Tripod Techniques: The Unseen World

Do you know you can use your DSLR to capture a spectrum of light that cannot be seen by the naked human eye?

All DSLRs have an IR-blocking filter installed between the lens and the sensor. Despite this, most of them react to some near-IR energy, but at levels far lower than visible light. To make infrared photos, you need to filter out the visible light and only allow the near-IR and IR spectrum through.

This image was made using a camera converted for the full spectrum. The slow shutterspeed is only due to gloomy weather. Exposure: 1/10sec at f/14 (ISO 800) Photograph/Manish Mamtani

Using Filters
IR filters are actually visible-light blocking filters, and so, are quite dense and nearly Switch to the B&W mode of your camera or simply shoot RAW and process the stunning false colour images later. opaque. Since they block most or all of visible light, you will need very long exposures, and hence, a tripod.

Puzzling Out the Exposure
Focusing and exposing accurately become difficult when the filter is on. You need to set the exposure, achieve focus and switch to manual focus before you screw on the filter. This is also why you need to set your camera on a tripod so that the frame remains constant.

Quick Tip
If you have a secondary body, you can convert it to a full spectrum camera. Companies such as LifePixel can replace the filter inside the camera to allow only IR to pass through.

For more cool tips on tripods, click here.

This article originally appeared in the March 2014 issue of Better Photography.