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Digital Infrared Photography Explored: Part I
First in a series on specialty cameras for infrared photography.
by Cyrill Harnischmacher


A modified camera makes even snapshots possible. Infrared optimized Nikon Coolpix 5400, 28 mm, aperture 4.4, 1/500 sec., ISO 50.
Infrared action photography may be unusual, but it is indeed possible. Infrared modified Nikon Coolpix 5400, 36 mm, aperture 4.0, 1/1000 sec., ISO 50.
Because of its "Night Shot" mode, the Sony DSC-F828 allows handheld infrared shots. Photo: Claudia Gitter.
Sony DSC-F828, 35 mm, aperture 2.0, 1/60 sec., ISO 100, B+W 093 IR filter, 4 x gray filter. Photo: Claudia Gitter.
The Wood Effect makes trees a highly interesting subject. Infrared optimized Nikon Coolpix 5400, 28 mm, aperture 2.8, 1/1250 sec, ISO 50.
A castle's moat. The end of summer does not mean the end of infrared photography. Interesting subjects can be found even in winter. Infrared modified Nikon Coolpix 5400, 28 mm, aperture 4, 1/400 sec., ISO 50.

Beyond Production Cameras

Cameras can be optimized to work with much greater sensitivity in infrared light. There are several ways to do this, but in all cases the camera's internal infrared blocker is removed. Depending on the intended use, the blocker is replaced with either a sheet of clear glass, or with an infrared filter designed for a specific wavelength. Cameras so modified offer a tremendous advantage over regular production cameras. The improved light sensitivity results in short shutter speeds, which often reduces the need for a tripod. Handheld head shots and pictures of moving objects become possible without the typical blurring caused by motion. Replacing the internal infrared blocker with clear glass frees up the sensor's full sensitivity. We can still selectively remove unwanted wavelengths from the image by attaching the appropriate filters to the main lens. This makes photography in UV light possible, yet, the camera's ability to function in visible light can be restored with the correct filter.

If an infrared filter is permanently attached to the camera, it can no longer be used for visible light photography. Unless we select a filter that is close to the visible red light, the camera is narrowly restricted to a particular wavelength. For example, with a permanent 850 nm filter, shots in 715 nm are no longer possible, since this wavelength can no longer reach the sensor. But if we permanently attach a 715 nm filter, we can still use an 850 nm filter on the main lens to further restrict the spectrum as needed. This makes it possible to produce color images as well as pure black and white shots.

By following directions found on the internet, camera modification can be a do-it-yourself project, but this introduces the danger of causing irreparable damage to the camera. In some cases even the work itself may even be dangerous. Beware! If opening the camera exposes the capacitor for the flash, an unsuspecting home mechanic could receive a potentially lethal electric jolt. Recently, several camera companies have begun to offer professional conversion work, which also includes adjustments to the autofocus to ensure that the modifications do not result in blurry images. Of course, the original warranty becomes invalid in either case. It may seem prudent to convert a camera only after its warranty has expired anyway.

Special-purpose infrared production cameras are a different matter, however, as these are usually built for scientific and research purposes in extremely small numbers. One such example is the Canon 20D, which is built and optimized for astrophotography. Its internal infrared blocker allows heightened sensitivity in the h-alpha color band at 656 nm, which is barely in the visible red spectrum, making this camera perfect for astronomers. The SLR S3 Pro UVIR by Fuji has a much more transparent filter compared to the base model, and in combination with its 12 megapixel resolution, this camera delivers stunning details. Based on this camera, there is also its successor model S 5 Pro. The bridge camera Fuji IS-1 with a resolution of 9 megapixels is based on the Fuji FinePix S9500. This camera works between 400 nm and 900 nm.

All these camera models are great when it comes to combining infrared photography with conventional color photography. On the other hand, these specialty cameras are made in small numbers. Their high cost matches the cost of professionally converted conventional cameras. Also on the downside: these specialty cameras are not widely available, often disappear from the market, or they may only be offered in certain countries.

One model in particular, the bridge camera Sony DSC-F828, stands out because of its design. This camera's movable blocking filter can be snapped out of the way when it is not wanted for a particular shot. This camera also has a downside. Although the camera's "Night Shot" mode gives high infrared sensitivity, it also makes it impossible to select aperture and shutter speed. In bright sunlight, a gray filter is necessary.

OPTIMIZED INFRARED CAMERAS

Compact Cameras (with internal infrared blocker)

The internal blocking filter is permanently swapped for a fixed internal infrared filter. No additional filter is necessary on the main lens.

Advantages:
• High shutter speed
• No hot spot
• Adapter tube and threaded ring on main lens unnecessary

Disadvantages:
• Normal light pictures impossible

Compact Cameras (with clear glass filter)

The internal blocking filter is permanently swapped for a clear glass filter. An additional infrared filter is necessary on the main lens.

Advantages:
• High shutter speed
• The camera's ability to shoot in visible light is preserved if an infrared blocker is attached to the main lens
• A variety of infrared filters can be used

Disadvantages:
• Either an adapter tube or filter threading on the main lens is necessary
• Depending on the focal length, a hot spot can become visible in images

SLR Cameras (with internal infrared blocker)

The internal blocking filter is permanently swapped for a fixed internal infrared filter. No additional filter is necessary on the main lens.

Advantages:
• High shutter speed
• All lenses can be used without producing hot spots
• Focusing and setting up the shot can be done through the viewfinder

Disadvantages:
• Normal light pictures impossible

SLR Cameras (with clear glass filter)

The internal blocking filter is permanently swapped for a clear glass filter. An additional infrared filter is necessary on the main lens.

Advantages:
• High shutter speed
• The camera's ability to shoot in visible light is preserved if an infrared blocker is attached to the main lens
• A variety of infrared filters for different wave lengths can be used

Disadvantages:
• The viewfinder blackens when an infrared filter is attached
• Depending on the lens, hot spots may occur

Links to the second and third installments in our completed series are below:

www.imaginginfo.com/web/online/Online-Exclusives/Digital-Infrared-Photography-Explored--Part-II-/49$429

www.imaginginfo.com/web/online/Online-Exclusives/Digital-Infrared-Photography-Explored--Part-III-/49$4317

Excerpted from the new book release Digital Infrared Photography by Cyrill Harnischmacher and published by Rocky Nook. For more information visit http://www.rockynook.com.


   







PTN Dailes HERE