What Is Infrared Photography? A Beginner’s Guide

Photography is kind of trippy. When we take a photo, we're essentially not capturing the world, but rather merely evidence that it exists.

When using a camera that closely mimics the way that we see, this self-evident truth is one that can be easy to forget. Infrared photography dispels us of this delusion by showing us things from a slightly different perspective.

What Is Infrared Light?

Visible light, as you probably already know, constitutes only a very small segment of the spectrum of electromagnetic radiation. At one end of this visible wedge is high-energy blue light. At the other end is red light, characterized by much longer and slower wavelengths of activity.

Infrared light is slower than even the slowest red light visible to us. This makes it totally imperceptible to us visually, but that doesn't make it any less important.

How Does Infrared Photography Work?

The way that conventional photography works resembles our own mechanism of sight greatly. How, then, can a normal camera “see” something that we can't?

At its heart, both human vision and camera vision are, indeed, very similar. Camera sensors are much more sensitive mechanically, however. They are able to “perceive” infrared light as an extension of the visible spectrum, albeit amongst the much stronger visible light that comes along with it.

In order to produce an image characterized by infrared light exclusively, all that a camera needs is a filter that blocks every other wavelength of light within the visible spectrum, as well as the ultraviolet light above.

What Is an Infrared Filter?

Optical filters come in many forms, some more practical than others. Many filtration manufacturers produce an IR blocker filter. These types of filters actually prevent infrared light from passing through to the sensor. Filters like this should not be confused with an IR filter, plain and simple, which actually does the opposite.

Like many types of camera filters, infrared camera filters selectively let light in by wavelength. Tiffen is the industry standard for infrared filters, but plenty of more reasonable options are also available.

What Is Infrared Photography Good For?

Distant objects in space emit or reflect light that reaches us over time. As light travels, it expends energy. The further the light is from the source, the slower each photon will be traveling along each ray.

If an object in deep space is far enough away from us, this effect essentially makes them “too dark” to see via ordinary means. The originally-visible light it delivers may already be moving too slowly to be seen by the time it hits us, falling below the bottom of the visible spectrum and spilling out into the near-infrared region.

Infrared space photography is able to pick up this type of light, making these celestial bodies much easier to study from home.

Infrared photography has a few practical applications here on Earth as well. Some types of legal currency, for example, have designs laced with “invisible” ink that reflects infrared light. Counterfeit bills can be distinguished from real ones through an infrared filter.

In the world of forensics, IR photography can be used to see things that the human eye may not notice right away. Bloodstains might be difficult to pick up when spattered on dark carpeting. Because blood absorbs more infrared light than carpet or fabric, infrared photos can help investigators see what's in front of them more clearly.

Related: What Does a Forensic Analyst Do?

How to Take Infrared Lens Photography

To start taking infrared photography, all you need to do is invest in an infrared camera filter. But how does an infrared filter affect the photo being taken? We're glad that you asked.

Infrared Color Spectrum

Infrared lens photography dramatically changes the color scheme of what we're used to seeing. The false color representation of the invisible infrared light will make it look like somebody has adjusted the “hue” setting on the entire world.

The sky will appear nightmarishly dark. Portraits of people take on an odd, alien-like quality. Freckles disappear, the extra melanin indiscernible from the rest of the skin.

The most noticeable difference between infrared pictures and normal photography, however, is the appearance of nature. The green color of plants and leaves will now appear to be titanium white. While not particularly useful when taking photos in color, this effect will often create a much more visually-exciting black and white photo when shooting out in nature.

Infrared Focusing

Another consideration is focus. Because of its longer wavelength, it converges to a point that will differ from that of the visible light emanating from the same source.

Related: What Is Depth of Field and How Does It Occur?

Any type of single-lens reflex camera relies on mirrors in order to function. Mirrors reflect infrared light in a thermal sense only. This unfortunate fact makes these systems borderline useless when shooting infrared light; SLRs and DSLRs depend on the intrinsic properties of visible light in order to predict where the incoming rays will meet one another.

Adjusting these tools so that they can be adapted for infrared photography basically means recalibrating them. Some lenses come printed with an infrared index mark, usually in the form of a red dot that's offset slightly from the mark that indicates correct focus ordinarily. Abiding by the correct mark for the type of photography that you're partaking in will yield the appropriate results.

In order to focus on an object 50 feet away when taking a normal photograph, you would roll the barrel until the 50-foot mark is in alignment with this default focus index indicator. When shooting infrared light, you would do the same, only using the red mark right next to it instead.

If you shoot with a mirrorless camera, you're in luck. With no mirrors separating the plane of photography from the subject, focus is determined directly at the sensor. No special measures will need to be taken to focus the image adequately.

Infrared Film Photography

Another option is to use infrared film, just like the photographers who existed long before us.

Infrared film photography is a process, one that takes place throughout the entire life of the photograph. It requires a specific type of infrared film stock that cannot be processed and developed in the same type of chemicals as ordinary film. Even though infrared film is sensitive to infrared light, an infrared filter will still be necessary for the most effective outcome possible.

In either case, for the most striking final result, you should be shooting subjects that are illuminated generously by a powerful source, such as the sun. Smaller sources of light can work, too, but usually only if you're shooting very close to them. Intensity is what you're after here. A weak or diffuse source trails off into even weaker infrared light, which will be more difficult to photograph.

Infrared Photos: Something Just a Little Bit Different

Infrared photography certainly has its own unique charm.

While not exactly the way to go if your aim is to paint a picture of the world as we know it, infrared pictures offer a glimpse into what feels like an alternate version of reality. To some, this may be a welcome and refreshing deviation from the ordinary.

Author: Emma Garofalo

Source: Emma Garofalo.” What Is Infrared Photography? A Beginner’s Guide”. Retrieved From https://www.makeuseof.com/infrared-photography-for-beginners-guide/

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