Is it okay to clean the inside surfaces of a polarizing filter?

[Jerry Thirsty]

I was cleaning a polarizing filter the other day and after doing both sides realized that there was a haze on the inside. Assuming I can get it apart, is it safe to clean the inside surfaces? Or is it like a first surface mirror, where trying to clean it will remove the coating?

thanks,
Jerry

 

[David A. Goldfarb]

They're usually cemented--a sheet of polarizing film between two sheets of glass--so it wouldn't be easy to take apart. You should probably just replace it. Is it a very old filter?

 

[Jerry Thirsty]

It might be 10 years old or so.

But I was always under the impression that a polarizer has two layers of polarizing material. One in the half that screws into the camera lens, and one in the rotating half. If each piece of polarizer material is sandwiched between two pieces of glass that would be best, because I could clean the inside glass faces without touching the polarizer material. If it's just something adhered to the inside of the glass, then maybe cleaning would wreck it.

The glass that rotates is held in by a threaded ring, so I should be able to get that one out with a lens spanner. Once that's out the inside surface of the other piece of glass will be exposed.

Maybe I'll just have to get an appropriate spanner and try it.

 

[colivet]

Get a new polarizer. That one is gone. The filter should look like one solid piece of glass. No, it is not two pieces of foil, just one that rotates on a ring. If your is foggy or separated it is gone...

 

[Trask]

Hey, if it's shot, it's shot -- so if it were me, I'd go ahead and take it apart to clean it -- kind of a Mr. Science experiment.

 

[Bob F.]

But I was always under the impression that a polarizer has two layers of polarizing material. One in the half that screws into the camera lens, and one in the rotating half. If each piece of polarizer material is sandwiched between two pieces of glass that would be best, because I could clean the inside glass faces without touching the polarizer material. If it's just something adhered to the inside of the glass, then maybe cleaning would wreck it.

Nope. I think you are getting confused by "cross polarization" in which you rotate one polariser in relation to another to get a neutral density effect or use a polariser on the lens and another on the light source for assorted effects such as looking at stress patterns in glass and plastics etc.

There is only one polarising screen in a filter.

Cheers, Bob.

 

[cowanw]

I was cleaning a polarizing filter the other day and after doing both sides realized that there was a haze on the inside. Assuming I can get it apart, is it safe to clean the inside surfaces? Or is it like a first surface mirror, where trying to clean it will remove the coating?

thanks,
Jerry

I have had my B+W kaseman polariser shake apart at the retaining ring. there are 2 elements and you can take them apart and clean them.

 

[Ole]

B+W Kasemann filters should be cemented together, according to their advertisments. The glass is ground, polished on the inner sides, then cemented in the "sandwich", and the final package is then ground to optical flatness. They shouldn't come apart, that's why they're more expensive than many others!

Circular polarisers have two layers: A polarising layer, and a quarte-wave plate that removes the polarisation. Linear polarisers have only one layer of polarising film.

 

[cowanw]

B+W Kasemann filters should be cemented together, according to their advertisments. The glass is ground, polished on the inner sides, then cemented in the "sandwich", and the final package is then ground to optical flatness. They shouldn't come apart, that's why they're more expensive than many others!

Circular polarisers have two layers: A polarising layer, and a quarte-wave plate that removes the polarisation. Linear polarisers have only one layer of polarising film.

Yes I have circular polarisers.
And dont you hate it when the advertisments don't hold up to the real world.
actually the outer rotating plate on the Kasemann circular polarizer is held in with a screw in ring just like any other filter.
Bill

 

[David A. Goldfarb]

I have a Linhof polarizer in a 70mm drop-in mount that I purchased second-hand, so I don't know if it's a Kaesemann, but the filter is mounted in a ring, which is glued into the 70mm mount, and that glue started melting into an ugly mess this summer. I bought it as part of a lot of other filters, so it wasn't too expensive to me, but this is like a $350 filter, if you buy it new. You think it wouldn't fall apart.

Fortunately, the glass/polarizer sandwich was okay, and the molten adhesive came off with water and dishwashing liquid. I epoxied it back into the filter ring, and it's been fine ever since.