D70s modified for IR + visible + UV photography  

When first introduced, the D70s was an interesting camera. It had several improvements over the older D70 model, and a lower price tag. It still is a quite capable camera, in some respects better than the D50 and D40. It was my first DSLR, and served me well for a couple of years, before I switched to a D200. Since that time, I had no use for the D70s, except when I needed pictures of the D200. After leaving the D70s in a box for over six months, I thought of a use for it.

With the D70s, I was barely able to record any UV by using long exposure times, and with the D200 practically nothing useful. Fortunately, Life Pixel Infrared offers a solution. They begun their business by converting digital cameras for infrared photography, by placing an IR-pass filter in place of the anti-alias and IR-block one mounted on the sensor. They subsequently begun offering other services, like fully transparent windows for UV + visible + IR photography and replacements for scratched anti-aliasing filters. They also sell the filters alone if you are willing to do the job yourself, which was my choice. The conversion service they offer is expensive, but it is performed in a clean-room environment and includes focus adjustments. Some minute dust particles, however, are bound to end up between filter and sensor even in their controlled environment. This is the reason why camera manufacturers always replace the sensor and filter assembly as a whole. Once a camera leaves the production plant, there simply is no way to prevent dust contamination if the filter is removed.

A home-made conversion with a filter supplied by Life Pixel is feasible if you are technically inclined and have some experience assembling and disassembling camera equipment, but there is much that can go wrong. In my case, instead of following the procedure for opening the D70s recommended by Life Pixel, I followed a simplified procedure found on another web site. I did succeed in changing the filter, but one of the cables joining the PC boards at the back and bottom of the body loosened, and in practice I had to further disassemble the camera to put it back. Reconnecting these cables can be difficult, and I had to try twice before getting it right. I do recommend that you place the battery back and test whether the camera turns on, the LCD screen at the back works, and the camera can shoot pictures, before you reassemble the camera completely. A blank white or dead LCD screen is a sure sign that one of the cables is not plugged correctly into its connector.

The converted D70s still can be used for normal (i.e., visible-only) photography, if you mount an IR cut filter (usually of the hot-mirror type) in front of the lens. Without the filter, virtually all subjects produce deep-magenta pictures (above), because the CCD sensor is far more sensitive to IR than to visible light. A UV-cut filter is not normally necessary for visible-only photography, because most lenses cut these wavelengths, and the sensor is not very sensitive to UV to start with. At least in principle, removing the anti-aliasing filter makes the camera more sensitive to moiree artifacts, but also slightly improves its resolution.

Multispectral converted D70s, no filter.

Above is an example straight from the camera. The main differences between an unmodified camera with IR-pass filter in front of the lens and a modified UV+VIS+IR is that the latter lets you shoot IR pictures hand-held with normal illumination, and that visible is combined with IR (which is recorded mostly in the red channel). Ripples and waves on water stay sharp, instead of turning into foggy mush, and moving people and cars do not "magically" disappear from your IR shots. Also, colours do not completely disappear. Some of the laundry in the above picture has distinct colour differences, which could be enhanced by post-processing. The colour of the purple shirt at the left probably is caused by UV-induced fluorescence, in addition to visible light. The first three test pictures on this page were taken with the Micro Nikkor 60mm, so they contain virtually no UV.

Yellow flowers usually stay yellow even with the modified D70s, while leaves typically turns magenta. The above picture had the blue and red channels swapped and re-equalized in post-processing, to return the leaves to an approximate green. Many small animals, like the spider on the flower (above), turn semi-transparent in IR.

On the other hand, red flowers and fruit often turn white or, like the red rose of the picture above, light shades of mauve or blue.

With a lens that transmits fair amounts of UV and a UV-pass filter, you may even be able to shoot hand-held (above, taken near sunset), if you are willing to push the sensitivity all the way up. UV is recorded in the blue channel, while indigo (passed by the Schuler filter) is recorded both in the blue and red channels. The indigo "aura" around the tree tops is caused by leaves back-lit by the sun.

With a true UV lens (UV Rodagon 60mm), it becomes possible to explore the realm of near-UV, near-IR, or the full spectrum between near-UV and near-IR.

This example is a flower in UV fluorescent illumination, with UV Schuler filter. The common UV pattern used by insects to locate flowers (darker areas of petals near centre of flower) is well visible. The UV-bright petals stand in contrast to the rest of the plant, including several still-closed flower buds.

The same subject and illumination, without filter. Some visible (especially indigo and blue) and IR is present, in addition to UV. The UV pattern is still visible, but contrast is lower.

The same subject, with incandescent illumination and custom white balance set on the subject. This is combined visible and IR illumination, practically without UV. The blue veins on the flower buds were previously invisible under UV illumination, but the UV pattern of the flower has completely disappeared. The flower buds (yellow in reality, like the flowers) are fairly similar in colour to the open flowers, but this is not how insects (with eyes sensitive to UV) would perceive them.


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