Get a handle on the technical requirements when taking infrared photos with a digital camera from this excerpt of Cyrill Harnischmacher's Rocky Nook book.
This excerpt from Digital Infrared Photography is provided courtesy of Rocky Nook. To purchase the book and learn more about the publisher, visit the Rocky Nook website.
White Balance, Exposure, and Settings
Let’s jump right into the technical aspects, especially the control settings of the camera and on the lenses. Infrared photography is not a quick affair. There will almost always be a need for special preparations before the first shot is taken. We should not dismiss this as a disadvantage, but rather view it as an opportunity to immerse ourselves in picture composition.
RAW, JPG, or TIF
Especially in infrared photography, the RAW format has a lot of advantages over other data formats such as JPG. RAW files are minimally processed and are sometimes referred to as the digital equivalent of a film negative. They are the best platform for further processing or conversion into other file formats. The superior image quality resulting from RAW files compensates for their disadvantages, such as the large data volume and a more time-consuming workflow. If the camera does not offer a RAW setting, the next best format would be TIF. JPG files have undergone compression and have the smallest file size, but the compression process results in a slight loss of image quality. Regardless of what file format is selected, the need for good exposure control is paramount. It is better to expose on the low side, because this leaves more processing options for later.
For ideal image quality, the highest resolution should be set in combination with the lowest ISO setting. Of course this makes the shutter speed longer and can cause more image noise, but this is still preferable to the loss of image quality at a high ISO setting. Because of their smaller sensor size, compact digital cameras are especially afflicted by this dilemma. Some camera models already reach their limits at 400 ISO. As a consequence, attempting to compensate for long exposure times by raising the ISO setting really offers no solution.
The automatic white balance will, depending on the kind of filter, cause a more or less pronounced reddish tint. Sometimes the red channel will be completely maxed out, which is sometimes difficult to correct through image processing. Performing a manual white balance before shooting is well worth the effort. In regular color photography this can be best achieved by pointing the camera at a neutral gray card or white paper. This exercise will produce natural colors and a good gray balance. In infrared photography, a sunlit lawn or green foliage replaces the gray card, because the result should be pictures in which green plants will be rendered white or neutral.
The camera's histogram display should be used for improved control. Most light conditions are almost impossible to evaluate from the camera's viewfinder image alone.
Of course, the white balance must be done with the infrared filter in place. One potential complication is that not every camera will accept such a white balance on the first attempt. It might be necessary to choose a manual setting and experiment with somewhat slower shutter speeds. Depending on the camera model, these settings may be saved, or it may be necessary to save a reference picture on which the given settings are noted. When working with several filters, it is a good idea to save a reference picture for each filter, and then lock the files to ensure against accidental deletion. This makes it possible to refer back to these test shots.
Some cameras do not allow an individual white balance. In these cases it is best to select a white balance setting as close as possible to the red band. This counteracts an overexposure of the red wavelengths. If the camera allows files to be saved in the RAW format, it is also possible to perform the white balance during the RAW conversion at a later point.
Windmill. Nikon D70s, 24mm, aperture 8, 4 sec., ISO 200, Heliopan RG850. This filter, combined with a manual white balance, will lead to pure black and white images.
Aperture and Shutter Speed
Unless a camera has been modified for infrared photography, it is best to select the exposure settings in manual mode. Some experiments may be necessary to find the right shutter speed. Although the camera’s internal light meter will detect infrared light, the automatically calculated values are prone to error. This is a problem especially with cameras requiring double-digit seconds of exposure time. Sometimes, the best solution is to make a series of shots with varying shutter speeds. This way, an ideally exposed shot can be selected later. Even when the RAW format is used, the best raw material for a later conversion is an ideally exposed image. As a rule a tripod should be used, especially when several shots are taken and meant to be composited into one image later. With modified cameras the automatic setting is a good choice. Again, care should be taken to avoid overexposure. Even underexposure is preferable. Perhaps an underexposure of 1/3 or 2/3 f-stops less could be considered a benchmark. Preset exposure programs will usually fail to produce good results.
Users of digital SLRs will have to make do without autofocus. It will be necessary to focus without the infrared filter and then correct for focus aberrations manually. If the lens is not apochromatically corrected but has infrared markings, the necessary focus corrections are easily achieved by manually adjusting to the corresponding markings. On lenses lacking these markings, it is possible to add them. A narrow strip of adhesive paper imprinted with millimeter markings should do the trick. After attaching it to the lens, we can do a series of test shots adjusting the lens by one-millimeter increments each time. After determining the best focus setting on the LCD screen, markings can be made on the lens. This procedure is not needed with digital compact cameras. In most cases, their autofocus system will also work with the infrared filter attached. Small focus aberrations matter less with these cameras anyway since their smaller sensors have a much smaller depth of field to begin with. Whenever a camera is modified for use with infrared light and the camera is outfitted with a fixed filter, the autofocus must be calibrated. This is another reason why the conversion is best left to professionals.
If there are no IR markings on a lens, a strip of millimeter ruled adhesive tape could be affixed and marked after taking a few test shots.
Even when the camera is mounted on a tripod, it can easily be disturbed by vibrations. This is why remote shutter releases are immensely helpful. The best solution would be a wireless infrared remote control. Some cameras do not allow remote shutter control. If this is the case, the only option is the camera’s timed-release setting. Motion blur is often a result of long exposure times, for instance when the wind moves tree branches. This problem can only be avoided by patiently waiting for a calm moment.
Hotspots are a problem we can run into with all types of cameras and are usually seen as circular, brighter spots in the center of the image. The size will change with the aperture settings. The culprit lies in reflections between the camera’s sensor and the glass surfaces of lenses and filters. Owners of digital SLR cameras have the option of trying a different lens. But, if the hotspot appears in a digital compact or bridge camera, there really is no other solution but to attempt a removal with image-processing software. Only modified infrared cameras with internal IR filters do not suffer from this effect and can use all kinds of lenses.
Unfortunately, a hotspot is clearly visible in the center of the image. Fuji S3Pro, Nikkor 1.8, 50mm, Heliopan RG715.
This shot, made with the same lens and the same filter, but with a different camera, has no hotspot. Nikon D70s, Nikkor 1.8, 50mm, Heliopan RG 715.
Apart from the Wood Effect on green plants and the bright, waxy appearance of human skin, there are many other materials which will look quite different in infrared light. Synthetic fibers in particular, but also some cotton fabrics, are strong reflectors of infrared light and will therefore appear almost white regardless of their color in visible light. In general, colors lose not only their properties but also the gray value our sense of sight associates with each color. This makes it somewhat difficult to predict what an infrared shot will look like. For example, the attire of people at a wedding may lead to rather surprising results. It is therefore quite possible that the groom's suit turns from black to white when photographed in infrared light. The amount of reflected infrared light depends not only on the fabric material, but also on how it was dyed. Such unpredictable surprises can only be avoided by taking test shots.
Materials that have matching colors in visible light may look completely different in infrared.
Black cats are always black—even in near infrared. But the chair and the black pillowcase appear white in infrared.
Infrared Filter Comparison
The proportion of daylight is relatively high. The Wood Effect is visible, but not very pronounced with this type of filter. This filter is best for creative color experiments. Handheld shots are still possible with high ISO settings, a large aperture, and bright light. The viewfinder of an SLR camera will show a red tint.
The Wood Effect is quite visible. The RG 715 is suitable for both “color” and black and white infrared shots and is therefore ideal for novices. A tripod is necessary, because the shutter speeds are too long for handheld shots.
This filter shuts out most daylight. Whatever remains after performing a white balance will produce a brownish tint, which can be an attractive basis for a faint tone. A tripod is necessary.
This is a full infrared filter. After a manual white balance, this filter will produce only black and white pictures. Even in bright sunlight, the exposure times are quite long. Accordingly, there is a high possibility of motion blurring, which could also be used creatively.
Automatic White Balance
Left: Unprocessed image. Right: Automatically adjusted in RGB mode. Camera: Nikon D70s, Filter: Heliopan.
Manual White Balance
Left: Unprocessed image. Right: Brightness automatically adjusted in LAB mode.
Regular daylight shot. Nikon D70s, 24mm, aperture 6.3, 1/500 sec., ISO 200, white balance for sunlight.
Infrared shot. Nikon D70s, 24mm, aperture 6.3, 2 sec., ISO 200, Heliopan RG780, manual white balance for green grass in sunlight. Conversion in LAB mode, manual correction of brightness, channel swap of red against blue in RGB.
The lush tree turns into an abstract sculpture concentrating all lines at the center. Infrared modified Nikon Coolpix 5400, 28mm, aperture 3.2, 1/200 sec., ISO 50.
Shot against the sun, the foliage lights up while the trunk turns into an almost black silhouette. Infrared modified Nikon Coolpix 5400, 28mm, aperture 2.8, 1/1000 sec., ISO 50.
Country road. The RG715 filter lets more daylight pass through, and is therefore ideally suited for “color“ infrared photography. Nikon D70s, 24mm, aperture 4.5, ISO 200, Heliopan RG715.
Composing and Setting Up Shots
To a large degree, infrared photography equates to landscape photography. This is where we find some of the most amazing things to see in infrared light. While the principles of conventional photography fully apply, we may of course, from time to time, forget about the rules and go wild with creative freedom. But the qualities of classic photography—composition, abstraction, and focusing on the essential—have the same importance in infrared light. However, there are a few special considerations: For one, we must consider the Wood Effect and pay close attention to contrasts that are likely to result from it. As an example, let’s think about colorful flowers on a green, grassy meadow, which would look great as a color photograph. Using appropriate filters, this could also make an interesting black and white picture. But in infrared, the same meadow will yield only a bland area with little structure, because the colorful flowers and the grass reflect infrared light in quite similar ways. But, what if we choose a different perspective and shoot the flowers from below and against the clear sky? In infrared light the flowers will contrast well against a dark background. This example demonstrates the importance of the camera position. The best course of action is to contemplate several perspectives before taking a shot.
In this shot, the rainbow colors of the kite disappear and the kite is reduced to a graphic symbol. This kind of shot is only possible with modified cameras capable of high shutter speeds. With longer exposures, even the smallest movements of the kite would cause motion blur.
One reason is that we just might find a better angle, but another benefit is that this kind of thinking ahead makes us more aware of why we chose a particular perspective in the first place.
The motion blur caused by long exposure times in windy conditions can produce patterns similar to brush-strokes in modern paintings.
Another aspect of infrared photography is the tendency toward motion blurring, which is a result of the longer exposure times in infrared. Then again, this problem can be turned into a creative tool. A blurred swish can depict the movement of objects in a still picture by pointing out the contrast between moving and stable elements. In this way, the flow of water in a creek or trees moving in the wind in front of a building can suggest motion while at the same time accentuating the static part of the picture.
Since modified cameras will use fast shutter speeds even in infrared light, a gray filter on the front lens would have to be used when playing with these motion shots.
The Moonlight Effect
Shooting the clear sky with the sun behind our backs will produce an almost black sky. With low exposure, this can create the impression of a night shot, and something we call the “moonlight effect.” This effect can be amplified by choosing the appropriate subjects. Because too much sunlit foliage does not work well with these kinds of pictures, the winter months can provide the perfect occasion for this type of photography, contrary to the myth that winter is not “infrared season.” It is a good idea to experiment with several varying shutter speeds.
Even though this picture was taken in bright sunshine, the moonlight effect makes it appear to be a night shot.
The Soft Focus Effect
A deliberate defocusing during the exposure draws a shining aura around the bright parts of the picture.
Kodak HIE 2481 is a popular film in analog infrared photography. It lacks a protective layer and delivers wonderfully smooth light overwash. With digital capture, we can approximate the effect of this film (at least partially) either while taking the shot, or through later processing. The simplest method at the time of shooting is the use of a suitable soft filter attached to the front lens.
Another interesting possibility to achieve a softening effect is the double exposure. This technique exposes the image twice: the first time in normal focus, to be followed by another shot with the lens set to be more or less out of focus. Not all cameras allow double exposures. But as long as the focus can be set manually, we have another option. First, we place the camera on a stable tripod and focus normally. After setting a small aperture to correspond with several seconds of exposure time, it would be a good idea to take several test shots to make sure the settings are correct. After making sure we are good to go, we can release the shutter. Now here comes the trick: at the midpoint during the exposure, we “defocus" the lens by carefully turning the manual focus ring. Of course, this will cause some camera shake, but this is quite irrelevant because the picture resulting from this technique will be blurred anyway. The softening effect can be adjusted by defocusing earlier or later during the shot, which leaves the picture at varying degrees of base focus. In addition, the level of defocusing also plays a role. By noting all the settings together with the shot number we can reproduce the same effect on future occasions.
The picture’s overall harmonious, tripartite composition demonstrates the rule of thirds: the important elements are placed at the intersections of three vertical and three horizontal divisions. Infrared modified Nikon Coolpix 5400, 28mm, aperture 4, 1/500 sec., ISO 50.
Some digital cameras can show a guide grid in the viewfinder or on the LCD display, which is helpful for finding the right composition.
This picture not only shows tension between opposing forces; it also tells a story.
Whatever we do, special effects should never cause us to forget about classic photographic techniques. We should think about unusual perspectives and make them an integral element of our composition. The viewer can be guided into the picture by making use of existing lines, which can direct the viewer’s eyes to the most important details. We should also think about how to integrate the foreground into our compositions. Let’s not shoot only from eye level. Instead, we should look for camera positions and angles that not only show the subject in the best way, but also eliminate unwanted details. We should not only incorporate contrasts between bright and dark, but also between emotional tensions and opposing shapes. We can try both the vertical and horizontal formats and experiment with various focal lengths to find the combination that gives our subject the best depth and appearance.
Shot through a short telephoto lens, from an elevated location across the street, this shot includes all the important elements, but looks rather bland.
Try as we may, there will always be an element of uncertainty and surprise. After all, with infrared we are photographing something “invisible.” Of course this is exactly what makes infrared photography so fascinating and exciting.
This shot, looking up from the tower's base, was taken with a wide-angle lens. The vertical format works much better; the shorter focal length and the different perspective lend a much more dynamic quality to this image.
The Neckar River in Germany. Even in infrared light, reflections make an interesting and rewarding picture. In this case, the viewer’s eye is drawn into the shot by a nearly symmetrical arrangement and the central perspective. Nikon D70s, 24mm, aperture 8, 3 sec., ISO 200, Heliopan RG780.
Dunes and wind turbine. Color can also be a style element in infrared photography, but it is best used sparingly. Nikon D70s, 24mm, aperture 2.8, 1/2 sec., ISO 200, Heliopan RG780.
Dune grasses at the North Sea. In later processing, swaps of the red and blue color channels produce a partially blue tint. Nikon D70s, 28mm, aperture 5, 2 sec., ISO 200, Heliopan RG780.
Water lilies. Surreal-looking water lily stalks, an unusual perspective, and the luck of having an airplane streak across the sky all contribute to this shot’s appeal. Infrared modified Nikon Coolpix 5400, 28mm, aperture 3.2, 1/200 sec., ISO 50.
Tree in Schoenbuch. The position of the sun directly behind the camera turns the clear sky into an even black. Infrared modified Nikon Coolpix 5400, 80mm, aperture 6.3, 1/90 sec., ISO 50.