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Polarizing filters for EX-1
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I’ll defer to you guys on the color shift thing, since I’m no expert. In my photography experience as a hobbyist, I notice a difference that I have attributed to a lot of reflected blue light (from snow, etc) that gets filtered out. I wouldn’t say that there is a color shift inherent to the filter. Any correction would be appreciated 🙂
Cf
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A polarizer, when properly utilized, shouldn’t shift colors, it removes glare.
To oversimplify this somewhat…coins can only go through a coin slot in one angle…it’s a slot. Coins pushed at the slot that are rotated so they won’t go through can’t pass. Light waves tend to modulate at all sorts of angles…a polarizer is like introducing a coin slot.
The effect is usually most pronounced with shiny, reflective surfaces at, or around a 30 degree angle to the camera…rotating the polarizer will take a massive specular glare off a new car, or allow you to see through the store window by removing the reflection of the street behind you.
The color shifts can happen when you use a linear polarizer on a 3 chip camera. There is a system of reflective/transparent surfaces that separate the light into the proper wavelengths to pass to the proper sensor. These surfaces are themselves a sort of polarizer.
When you take two sets of polarized sunglasses (or two polarizer filters for that matter) and look through both of them while turning them in opposite directions, you’ll see that when they are at a 90 degree angle to each other, they’re opaque. They block all light.
When a linear polarizer does it’s thing and passes the polarized light to the prism in the camera, the angle of the polarizer combining with the angles of one or more of the camera’s internal mirror surfaces will act like a multiple polarizer, and since the surfaces that allow or reflect light to each sensor are at different angles, the angle of the polarizer will interact with different wavelengths, therefore different sensors, therefore different colors…creating color shifts as the wavelengths of light will vary in strength from one sensor to another.
A circular polarizer is not named for its roundness. A circular polarizer takes the polarized light and sends it to the camera “twisting” like a corkscrew. Even though the light is still polarized, since it’s angle is now rotating onto the sensor/prism assembly, no imbalance in color strength is created.
As far as Infra Red…that’s a Ex1/Ex3 thing that has little to do with polarization. The camera is simply sensitive to IR and does create some reddish hues in the blacks. Tiffen has an IR filter developed specifically for the purpose of neutralizing this issue.
TimK,
Director, Consultant
Kolb Productions, -
[Tim Kolb] “Tiffen has an IR filter developed specifically for the purpose of neutralizing this issue. “
…and it’s called the Tiffen T1 IR filter. It’s worth about $140.00 ea. CAD and it’s a “must have” for anyone using an EX1, EX1R or EX3.
You can read a great (but short) article about the issue here:
– Don
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Tim and Don, thanks for these very detailed and useful posts. Do you recommend stacking the T1 and polarizing filters? I realize that they won’t fit under the lens shade.
Jay Curlee
JC Communications
Makers of Rocking the Boat: A Musical Conversation and Journey
http://www.rockingtheboatmovie.com -
No one ever wants to stack filters, and the Tiffen T1 is really only used with tungsten lighting, while a pola is best used for a front lit sky. I don’t think anyone would stack these filters.
Stacking filters can cause strange flares, reflecting from the back filter to the front filter, generally not a good idea.
Good Luck
Michael Palmer -
.”and it’s called the Tiffen T1 IR filter. It’s worth about $140.00 ea. CAD and it’s a “must have” for anyone using an EX1, EX1R or EX3.”
I was under the impression that the far red problem had been corrected on the EX1. Anyone run into it yet with the new camera?
Thanks
mb
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Mark,
The blog at AbleCine has a pretty good article showing the differences when using the Tiffen T1 IR on the EX1. The far red issue is a lot better on the newest version of the EX but it’s not perfect. The PMW-350 looks pretty good though. You can see the article here:
https://blog.abelcine.com/2009/10/29/tiffen-t1-ir-filter-and-the-ex-cameras/
– Don
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