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Bard Hill |
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Photography by Peter Boorman |
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All images on this web-site are Copyright Peter Boorman, 2003 unless labeled otherwise |
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I put this page up in connection with a thread on the RPE35 Usenet group. It is a set of transmission graphs for Pentax filters - Pentax because that is the one I could find easily, but I expect it won’t be very different for other quality manufacturers. What I find interesting is that for the coloured filters for B&W there is a very sharp cut-off, as one would hope and expect, and that that is very much mirrored for the UV filter. I wouldn’t expect glass that wasn’t specifically UV inhibited to produce such a sharp cut-off as this, and so wouldn’t expect lenses by themselves to limit UV transmission nearly as much as the filter - though wide range zooms with lots of elements will obviously absorb more. Different sort of glass, but we all know that it is still possible to get sunburn through a car window... |
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The lines for Skylight and Cloudy filters are interesting too. “Cloudy” is what Pentax calls a filter that is more or less an 81A - a mild warm-up filter to counter excess blue in shade and that is about twice as warm as a Skylight. It is interesting that these are both very different from the UV, behaving more like colour correction filters than the B&W series of ‘minus colour’ filters. |