Anatomy of an Infrared Conversion

Today’s Post by Joe Farace

“The object of photography is to express what is in your heart and mind.”— Yoshihisa Maitani

A typical digital camera’s sensor sees a range of light in wavelengths from approximately 350 to 1,000 nanometers. A nanometer (nm) is a metric unit of length equal to one billionth of a meter. Your eyes usually see a range of light from approximately 400 to 700 nanometers. Most digital cameras place a low pass filter directly in front of the imaging sensor to allow low frequency light visible to the human eye pass through to the sensor where it’s captured and recorded but blocks unwanted light from the infrared and ultraviolet spectrums (the high end and the low end wavelengths) from polluting a photograph’s color. As owners of early Leica M8 cameras quickly discovered that this piece of glass is important for maintaining maximum color fidelity.

During modification for IR capture the low pass filter that prevents infrared and ultraviolet light from striking the E-P1’s sensor is removed allowing all—visible and invisible—light to pass through. In this procedure, the camera’s low pass filter is not replaced with a piece of optical glass because Olympus packages and seals its Dust Reduction and Image Stabilization Units along with the sensor into a single assembly with the lens-facing part of the assembly covered by a piece of optical glass that’s sealed with an O-ring. During the IR modification this unit is disassembled, the low pass filter is removed, and all parts are re-assembled with the lens-facing optical glass and seal remaining in place. This is important because it allows the E-P1’s dust reduction system to remain intact and functional. After all this, what ultimately gets captured depends on what kind of filter you place in front of the lens.

The above quote is from the designer of the original half-frame Olympus Pen camera and was quoted in my “On Test” of the Olympus E-P1 for the January 2010 issue of Shutterbug magazine. This image was made with an E-P1 with Olympus 9-18mm f/4-5.6 lens and an exposure of 1/500 sec at f/11 and ISO 400. The image file was tweaked and toned using Google’s Silver Efex Pro.

Tip: Try infrared by having an old camera, like an E-P1, that’s gathering dust converted to IR-only operation. You can save a few dollars when converting your camera to infrared at LifePixel by using the coupon code “farace.”