How Have National Parks Changed Over Time?

Viewing photographs of different eras in the national parks can give many insights on ecosystem processes, as well as simply change over time. The photographs associated with panoramic lookout photographs provide a window on the past, and an opportunity to compare to the present with changes to land forms and land cover.

Infrared versus Panchromatic Film

Glacier National Park-Mount Reynolds-infrared film. Glacier National Park-Mount Reynolds-panchromatic film.

Compare the infrared with the panchromatic film. Mount Reynolds, Glacier National Park. Infrared (top) and panchromatic (bottom) images by Lester Moe, June 23, 1935.

Two types of Eastman Kodak film were used: 1. Panchromatic film, which is sensitive to light of all colors in the visible spectrum, and 2. Infrared film, which is sensitive to electromagnetic wavelengths longer than the visible spectrum, 0.7mm to ~3mm. Filters used with panchromatic film included a K2 (Wratten No. 8) and #12 deep amber (minus blue member of the cyan-magenta-yellow set of subtractive primaries); while filters used with infrared film included A-red (Wratten No. 25) and F-red (Wratten No. 29). The negatives and contact prints are of very high quality film and photography. However, the negatives, which measure approximately 5 ½ inchex x 13 ½ inches, are nitrate based and require careful handling and storage.

The crew used infrared film primarily in an effort to cut through any haze that was in the atmosphere. This produced a higher contrast image of the ‘background’ which was the primary focus of the images taken.

Compare the images above and below to see the differences between infrared and panchromatic film. In the black and white 1930’s images above, the differences are most visible in the vegetation and the sky. In the 2008 images below, the differences between infrared and panchromatic are very obvious, as healthy trees appear red in infrared images, and green in panchromatic images.

Glacier National Park - Looking Glass Overlook - infrared film. Glacier National Park - Looking Glass Overlook - panchromatic film.

Compare the infrared with the panchromatic film. Looking Glass, Glacier National Park. Infrared (top) and panchromatic (bottom) images by Ian Grob, August 22, 2008.

Material for this section credited to USGS Northern Rocky Mountain Science Center.