Because of the nearly white reproduction of most vegetation’s chlorophyll, infrared black-and-white photographs render landscapes as if they were glowing, moonlit, or immersed in an extraterrestrial light.
Because exposure meters either hand held or in-camera are not sensitive to infrared light, it’s difficult to calculate exact exposures but that doesn’t mean you can try, especially with IR-converted digital cameras that provide instant feedback.
Two subjects that appear equally bright in visible light might reflect infrared radiation at significantly different rates and have different brightness when captured with an IR-converted camera or by using infrared filters. My Panasonic Lumix G5 converted for IR-only capture was used to make the above photograph and it tends to slightly underexpose even though the image on the LCD looks perfect. And histograms aren’t always a good indication either.
When getting started in digital IR photography it’s a good idea to bracket a series of three to five different exposures because you can’t count on your LCD screen giving you the kind of result you’ll see when viewing the files on a calibrated monitor. Most cameras offer a built-in bracketing function but even if your camera doesn’t have a bracket function it should have an Exposure Compensation feature that will let you adjust exposures on one-half or one-third stops while in the various automatic exposure modes.
If all fails, most cameras offer a manual mode and you don’t need a hand held exposure meter to get started in manual mode. Typically I look through the lens and see what the suggested exposure is in Program mode, then transfer that shutter speed and aperture to the camera after it’s set in manual mode. You are now free to change shutter speed or aperture to bracket exposures just like in the good ol’ days.
My book, The Complete Guide to Digital Infrared Photography is currently out-of-print but copies are available from Amazon for around $14. Creative Digital Monochrome Effects has a chapter on IR photography and is available from Amazon with new copies under $6 and used copies less than three bucks, which is a heckuva deal.