Products Category

Security Camera News

Home » Security Camera News » Little Knowledge For Infrared Photography
Little Knowledge For Infrared Photography
2008-08-19

What's so different about infrared? At the first glance, a monochrome picture taken in infrared may look similar to just another black and white photograph. And then you start seeing differences: objects which are bright in visible light (like sky) look dark here, while some of those which are "normally" dark (green foliage) acquire a bright glow. An unusual and eerie feeling. This can be explained with the graph at the right, showing the fraction of light reflected off various materials at various light colors (wavelengths). The height of the curves to the left of 600 nm shows how bright these materials are in visible light; to the right of 700 nm — how bright they are in infrared. The most dramatic difference between the visible and infrared spectrum is in case of foliage: it does, indeed, become very bright in infrared; very much like you can see in my photographs shown here.  To answer the question briefly: photographs in infrared show quite unusual tonality, different than that to which we are used, and this may make them esthetically pleasing, at least in many cases. Which, of course, is a matter of taste Film infrared photography Infrared film of many types has been available for decades and photographers have been using it successfully but not without some trial and error in their photography. If you ask any photographer who shoots or has shot infrared film he or she will tell you that it is a hassle and much more difficult to master or even get good results with over regular film photography. Here are a few reasons for this: Since infrared film is very sensitive to infrared light as well as visible it has to be handled, loaded and processed in complete darkness. Photographers have gone so far as to use blackout tape on the film window and around the film door on their camera to prevent light leaks fogging the infrared film. This was done even if the same camera didn't exhibit any light leakage with regular film photography. Because infrared film is sensitive to visible light as well as infrared light a special infrared filter needed to be attached to the front of the lens to block all visible light and only pass infrared light. Since all visible light is blocked by this filter we can’t see through it as it is opaque black to our eyes. As you may have already realized this makes it impossible to compose and focus as you no longer are able to see through the viewfinder. To overcome this problem the filter needed to be removed, the photographer, using a tripod composes and focuses, attaches the opaque infrared filter and takes some bracketed photographs. This process would need to be repeated over and over and over. Infrared light, being located to the right of visible red light, has a longer wavelength and thus focuses at a slightly different point. Because of this most lenses have a red infrared focus dot offset from the regular focus mark so that the photographer after focusing on visible light can move the focus ring to align with the red infrared focus dot. Infrared film only has a suggested ISO rating because the amount of infrared light varies from scene to scene independent from visible light. This would require the photographer to take a series of bracketed exposures in hopes that one would be correct. As you can see the steps required for film infrared photography are quite lengthy and complex compared to regular visible light photography and many have given up after some failed attempts. Digital Infrared Photography With the advent of digital cameras it is now possible to photograph infrared light with your digital camera and greatly simplify the infrared photography process. The latest digital cameras are sensitive to infrared light, so much so that manufacturers place a hot mirror filter in front of the sensor to block infrared light to prevent infrared IR light from spoiling regular photographs. It is still possible to shoot digital infrared photography with an unmodified digital camera but the exposures become quite long and in most cases require a tripod, not to mention the need to place an infrared filter in front of the lens to block visible light. All this sure doesn't help the creative infrared photography process. With digital infrared photography conversion it is now possible to photograph infrared images hand held at low ISO speeds and without the need for infrared filters. Since you no longer need to use an infrared filter in front of the lens it is much easier to change lenses, compose and focus. Thanks to the digital camera’s CCD chip, photography by infrared light has never been easier. Traditionally, working with infrared film has been difficult, at best. Infrared film requires loading the camera in total darkness, extensive exposure bracketing, special developing, and--at times--a bit of luck. With a digital camera, infrared filter, and a tripod, anyone can explore the near-infrared spectrum photographically with ease, repeatable results, and no guesswork.

[ Back ]
Copyright © 2008-2010 Security Camera B2B. All rights reserved.