Wednesday, August 3, 2022


Frank Lloyd Wright's Rudin House: standard black and white image on the left, infrared on the right

No digital camera makes it as easy as the Leica M8 to use infrared light to create surreal pictures that stand out in radiantly bright green leafs in extreme contrast of a dark sky, for example.  As is known, the barrier filter of the sensor cover glass is very weak for design-related reasons.  Therefore an additional blocking filter is always recommended for normal photography to avoid a magenta cast of skin tones or black textiles. 
For infrared photography nothing more is necessary than an infrared filter like the B + W IR 093 Black Red 830 F PRO.  All B + W filters are made from high quality optically ground and finely polished, plane-parallel and streak-free glass.

For more versatility B+W offers two infrared filters.  The B+W 092 IR filter 695 looks almost black, but is deep purple-red in front of a light source. It blocks visible light up to 650 nm, and at just below 700 nm it allows 50% to pass through (hence the dark red color).  From 730 nm to 2.000 nm the transmittance is very high at over 90%. This allows shots of the pure red and IR image. This IR filter is suitable for most digital cameras.

The B+W 093 IR filter 830 blocks the entire visible light spectrum. It therefore appears black and in contrast to the B+W 092 infrared filter 695, it enables shots in pure infrared without the visible red. The transmittance does not exceed 1 % until 800 nm, but increases to 88 % at 900 nm.  The filter factor is highly dependent on the lighting. The optimum exposure value can be determined by running a series of tests.

Without B+W Infrared 093 filter

With B+W Infrared 093 filter

With B+W Infrared 093 filter - converted to black and white

Without B+W Infrared 093 filter

With B+W Infrared 093 filter

Since infrared filters have a very large exposure factor and therefore require long exposure times, it is always recommended to use a stable tripod.  Automatic exposure control should not be used because the exposure meter is calibrated for visible light only.  The optimum exposure values can best be determined through a series of tests. The distance settings require some practice as well.  As a rule of thumb for infinity focus under IR conditions multiply the focal length by 300.  For example, for a 50 mm lens that is 15 meters. Instead of using the infinity mark of the lens, set a 50mm lens to 15 meters.

These filters are available in sizes E39, E46, E49, and E55.

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