Infrared photography is done much like long exposure photography when used on a typical digital camera. The infrared filter (Hoya R72 in this case) blocks all visible light below the 720nm wavelength. As a result there are two hurdles to deal with; the extreme reduction in light most the camera receives, and the shift in focusing. A tripod is very helpful in dealing with the loss of light, the latter however requires some practice. My favorite lens to use for this type of photography is an old Pentax-M 50mm f/1.4 as it does not have the hot spot in the middle. Also, it has an infrared focusing mark on the lens allowing me to focus normally without the filter, and then turn the focus ring to match up with the infrared mark.
I enjoy this type of photography because with an unmodified camera, I have to consider the effect of long exposure as well as consider the way infrared light works; which behaves differently than visual light especially depending on the scene. Many newer digital cameras are ill equipped to be used with an R72 filter as the manufacture are continually improving the sensor quality to block light that causes undesirable effect such as purple fringing and chromatic aberrations.