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UV IR filter on Film


Elliott J

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Hi. I have recently started shooting film again. When switching lenses between my M8 and M6, do I have to concern myself about removing the UV IR filter? If I do not remove it, what is the effect on my film? If anyone has any experience with this could they please share their thoughts?

Thanks.

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Hi. Thanks. I guess I will have to do a test. Didn't realize that would have that effect??? Thought the "color shift" was not as a result of the IR on an M8, but rather because of the proximity of the rear element of the lens relative to the sensor? The filter, I thought was being used to correct for problematic color shift in blacks under mixed light sources. If anyone can help clarify it would be greatly appreciated. ej

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It has to do with the angle of light that comes through the front of the filter. These filters are interference filters and work by having a carefully prepped number of coatings that are precisely placed fractions of a wavelength apart from each other (on the order of a couple hundred nanometers). Or something like that :) Regardless, as the angle of incidence changes from the front of the filter, the wavelengths they filter changes. That's the problem with wide angle lenses; the light is hitting the front of the filter at an angle other than perpendicular, changing the wavelength that is filtered.

 

So, the M8 needs the filters because the chip has a weak IR filter on it, and thus needs a filter on the front of the lens to filter out IR (which causes the magenta color of some black materials), but the cyan corners thing is a purely optical effect, and will affect any capture medium. Actually, if you hold the filter up to your eye and change the angle, I'm sure the color changes. It probably looks reasonably clear perpendicular and reddish at larger angles.

 

Wiki - interference filters

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