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| A: Maximal polarization | B: Intermediate polarization | C: No polarizers | ||
| "False-Colour Infrared" | "False-Colour Infrared" | "Visible Light" | ||
( images taken in May, 2000 using 35 mm f/2.8 PC-Nikkor lens on a D1, with stacked polarizers - © Bjørn Rørslett/NN )
Sometimes you are in for really bigsurprises. I've experimented with stacking polarizers severaltimes before, and obtained some strange effects with film-basedsystems. However, when I tried this trick with my D1, Iunexpectedly got images that closely resemble those offalse-colour infrared film. The pale spring sky turned into adeep blue, and the fresh foliage became vibrantly red. Since Iobtained the first shots, shown above, I have verified that thisis indeed an infrared image. If I add a Tiffen hot-mirror filter(which blocks IR) to the stack of polarizers, the colourrendition of the digital image turns into the ordinary again.However, besides involving IR, the "false-colour"images have an additional UV component. This is readily apparentwhen using the UV-Nikkor 105 mm f/4.5 to record"false-colour" images: I tested this using dandelions,which have a distinct UV patterns in their flowers, and sureenough, this familiar pattern emerged. When the usualMicro-Nikkor 105 mm f/4 was substituted for the UV-Nikkor, the UVfloral pattern disappeared. I'm going to publish such pictureswhen I'm entirely familiar with this novel technique.
I knew in advance that Nikon D1 could capture UV as well as IR radiation, and already had the images to prove this. However, why I got the stunning "false-colour" IR effect is quite unclear to me. That doesn't matter much because it's obvious that interesting pictures can be obtained. So be it.
Then, how is this effect obtained, besides just using a D1. Really it is simplicity itself. You just need to stack two polarizers atop each other. At least one of these should be the linear type, preferably both. Also, experiments show that combining high- and low-quality filters give the best results. For my usual setup, I attach a B+W 60 mm thread filter onto an old Nikon 52 mm polarizer (this filter has outer thread size of 60 mm so mates happily with the B+W). In the beginning, with F5 and Arca-Swiss cameras, I used a Hakuba filter instead of the Nikon to get even more stunning results. Unfortunately, for some non-explicable reason I gave my poorly-performing Hakuba filter away before it could be tried in the digital era. When the filters are rotated independently, you'll notice strong attenuation of light and sectors of irregular colours will appear. Adjust the polarizers for a maximum effect and take the picture. Be aware that using a linear polarizer will throw off the meter on D1, so some experimentation is called for. Because exposures can be checked using the LCD display on D1, this is in fact quite easy. Make sure you also try different degrees of polarization, as this will impact the colour rendition by a significant degree.
Please note that due to the thickness of the filter stack, focal lengths shorter than 35 mm will show vignetting of the image even on the D1.
For more information on the Nikon D1 camera and its performance under field condtions, my review pages for it should be consulted.