Cleaning a circular polarizer

[StevieGill]

Hi

I've got some smear marks (accidentally touched with my fingers) on the surface of my Hoya multi-coated circular polarizer that just won't clean off. Though the marks don't seem to affect image quality, as far as I can tell.

I have tried the standard breath and lens tissue approach and I've also tried some lens cleaning fluid (which claims to be suitable for multi-coated surfaces), but with no success.

Any suggestions, or will I just have to live with the marks?

[rob marshall]

I'm only suggesting this, so check first. But I saw a 'sonic' cleaning device last week for spectacles. If you can find one somewhere it might do the job. Have you tried a camera shop? They might have some ideas?

[StevieGill]

I tried one camera shop, they suggested the lens cleaning fluid which they happened to stock. This didn't work, and actually seemed to make the smear a little worse.

[Steaphany]

Be careful how you proceed. I had a $130 filter with a stubborn blemish and attempting to clear it off left the glass surface scratched, and I was using optic cleaning materials.

[Captured]

I think I too may have to go to the camera shop... sadly, I'm pretty sure mine is going to need to be replaced...
and then just have to see what they offer for cleaning filters/lenses so that I can buy that too. I'm hoping I've learned my lesson and will protect/ handle my camera/lens Like it deserves!

[revi]

I'm only suggesting this, so check first. But I saw a 'sonic' cleaning device last week for spectacles. If you can find one somewhere it might do the job. Have you tried a camera shop? They might have some ideas?

I suppose you mean an ultrasonic bath? Jeweller's shops tend to have those as well. Or try your local chemistry lab... (high school/college?)
They are in fairly common use for intensive cleaning of somewhat fragile items, or items with small nooks and crannies.
Use: put your filter in a small vessel with soapy water or another suitable liquid (it's not dry cleaning); put the ensemble in the ultrasonic bath and leave to soak (5-10 min should be ok for a first try; better not put your fingers in the bath while it is in operation)
Just a warning: circular polarizers consist of two layers glued together. I've got NO idea what an ultrasonic bath (or the water) will do to the glue... They layers might come apart, ruining the filter. Perhaps others have experience with those baths for filters (the only filters I cleaned with them were sintered glass, and for those they worked very well indeed )

[Glenn NK]

Further to Revi's comment.

I would be very reluctant to immerse a CPL in any fluid as I suspect the fluid would leak into the space between the two pieces of glass.

And getting it out would be impossible.

[Dave Humphries]

I agree with Glenn,

Once the liquid is between to the two plates, it'll be almost impossible for it to dry out; so immersion is not a sensible option (for a CPL or Vari-ND) and I doubt whether the ultrasonic agitation, which works well in nooks and crannies, will help getting any mark off a flat surface. (It cleans by cavitation)

I have a smallish smear on one pair of my (multi-coated) spectacles and that refuses to budge so I live with it - fortunately it is 'off axis' from where I normally look. No idea how it got there, but sounds like a similar problem.

I have tried several things on it (carefully), but nothing improves it and I am beginning to wonder whether it isn't actually a lack of coating I am seeing - i.e. the original damage* caused a dissolving of one or more layers of the multi-coating, hence attempts to fix merely make it worse (by making it bigger)

* possibly a splash of something fairly acidic or caustic

[rob marshall]

This is probably not the best time to tell you, but I'm always very careful now when handling filters of any kind, after I accidentally damaged one some time ago.

Always keep them in their case when not in use. Be very careful when attaching/detaching from the lens, as it's so easy to drop them - best to do it low to the ground over something soft like your jacket, if you can. Don't walk around with a filter fitted without a lens cap on - even for a short while. If you can't fit a lens cap (eg, slide in filters) then take the filter out.

[Colin Southern]

Once the liquid is between to the two plates, it'll be almost impossible for it to dry out; so immersion is not a sensible option (for a CPL or Vari-ND)

Couldn't agree more.

I doubt whether the ultrasonic agitation, which works well in nooks and crannies, will help getting any mark off a flat surface. (It cleans by cavitation)

I'll tell you now, it won't. (I have one).

Just just a microfibre cloth - it should come off quite easily.

[StevieGill]

Just just a microfibre cloth - it should come off quite easily.

That was what I originally tried, but this didn't remove the smear.

I think maybe the problem is, as an earlier poster pointed out, that the smear is actually damage to the lens coating. As far as I can tell, this doesn't have an adverse effect on images, but I find it's presence annoying

Sounds like I'm going to have to live with it and be more careful with my greasy fingers in future!

[tihsgod]

My cleaner used my BW CPL as a stand for a 1$ coffee mug... 77 mm was just the right size and it really looked a treat on there.

I don't know about smears but unglazed ceramics are quite abrasive I can assure you.

[rpcrowe]

Some filters have a multicoating that is difficult to clean. Hoya originally supplied filters which I had the Devil's own time trying to clean. They have since, I have been told, changed the coating properties to facilitate cleaning. I did not have the same cleaning problems using B+W Schneider filters.

The most difficult thing to clean from my filters seems to be fingerprints, so I try to be extra careful in handling my filters. I use center pinch lens caps and/or OPTECH Hood Hats to keep the front elements of my filters and/or lenses clean.

I store my filters connected together but, I don't use the slim-line filters with only male threads; so all my filters can connect. I keep the stacked filters in a soft microfiber pouch.

Of course, when I said that fingerprints were the most difficult, I forgot about the time my big dog "kissed" the filter with her tongue as I was getting a close-up.

[Dave Humphries]

I'll tell you now, it won't. (I have one).

So you'll know to only use clean liquid, or it 'shot blasts' things instead of cleaning them

I had a colleague who put his specs (glasses) into a tank at college (many years ago) and the lenses came out 'milky' - I suspect it was very dirty and he left it going waaay too long - and of course, the liquid often isn't water.

(Use de-ionised)

[Colin Southern]

So you'll know to only use clean liquid, or it 'shot blasts' things instead of cleaning them

To be honest, I normally use a highly technical solution of warm tap water and dishwashing liquid!

[JK6065]

I found out (today) that Photosol Eclipse CCD cleaning fluid (originally for sensor cleaning) and a microfibre cloth are quite affective to get rid of smear on a CPL or on lenses.
I had similar problems with finger smear on them, and with regular lens cleaning fluid I couldn't get it off.

[StevieGill]

I found out (today) that Photosol Eclipse CCD cleaning fluid (originally for sensor cleaning) and a microfibre cloth are quite affective to get rid of smear on a CPL or on lenses.
I had similar problems with finger smear on them, and with regular lens cleaning fluid I couldn't get it off.

Thanks. I have found product this on Amazon (the reviews are promising), I might give it a try.

[JK6065]

Photosol claims that when combining the eclipse fluid with their PEC*PADs it's safe and ideal to clean lenses and filters. I don't see why a regular microfiber cloth wouldn't do the job, so therefore a used it instead of buying the PEC*PADs. I'll just let you know what the manufacture recommends. Filters and lenses are sensible for scratching and I don't want you to have any trouble due to my advice when I don't follow the recommended way.

[StevieGill]

Photosol claims that when combining the eclipse fluid with their PEC*PADs it's safe and ideal to clean lenses and filters. I don't see why a regular microfiber cloth wouldn't do the job, so therefore a used it instead of buying the PEC*PADs. I'll just let you know what the manufacture recommends. Filters and lenses are sensible for scratching and I don't want you to have any trouble due to my advice when I don't follow the recommended way.

Thanks. I was just going to use a regular microfiber cloth.

[Colin Southern]

Thanks. I was just going to use a regular microfiber cloth.

In all honesty, I haven't found many things that a microfiber cloth and a little "laser breath" can't remove.