If you have ever thought of trying out infrared (IR) photography, you might know that this technique is far from being a new one as publications date back to the early 1900s. During the WWI, IR photography had been a valuable tool as the images were not altered by atmospheric haze contrary to normal photos. IR photos also helped to differentiate buildings from vegetations and to locate any munition supplies. Rivers and other water points were also shown in a more obvious color, making them more noticeable.
This particular method comprises of capturing invisible lights. Infrared lights are indeed invisible to the naked eye as they are generally located between 750-900 nm while the human eye is able to catch electromagnetic spectrum that lie between 400 and 700 nm. The images captured are then post-produced using a software such as Photoshop for example.
If you have not yet come across these kind of images, it might be because they are now relatively rare as most digital cameras now come equipped with filters specially designed to block out infrared lights. These kinds of photos also require long exposure which might cause digital noise or leave the image being blurry.
If you have the right equipment and knowledge on the technique, you might get involved in an infrared photography project. You might use a 35mm IR film with your SLR camera. You might also use an IR filter to block out normal light. This technique yields original shots that have a dreamy and almost nostalgic feel to them.