Experimenting with Infrared

This image was made on a sunny day in downtown Ada with a 28mm lens on my Kodak DCS-720x modified for infrared use. The filter was deep red.
This image was made on a sunny day in downtown Ada with a 28mm lens on my Kodak DCS-720x modified for infrared use. The filter was deep red.

In early 2003, I saw that Kodak was liquidating their remaining stock of one of their last digital SLR cameras, the 720x. The camera had been developed in the late 1990s to succeed a long line of digitals that were intended for the news gathering and photojournalism sector, and while they were fairly well suited to the tasks for which they were designed, Kodak was, at that point, being mis-managed into a second-tier player in the camera field. The result was that photographers could snatch up their cameras at fractions of the original retail price for some very nice hardware, and I was one of those photographers.

Here are four test frames made with the Kodak DCS-720x and four different filters, the deep red (25a), the deep green (X1), a medium yellow (Y48), and a 720nm infrared filter, showing the unedited visible results.
Here are four test frames made with the Kodak DCS-720x and four different filters, the deep red (25a), the deep green (X1), a medium yellow (Y48), and a 720nm infrared filter, showing the unedited visible results.

As I have discussed previously, the 720x was designed with the option to use an anti-aliasing filter, and did not ship with one installed, allowing the camera to take advantage of the enhanced sharpness without the filter, with the trade off of sometimes difficult-to-remove aliasing. To do this, they installed a removable infrared filter in front of the SLR mirror assembly, which could be replaced by an anti-aliasing filter by customers who wanted it.

By 2009, my 720x had been largely usurped in the field by lighter, faster cameras, most notably by the outstanding Nikon D2H. The 720x was not only slower, it was substantially heavier, and used older-generation NiMH batteries, which became expensive and hard to find, and performed poorly next to the amazing lithium batteries of the new cameras. All this led me to remove the camera from service. As it sat in my office doing nothing, I thought to myself that I might remove the infrared filter and play around with the sensor’s behavior with infrared light. After all, there are some companies that will modify existing SLRs like the Nikon D70 to be sensitive to infrared by “surgically” removing the infrared filter, which on all but the Kodak are cemented to the face of the imaging sensor.

I already had a deep red filter, which we all have sitting around from our black-and-white film days, and I also purchased a set of true infrared filters, the kind which don’t pass any visible light.

I’ve been playing around with the combinations of the 720x and the filters off and on as time has permitted. I have been most happy with the results from the deep red filter, but even then the images out of the camera require a lot of editing and some imaginative color manipulation to achieve anything close to what I feel is successful infrared photography. With the red filter, the colors are initially all bright red and orange, but the Kodak makes raw files, with which I can use a combination of eyedropper click balancing and Kodak’s “Look” option to create color that approaches the infrared rendering I like. The real beauty of the infrared rendering is that the relationship between the colors breaks down, with reds and blues trading places, dark areas appearing light, and on and on. The true infrared filters, oddly, are not as interesting, since all the color information is translated into the same monochrome rendering. It has, however, shown me a few things about light, such as the fact that the red paint of a stop sign and the word “stop” reflect the same amount of infrared energy, causing the sign to appear blank.

I’ll continue to experiment, particularly with the true infrared filters. Since they don’t pass visible light, you can’t see an image in the viewfinder with them mounted, resulting in needing to either remove them to compose and focus (remembering to compensate for the fact that infrared light is longer in wavelength than visible light), or to take another camera along with the same focal length mounted to use as a de facto viewfinder. Regardless, the filters pass so little light that it is always necessary to use a tripod. Even at ISO 400 in bright daylight, exposures at f/8 can be two full second or more.

It’s interesting. I’ll keep playing.

This is the seemingly very naked imaging sensor in my 720x. Photographing it was a pain because it was hard to get any light to actually shine on it deep inside the camera. I ended up using an LED flashlight.
This is the seemingly very naked imaging sensor in my 720x. Photographing it was a pain because it was hard to get any light to actually shine on it deep inside the camera. I ended up using an LED flashlight.
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