Polarizing filter and Leica M8

[DBAUDUI1]

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Hello,

Can we put a polarising filter on our coded and non coded Leica Lenses while we use a M8? To me we can not use a polarisation filter together with a UV/IR filter, but do we nees the UV/IR filter when we use the polarisation one? P.S I am using Leica swing polarization filter (13132 for example) or the last one Leica produced, with the adapters for E46, E39...lenses Many thanks for your advise. Dominique.

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[UliWer]

UV/IR-Filters have an inner thread where you can screw in the mount for the polarizer. Though you should avoid to screw it in too tightly, otherwise you'll have problems to release the polarizer mount from the filter.

[ho_co]

You're right that you should theoretically always use the UV/IR-Cut filter on the M8, even with a polarizer.

 

I'm not sure the swing-out polarizer lets you do that, because IIRC it clamps to the outside of the lens, and the presence of another filter may block the polarizer's swing.

 

But for many shots, it would be worth trying without the UV/IR-Cut filter. After all, the IR sensitivity of the camera sometimes makes little noticeable difference, and with the polarizer you're trying for an effect anyway, rather than "actual" rendering.

 

Another possible solution would be to get a single large polarizer (say, 72 or 77 mm) and some adapter rings to mount it on the different UV/IR-Cut filters. (Keep in mind that a linear polarizer is all you need with the M's. A circular polarizer is fine if you've got one, but unnecessary on the M8 and M9.)

[Ronazle]

I glued a B&W 46mm polarizer into a Leica older 39mm swing mount and it works fine. After removing the original damaged polarizer, the 46 mm B&W fit very, very loosley in the existing threads, so I super glued it into the swing polarizer mount (it was seated flat). Be advised that the 39mm polarizer mount will not attach to the outer edge of a 39mm filter and is a problem with some lenses. However, it is possible to screw a 46mm cut filter into the front w/o any detectable edge fall off. Hope this helps , ron

[UliWer]

You're right that you should theoretically always use the UV/IR-Cut filter on the M8, even with a polarizer.

 

I'm not sure the swing-out polarizer lets you do that, because IIRC it clamps to the outside of the lens, and the presence of another filter may block the polarizer's swing.

 

 

The 13352 swing-out polarizer had a clamp to fix it on the lens. This does not work when you have a filter on the lens, for the clamp needs some bigger diameter than the filter.

 

The new universal polarizer for the M uses adapters for different lens sizes. Those adapters are screwed into the filter thread but may as bell be screwed into the inner thread of a filter.

[ho_co]

Thanks, Uli.

 

You're right that I was familiar with the 13352. I haven't played with the current one.

[jaapv]

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Unfortunately the relative amount of IR contamination gets more or less doubled by a polarizing filter, depending on the amount of filtering you choose, as most (there are some very expensive specialist ones) polarizing filters do not block IR light at all. So the IR filter is needed more than ever.

[Guest Linsengericht]

Unfortunately the relative amount of IR contamination gets more or less doubled by a polarizing filter

 

Sure? The IR part of the spectrum is polarized, just the like visible light. The ratio of IR and visible light should not change, unless the effect of the polarizer breaks down in the IR spectrum.

[Guest Linsengericht]

The ratio of IR and visible light should not change, unless the effect of the polarizer breaks down in the IR spectrum.

 

I just checked that with the Leica polarizing filter and a second linear (!) polarizing filter at 90° offset.

 

The basic setup is know from the "variable ND" filters. For 90° offset between two filters, we expect "total darkness". If the polarizing effect for the IR spectrum would be different from visible light, as jaap has suggested, we would block only visible light and see strom residual IR effects. However, in my test there was no indication of that. Visible light and IR light was both strongly attenuated.

 

We can conclude that the polarizing filter does not change the situation compared to images without the polarizer. The polarizer does not replace the UVIR filter, but on the other hand, it does not make the situation worse.

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[Ronazle]

I glued a B&W 46m....to screw a 46mm cut filter into the front w/o any detectable edge fall off. Hope this helps , ron

 

For clarity the last sentence should read: .... to screw a 46mm IR cut filter into the front of the "glued in B & H polarizer" w/o any detectable edge fall off.

 

I have seen no noticable differences using the polarizer/ir cut filter combination than I have seen w/film and the polarizer. Of course, two filters in tandem do not enhance image sharpness. regards, ron

[jaapv]

Sure? The IR part of the spectrum is polarized, just the like visible light. The ratio of IR and visible light should not change, unless the effect of the polarizer breaks down in the IR spectrum.

That is exactly what happens, The filter is not capable of separating polarized IR..

Those filters are available in specialist circles - if you are willing to pay, mainly for use in astronomy and laser applications:

 

http://www.codixx.de/polarizer.html

[Guest Linsengericht]

That is exactly what happens, The filter is not capable of separating polarized IR.

 

My experiment with the Leica polarizer has shown differently, as described above.

[jaapv]

The proper way to test this is to shine polarized IR light (preferably Laser to have an exact wave length) through a polfilter. It is quit possible the Leica filter blocks some near-IR, unspecified, as it was not designed to do so.

[DBAUDUI1]

Many thanks for all your comments.

I understand that for normal picture taking, when I want to use a polarization filter on an M8, I should use the universal Polarization filter from Leica and screw it into the UV/IR filter in use on the lens.

[Alx]

I've tried the leica pol filter on the IR-cut filter. Works fine, except the filter mount tends to jam onto the filter and you're stuck with either both on or both off!

[m0r0m0]

Polarizers for general photography are always of the film type. They consist of long dichroic molecules which are oriented and thereby made asymmetrically absorbing by stretching the film in which they are embedded. The amount of dichroism depends on the particular dicroic molecules in the film and is wavelength-dependent. JAAPV is correct to say that typical film polarizers are increasingly ineffective as the wavelength of the light gets into the IR. There exist film polarizers which do operate reasonably in the IR, but they typically absorb much more visible light and therefore would not be very suitable for use in general photography. There are other types of polarizers which work well over a very large range of the spectrum, from near-UV through near-IR, e.g. calcite crystal polarizers in one of several designs. Such polarizers are bulky, have limited aperture and are very expensive.

 

From the description of the test that was reported with an M8, it is unclear to me that that test would have detected the IR leakage that almost certainly exists for the Leica polarizing system. A definitive test would operate in the following way.

 

1. mount the two polarizers in series as was described

2. use daylight or tungsten light on the subject

3. set the two polarizers PARALLEL (0° relative orientation)

4. make a sequence of exposures until one sees a good IR exposure of the subject by looking at the histogram; record the value of the exposure (f-stop and shutter speed)

5. CROSS the polarizers (90° relative orientation)

6. make one exposure at the previously recorded value of the exposure

7. compare the histogram values, perhaps after importing both frames into LR and using the numerical values detected in the DEVELOPMENT mode

 

 

--- Mike

[Cyril Jayant]

I have noticed too on some of my testing photos done on M8 and B&W Liner polarizer filter mounted on to lens with UVIR filter. The fffect is almost invisible. When I turn the filtre to see the filter Polarize effect it dosen't change the light meatering at all. Does that mean There is no effct in metering?

[ho_co]

Polarizers for general photography are always of the film type....

 

Mike--

I've got some older polarizers (both Leica and B+W) that seem to have lost all or most of their ability to polarize.

 

Is this possible? Or am I crazy?

 

Thanks!

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[m0r0m0]

Cyril: the polarizer will absorb that part of any incident electric field (light) which is perpendicular to the "pass axis" (usually the one that's marked on the filter); the electric field of all the incident light from a scene will be distributed rather uniformly in all orientations; thus rotating the filter will cause the orientation of the absorbed light to change but will have only a very small effect on the amount of light that reaches the meter; so your observation makes sense; the amount of light that we typically want to absorb to enhance contrast and saturation actually makes up a rather small fraction of all the light from a typical scene, so this fraction will usually be too small to measure with a common light meter

 

Howard: the active ingredient of dichroic polarizing filters is like a dye; like other dyes it can be "bleached" to reduce the dichroism and thereby the polarizing capability of a filter; so yes, polarizers can lose their ability to extinguish polarized light; having said that, the dye is actually pretty darned stable; I've seen bleaching in polarizing filters, but only in UV laser damage tests of optical devices which employ polarizers (liquid crystal shutters); in that case the damage was a small "white" spot on the filter where the laser light was focused; the damage threshold, however, was much greater than the level that a photographic polarizing filter is likely to experience; however, the bleaching process should be cumulative, so a filter that was exposed for a long time in direct sunlight, for example, could eventually accumulate enough UV exposure to degrade its effectiveness; even a long enough exposure to fluorescent light could also do it; the situation very similar to the way color prints will "fade" with UV exposure

 

--- Mike

[ho_co]

Thanks, Mike, for the rundown on polarizing materials. You've convinced me that this isn't something I'm imagining.

 

I've got no idea what caused it, but both a Leitz swing-out polarizer and a B+W Käsemann have lost their oomph over the past 30 years. They were both stored in the dark at normal room temperatures. The Leitz unit has completely lost its ability to polarize but shows no obvious physical signs of deterioration. The B+W shows clear signs of separation between the glass and the polarizing material.