot.

The 'oil slick' effect is of no significance whatever and we should all have the mental discipline to ignore it entirely. We should look through our optics and not at them. The professionals would never give this kind of thing a second of their attention.

Olly

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  • 4 years later...

There are a limited number of materials that fulfil the requirements of lens coatings. ALL lenses use these materials, the most important is that the last ( outer ) coating is sufficiently hard to resist scratching. This applies to all lenses so any proprietary cleaning solution intended for "lenses" will be safe for the exposed surfaces of ALL lenses, camera, telescope, binoculars, and specs.

Nigel

 

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