The best camera for hand-held aerial photography is probably the one with which you are most familiar. This does not mean that you should disregard the excellent hand-held 70mm aerial cameras. If you have access to any of these aerial cameras, by all means give them a try. You may find them very much to your liking. These aerial cameras are top of the line and are capable of producing photographs of the highest quality.

What type of pictures are you going to take? What will they be used for? These factors have a big influence on what camera you select-35mm for slides or 120mm

Figure 4-13.-Photographer shooting from helicopter.

or 70mm for 16 x 20 inch or larger prints. There are many experienced aerial photographers, and because of varying experiences, they may have very different opinions. Most favor a medium-format camera when prints are required. Medium-format cameras are easy to handle in confined spaces-the back seat of a jet aircraft, for instance. They are relatively small and convenient to use. With careful processing and printing, almost any size of print can be made from the negatives produced by a medium-format camera.

Excellent results may be obtained by using a 35mm camera; assuming, of course, you handle the film carefully during processing and printing. Because of the variety of interchangeable lenses, small size, ease of handling, and large number of exposures, the 35mm camera is preferred by many Navy Photographer's Mates.

FILM SELECTION

Aerial film is designed for high-altitude photography and does not yield better results than conventional films at low altitudes. Remember that most hand-held aerial photography is performed at low altitudes. There are several factors that you must consider before selecting a particular type of film. The first, of course, is the end use (purpose) of the pictures. Do you need black and white or color; prints or slides? Other important factors are as follows:

Weather and haze conditions Lighting conditions

Special purpose film (color, camouflage detection, and infrared (CDIR)

Special filtration

Processing requirements or capabilities Black-and-White Panchromatic Film

For an aerial assignment requiring black-and-white prints only, you should first consider a black-and-white film, such as Kodak Technical Pan (Tech. Pan.). This and other similar types of film are fast enough for most aerial work when the weather is good and the subject is well-lighted. The extended red sensitivity of Tech. Pan. also helps to penetrate haze. This film is readily available and convenient to process. Tech. Pan. has excellent resolution and the extreme fine grain required to make high-quality enlargements.

Special types of film designed for reconnaissance are also available. These films are normally available only in rolls, and they range from 70mm to 12 inches wide. These films are characterized by their sensitivity, base type and thickness, speed, resolution, and granularity. These films also have an extended red sensitivity to aid in greater haze penetration.

Although black-and-white prints can be made from color negatives, it is better to use black-and-white film. Black-and-white film is superior to color emulsions in their ability to record image detail. Haze and contrast control are easier to achieve with black-and-white film than with color film (fig 4-14).

Black-and-White Infrared (IR) Film

In aerial photography, black-and-white infrared (IR) film offers several advantages over panchromatic film. Primarily it provides higher contrast and the unique ability to record detail through haze. Thus black-and-white IR film should be considered when aerial views must be taken under such conditions. This type of film can record more detail through haze than can be seen with the human eye. The sensitivity of IR film extends to approximately 900nm with maximum IR sensitivity from approximately 760nm to 880nm. It is particularly useful when extreme distances must be covered, such as high-altitude photography, or when a high angle of view is required for high obliques. Before selecting a black-and-white IR film, you should check with the person for whom you are doing the work Prints made from black-and-white IR negatives appear quite contrasty because blue sky and water are reproduced almost black fig. 4-15. Growing crops and deciduous trees appear white in photographs and most evergreens record darker. If such prints meet the requirements of the requester and IR film is the best choice, by all means use it. However, keep in mind that when black-and-white IR film is used, you must filter out blue and ultraviolet radiation with a red filter, such as a Kodak Wratten No. 25 or equivalent, for best results.

Color Negative Film

Color negative film, such as Kodak Vericolor III Type S, may be used to provide color and black-and-white prints. However, when available, film, such as Kodak Vericolor HC, is a better choice. Kodak Vericolor HC provides better results because of the

Figure 4-14.-Aerial photograph taken with black-and-white film without a filter.

increased inherent contrast and color saturation of the film. When a high degree of magnification is required, Kodak Ektar film can provide excellent results. Color negative film has much better exposure latitude and is more versatile than color reversal film.

Color negative film is often an excellent choice for aerial photography, particularly when you are unaware of some possible uses for the photography, or there is more than one type of finished product. Black-and-white printing paper, designed to be processed through color-chemical processes, can provide excellent results, and color slides may be made easily by copying color prints.

Color Reversal Film

When only color slides are required, you should choose a color reversal film, such as one of the Kodak Ektachrome films. This type of film comes in a number of ISO speeds and is excellent for making aerial slides.

High-speed color reversal film is useful for photography in the late afternoon or at dusk when the light level is low.

When you must take color pictures in a heavy haze or from high altitudes, contrast can be improved somewhat by having internegatives made from color slides. Color prints can also be made directly from color slides.

Infrared Color Film

Infrared color aerial photography is useful for obtaining photographic information that is not available through conventional photography. Ordinary color film has three emulsion layers that are sensitive to blue, green, and red light; IR color film is sensitive to blue, green, red, and infrared radiation. The result is transparencies that reproduce original scene colors differently for most natural features. IR radiation appears as red, green reproduces as blue, red reproduces

Figure 4-15.-Aerial photograph taken with black-and-white IR fihn and a filter.

as green, and blue reproduces as black (because the film is exposed through a deep yellow filter). Many other colors are also formed, depending on the proportions of green, red, and infrared reflected from the original scene. Infrared color film was designed for camouflage detection, and it shows differences in infrared reflectance between live, healthy vegetation and areas visually similar, such as pseudo foliage and camouflage netting. Color IR film should be exposed through a minus blue (deep yellow) filter, such as a Kodak Wratten No. 12 or equivalent.

CAUTION

Kodak Ektachrome Infrared film can not be processed in Process E-6. It must be processed in Process ME-4, Process EA-5, or Process E-4. Do not attempt to process Kodak Ektachrome Infrared film through any type of E-6 processor. This could impair the processor and ruin the chemicals.