Origin: Latin - "Below Red"
Starting at the limits of our vision at around 700nm, infrared (IR), is the spectrum of wavelengths longer than those of visible light. Whilst infrared extends for thousands of nanometers, the limit of what is commonly known as IR is around 1000nm.
For this reason, this band is sometimes called Near Infrared (NIR) to distinguish itself from other bands in the spectrum such as long-wave infrared (LWIR) – better known as thermal.
Night Vision | Landscape | Reconnaissance
The most obvious and widespread use for infrared is to see in the dark, but there’s much more that IR can be utilised for.
Landscape photography is a popular choice for IR as colours can be manipulated for creative effect: white trees, red grass and pink skies are just some of the possibilities. Because IR isn’t part of the visible spectrum, any colour combinations are completely valid.
Historically, infrared photography was even used for reconnaissance and as a counter-camouflage measure. By turning foliage red, people and vehicles would stand out from their surroundings of jungle or forest.
Active Illumination | Passive Illumination
All IR imaging requires some form of illumination. During the day this is not a problem: the sun outputs more IR than visible light.
During the night or in any darkened room however, artificial sources will be necessary. Just as we can’t see if there’s no visible light, an IR camera can’t see anything if there’s no infrared light. IR sensitive cameras such as CCTV systems typically utilise infrared LEDs to light up an otherwise dark area at night – this is called active illumination.
Military-grade night vision goggles on the other hand are a form of passive illumination, using technology called image intensifiers to amplify available light – whether visible or infrared – without needing additional illumination.
When filming in infrared, you will require a camera which is capable of “seeing” the infrared spectrum. A full spectrum camera is sensitive to ultraviolet, visible and infrared light and so is perfect for the job.
For night vision applications, filtration is usually not necessary as there’s often no visible light to block out.
If a pure infrared image is desired, IR bandpass filters can be used to block out the visible spectrum.
Specialist creative filters like the Aerochrome filter pass selective wavelengths from both the visible and IR spectrums to produce unique colour combinations in-camera that are hard or impossible to replicate any other way.
Most standard photography or cinema lenses will work in infrared.
That said, some lenses exhibit hotspots in the centre of the image, generally becoming more evident at deeper (smaller) apertures. The only way to know for sure is to test them prior to filming in infrared.
Also worth bearing in mind is that IR light focuses at a different point to visible light. Autofocus lenses may not be reliable and witness marks might be off.
Unless using the Aerochrome filter, which produces rich, hue-shifted colours in-camera, expect to post-process your files more than you typically would for regular photos or video. The contrast will be milky and you may need to mix or swap the RGB channels in order to produce the desired colours. During shooting too, play around with the white balance and tint to find a suitable starting point – this will likely be at the extreme cool end to balance the excessive red tint.
Is it safe?
Yes, in most scenarios, infrared is safe to look at. However, the energy given off in the infrared spectrum is not just in the form of light, but heat as well.
Whilst our iris contracts to limit visible light, our eyes have no way of regulating infrared energy. Therefore you should not look directly into powerful IR sources in close proximity, as the heat can damage your eyes.
Typical infrared sources do not pose this hazard and the above warning is given as a precaution only.
Get in touch
If you have any further questions about filming in infrared or would like to hire our IR camera equipment, don’t hesitate to give us a ring or drop us an email.