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08/21/2004 12:41:28 PM · #1 |
I recently acquired a hot mirror filter at a bargain price just to see if my camera would benefit from this filter.
The results are very positive. Though the camera has a builtin hot mirror on the CCD sensor, I noticed an immediately improvemnt in image quality with the external filter.
First, the autofocus function of the Nikon N90 body was much crisper (more accurate) and the program exposure is also much better, having less tendency to underexpose images.
But the most dramatic improvement is in the lower noise levels, especially in shadowed areas of an image.
The camera is a Kodak/Nikon DCS 460 manufactured in 1995 so I was unsure of the technical state of the art when it was produced.
Has anyone else had similar experience with an external hot mirror filter? |
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08/21/2004 12:45:38 PM · #2 |
I have no idea what a hot mirror filter is, but I'd love to find out. How about posting some examples from your recent experiments?
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08/21/2004 12:52:18 PM · #3 |
A Hot Mirror is a mirror that reflects only infra red (long wavelengths) but passes visible light with very little attenuation.
Most digital cameras have this mirror builtin to the CCD sensor though some have one integral to the lense assembly. Accurate exposure and color is very difficult to achieve without his filter because of the sensitivity of the CCD (or cmos) sensor to the IR wavelengths.
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08/21/2004 01:00:33 PM · #4 |
do yuo have link to this filter or some sample images???
James
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08/21/2004 01:04:12 PM · #5 |
Come comparisons between filtered and not filtered pics would be great mate. I have never heard of these before and I am interested to see the results.
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08/21/2004 01:32:35 PM · #6 |
| I will produce some images and post them soon. |
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08/21/2004 01:52:33 PM · #7 |
Here are two images photographed under identical conditions except that the first has no external hot mirror.
Differences are subtle but the image with the hot mirror exhibits better saturated green while the sky and clouds seem a bit washed out.
Focus is slightly more crisp with the mirror and contrast as well. In this image noise is not noticeably different.
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08/21/2004 02:09:42 PM · #8 |
Looking side by side it was hard to see the differences. So I downloaded both images into ACDSee so that I could "flip back and forth" between the two. That made the differences much more obvious.
I think the main thing is that the first image shows a bit of haze across the image (especially noticeable in areas that should be green). With the hot mirror, there is very little haze and so the contrast is much better in those areas. It also ends up being sharper because of it.
Very interesting, thanks for sharing!
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08/21/2004 02:20:12 PM · #9 |
I agree with david. The the colour is much better greens and the blue car is much better too. The overall sharpness it great too. The haze can be taken care of with a haze/uv filter but the hot mirror helps the blues and greens in this sample. Thanks for sharing... Food for thought.
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