I was recently inspired by my friend John, to have a go at some infrared photography, so I have been experimenting. Until now I had thought you could only do this with a specially adapted camera which can be expensive. Then my infrared eyes were opened when I discovered that a relatively cheap filter could be placed over an existing lens which cuts out all visible light, just allowing the infrared wavelengths through to the sensor in the camera.
These are my first attempts at nearby Slapton Ley. This is the World War 2 tank memorial to Operation Tiger. It was my most successful attempt.
It is a tricky procedure because as we can't see infrared and all visible light is excluded, it means that through the camera all is dark and the autofocus has nothing to focus on. This means you have to set up the camera and the focus, then switch off the autofocus and then fix the filter on to the lens, without moving any part of it. This is trickier than it sounds and it can result in blurry photos. Once the filter is on it is all guesswork. Due to the restriction on the amount of light available the shutter has to stay open much longer than normal and must be held motionless on a tripod. I was using 15 seconds to 30 seconds by way of experiment. That is longer than you realise.
All instances of infrared vision that researchers have definitively discovered are exhibited by cold-blooded species like snakes, amphibians, and insects. In other words, the most alien of our natural predators tend to exhibit vision that falls on the infrared spectrum. But there are some signs that more common mammals might be able to detect the infrared spectrum.
The white look of foliage on trees and grass in fields is because the chlorophyll in the leaves is transparent to very deep red and near infrared, and that either travels straight through or is reflected back by the plant cells. This effect is much the same as the way snow reflects light, hence the snowy look of infrared photographs. Water by contrast absorbs infrared so appears very dark or black.
In this photo of Slapton Ley the distant green fields appear snow covered, while the blue fresh water of the ley itself appears black. The reeds in the foreground were swaying in the breeze so the tops are blurred while the sheltered bases of the reeds are not. The horizontal white lines on the water are swans moving during the slow shutter opening.
We don’t know what infrared light actually looks like as we cannot see it. These photos are mere representations of infrared in a form that we can see thanks to the camera sensor. They are definitely caused by infrared light waves but because they have been "translated" into visible light that can only ever be an impression. We will never know for certain what infrared really looks like.
In 1800 the astronomer Sir William Herschel discovered that infrared radiation is a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer. Slightly more than half of the energy from the Sun was eventually found, through Herschel's studies, to arrive on Earth in the form of infrared. Any object which has a temperature radiates in the infrared. Even objects that we think of as being very cold, such as an ice cube, emit infrared.
The name “infrared” comes from the Latin prefix “infra”, meaning “below” and the word “red”. The word directly means "below red", which is exactly what infrared is in terms of its frequency. The infrared light ranges from near- to far-infrared, first being closer to the visible light and the latter - microwaves.
I failed to get this photo sharp as it was my first attempt, and I was also hampered by the fact that the sun was so bright I couldn't see the camera screen in much detail. Having said that, I actually like it as it has such an otherworldly appearance. The waves that were crashing onto the rocks have disappeared due to the slow shutter speed and have left the English Channel looking like the edge of a flat stony desert.
The red colour of these images is that designated by the sensor. It is also possible to render them in black and white.
Isn't that fun? Glad your tried it out because it really makes some crisp, sharp b&w images. Of course, as you pointed out, focus is an issue, but the wind is the biggest problem. I found that I had to make sure nothing that could move in the wind was within 10-15 feet - wider landscapes were much safer. I just got a variable IR filter (590-720nm) but can't try it out until all the storms pass (who knows when?).