Polarisation Filter

[neildw]

Hi all,

I'm at the beginning of starting a new series which shall involve cars.
And I want to reduce the reflections as much as possible.

I'll be working with a 150 mm lens on a 4x5.

Any tips on what I should be looking at? What kind of pola filter?
Any tips on working with them on LF?

[BrianShaw]

Which 150mm lens? That would help of figure out which size polarizer filter to get. Only other suggestion would be also to use a lens hood.

[Drew Wiley]

Polarization is relative to the position of the light, where the sun is in the sky. And if you're using color film, too much polarization can make the colors look questionable. In a studio, you can predictably cross polarize floodlamps, along with a pola filter over the lens. But again, over-doing it will look paste-like and unrealistic. Most pola filters and polarized lighting "gels" have a slight greenish bias. Only the very best and most expensive doesn't.

[Alan Klein]

Don't assume you need to turn the polarizer to full impact, Because a car has a lot of bends and turns, the polarizing effect will shift and change the way it works on the various surfaces of the car as you turn it. So view it before you put it on the lens. Get the right position and note it. Then match that position when you mount it on the lens. Good luck.

[Pieter]

Polarization is relative to the position of the light, where the sun is in the sky. And if you're using color film, too much polarization can make the colors look questionable. In a studio, you can predictably cross polarize floodlamps, along with a pola filter over the lens. But again, over-doing it will look paste-like and unrealistic. Most pola filters and polarized lighting "gels" have a slight greenish bias. Only the very best and most expensive doesn't.

Also, most car shooters have a set of "shark fins"--large white foamcore cut in a wavy shape, sometimes like a shark fin, to reflect into the windows and polished surfaces, giving interesting reflections that are indistinct and not distracting. It may not be your style (very clean studio shots), but you might want to check the work of Michael Furman. http://www.michaelfurman.com

[r.e.]

Any tips on what I should be looking at? What kind of pola filter?

There are linear polarisers and circular polarisers. In this case, "circular" is a technical term and doesn't mean "round". There are square and round versions of both linear polarisers and circular polarisers.

Photographers stopped using linear polarisers with the advent of digital cameras. If you're interested, there's lots on the internet about the reasons. These days, a linear polariser should work just as well on a digital camera as a circular polariser, but the main filter makers don't make them anymore (apart from quite large, extremely expensive ones for high-end filmmaking) and nobody wants them. If you come across one, it is likely to be very cheap, and it will work just as well.

Recently we've seen the introduction of filters that combine a polariser with variable neutral density. There is quite a lot of information about these on the internet, as well as a fair number of YouTube videos about them. Personally, I'm not keen on variable ND and I have no experience with these new filters. That said, if you need neutral density, a variable ND filter is a lot cheaper than buying individual filters and can be a real timesaver, especially for video. These filters have become very popular for good reasons.

[Doremus Scudder]

Unless you have through-the-lens metering on your LF camera, you can use a linear polarizer. You can often find them used and cheaper than circular polarizers. Get a good-quality coated one for best results. B+W, Heliopan, and Hoya coated filters are all good. Get a filter for the largest lens you plan on using and step-up your others to fit; then you can use one filter for all of them.

Reducing all reflections isn't always the best solution, as mentioned above. If outdoors, overcast days are often your friend.

Best,

Doremus

[Bob Salomon]

Unless you have through-the-lens metering on your LF camera, you can use a linear polarizer. You can often find them used and cheaper than circular polarizers. Get a good-quality coated one for best results. B+W, Heliopan, and Hoya coated filters are all good. Get a filter for the largest lens you plan on using and step-up your others to fit; then you can use one filter for all of them.

Reducing all reflections isn't always the best solution, as mentioned above. If outdoors, overcast days are often your friend.

Best,

Doremus

Through the lens metering doesn’t necessarily mean you need a circular polarizer. Nikon, Canon, Minolta, Pentax, Rollei, Hasselblads all did TTL metering with no problem with a linear polarizer.
You need a circular pol if your camera uses a beam splitter for auto focus and/or metering.

[pdmoylan]

Several techniques I used to manage proper exposure:

1. I employed use of a 35mm film or digital camera as a meter, placing a Pola filter on that camera.
2. Since exposure loss with pola filters changes markedly to the extent you change amount of polarization, you will have to set the filter to where you see the changes you want in the scene and meter accordingly.
3. Place a comparable pola filter on the LF lens and adjust the amount of polarization to how you set it with the 35mm.
4. Experiment prior to calibrate exposure readings with the LF results. I had a 90mm f8 Nikkor which was always .5 stops darker than the exposure determined with the 35mm. My other lenses needed no adjustment.
5 so this process a. Eliminates having to exposure compensate for the pola filter but you will have to adjust exposure for any calibration differences.
6. Even with the best pola filters, I found color issues when using them in very low light, but this is particularly true with modern day digital cameras.
7. I found old tiffen linears to be somewhat neutral whereas Nikons tended towards blue (cooler) and calumet towards green.
8. Set your pola filter to neutral setting at first and watch change as you turn it. You may find that the slight polar effect at neutral position is sufficient. There is a marked difference between unfiltered clvs neutral position.
9. As Drew mentioned, using pola filters on artificial lighting in addition to on the lens may give you a denser look, something to experiment with.
10. I expect there are other methods of determining exposure compensation for pola filters, but they are not all the same regarding amount of light loss, particularly with the HR thin filters being made now.
11. The range of light loss I found to be between 2/3 and 1.5 stops depending on how much you turn that filter.

[Bob Salomon]

Several techniques I used to manage proper exposure:

1. I employed use of a 35mm film or digital camera as a meter, placing a Pola filter on that camera.
2. Since exposure loss with pola filters changes markedly to the extent you change amount of polarization, you will have to set the filter to where you see the changes you want in the scene and meter accordingly.
3. Place a comparable pola filter on the LF lens and adjust the amount of polarization to how you set it with the 35mm.
4. Experiment prior to calibrate exposure readings with the LF results. I had a 90mm f8 Nikkor which was always .5 stops darker than the exposure determined with the 35mm. My other lenses needed no adjustment.
5 so this process a. Eliminates having to exposure compensate for the pola filter but you will have to adjust exposure for any calibration differences.
6. Even with the best pola filters, I found color issues when using them in very low light, but this is particularly true with modern day digital cameras.
7. I found old tiffen linears to be somewhat neutral whereas Nikons tended towards blue (cooler) and calumet towards green.
8. Set your pola filter to neutral setting at first and watch change as you turn it. You may find that the slight polar effect at neutral position is sufficient. There is a marked difference between unfiltered clvs neutral position.
9. As Drew mentioned, using pola filters on artificial lighting in addition to on the lens may give you a denser look, something to experiment with.
10. I expect there are other methods of determining exposure compensation for pola filters, but they are not all the same regarding amount of light loss, particularly with the HR thin filters being made now.
11. The range of light loss I found to be between 2/3 and 1.5 stops depending on how much you turn that filter.

The density of a single polarizer, circular or linear, does not change as you rotate it. It always passes the same amount of light, regardless of its rotation.