Boat House Tower, North Park IR

North Park IR

A long stretch of cold, cloudy late-winter weather is making for some somber photography sessions. I took my IR-modified camera out to North Park (in a suburb of Pittsburgh) today to see if I could generate anything interesting. I focused mostly on some of the more interesting buildings. Because the grayness of the day and the landscape, and the subject matter, I converted things to black and white in most cases.

Smith Grave North Park IR

Smith Grave North Park IR

All images were taken with a Fuji IS Pro UVIR modified camera. The lens was the Nikon 18-55mm AF-S DX VR, with a 720nm IR-pass filter. The biggest challenge with this rig is focusing. Manual focus with the IR filter in place is impossible. Auto-focus with the IR filter in place works sometimes, but is not reliable, especially in poor light or with distant subjects inside the infinity setting. My principal technique today was to use a flip-down attachment for the filter (actually a Nikon AF-1 gel holder, fitted with step rings to accept a screw-in filter). I would drop the filter, manually focus or autofocus, then flip the filter back up. On this 18-55mm lens, the manual focus gearing is very loose and coarse; small movements tend to change the focus significantly. It was difficult to flip the filter back into place without disturbing the focus. One trick for better control was to use the auto/manual focus switch on the camera as a kind of lock for the focus. However, I had to turn the autofocus back off before pressing the shutter to take the image, because the camera would want to auto-focus again–with poor results due to the interference of the IR filter. To compound the issue, the Fuji IS Pro LCD display is small and will not zoom very far into a captured image, so it’s difficult to know how sharp a final image may be while in the field. The “lone tree” shot was one that just would not cooperate; I have deliberately kept the image size small to maintain the illusion of sharpness. Using a tripod helps keep hands free for careful use of the filter without messing up focus–or composition (another hazard of a flip-up filter), though about half of today’s images are handheld.


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