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 [graphic] National Register Bulletin: How to Improve the Quality of Photographs for National Register Nominations

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U.S. Department of the Interior, National Park Service

II. Cameras and Lenses

Thirty-Five-Millimeter Cameras and Lenses

The most common photographic equipment today is the 35-mm camera. There are several varieties, including: fully automatic cameras, commonly called "point-and-shoot" cameras; single-lens-reflex cameras, and range-finder cameras. Many people use "point-and-shoot" cameras. They are fully automatic; some have a manual override feature. Their price ranges from $50 to $1,000. The more expensive models have more features. Most "point-and-shoot" cameras have a moderately wide-angle 35-mm lens, useful for architectural photography, particularly in tight urban settings. However, this lens can increase distortion when used fairly close to the subject if the camera is not leveled.

Point and Shoot Camera 35-mm Single-Lens-Reflex Camera Rangefinder Camera
Point-and-Shoot Camera. (Frederic Athearn, 1995) 35-mm Single-Lens-Reflex Camera. (Frederic Athearn, 1995) Rangefinder Camera. (Frederic Athearn, 1995)

"Point-and-shoot" cameras are not particularly suitable for photographic documentation, because they cannot be easily adjusted for variations in lighting, or difficult lighting situations. While they meter light automatically, they sometimes meter it inaccurately. In difficult or unusual lighting conditions these cameras will simply not provide a good photograph. Under normal conditions, with bright light, "point-and-shoot" cameras will provide adequate photographs for National Register nominations. "Point-and-shoot" cameras work best outdoors, in bright light, using a moderately fast film (ISO 200). Normally the built-in flash for a "point-and-shoot" camera is low-powered, making it unsuitable for interior shots. Where there is backlighting (see Glossary for definition) or low lighting, "point-and-shoot" cameras may not produce good photos. (More expensive models may have override features or better flash units that can overcome these problems.)

A better choice for documentary photography than a "point-and-shoot" camera is a single-lens- reflex (SLR) camera. With this camera, you look through the camera lens, making framing and focusing very easy. The lenses are usually interchangeable, so various focal lengths can be used. Another advantage is that shutter speeds and lens openings [f-stops] are adjustable, either manually or automatically.

There are a few range-finder-type 35-mm cameras (i.e., Leica M-6, Contax G-1, Konica, etc.) with interchangeable lenses available, but they are expensive. Instead of looking through the lens, as in the SLR, you sight through a range-finder prism on top of the camera. Focusing for the range-finder is very accurate. Some people have trouble using the frames in the viewfinder to compose their pictures because of the frame outlines seen through the viewfinder. These outlines represent the area of actual view. They are called bright frames. Each one represents a different focal length in the viewfinder. Range-finders also suffer from parallax problems. Parallax is the difference seen between the viewfinder and the lens. At infinity, there is no significant problem. The closer you get to the subject, the more parallax occurs. The photographer may see the complete image in the viewfinder, but because of parallax, the lens fails to capture the entire subject. (See Glossary.)

A normal lens for a 35-mm camera is 50mm in focal length. It is called normal because the angle of view is approximately the same as the human eye. A 50-mm lens is usually the lens sold with the camera. It is perfectly usable for documentation. However, a wide-angle (24-mm to 35-mm) lens gives the photographer a wider view of the scene, taking in more of a building, for instance. Wide-angle lenses may induce distortion. The greater the angle, the greater the distortion. Lines tend to curve and parallels converge. A cheaper lens has more distortion than an expensive, highly corrected lens. The wide-angle lens is useful for photos in tight places, for interiors, or for photographs where the whole image cannot be composed on film without a wider view.

photograph comparing 2 photograph techniques
The photo on the left was taken using a Zeiss Distagon 60mm lens. The one on the right was taken with a Zeiss Distagon 40mm lens plus Zeiss PC-Mutar 1.4x Shift Converter for Hasselblad. Without the PC lens the building appears to be leaning backward. (Photos courtesy of Hasselblad. 1990)

On the other hand, moderate-to-long (100-mm to 400-mm) telephoto lenses are sometimes useful for documentation. When it is possible to get back far enough from a building to use a telephoto lens, the perspective created by that distance is very pleasing. Distortion of the property is minimal. Lines are straight and parallels do not converge. Telephoto lenses are also useful for photographing a site from a distance that is not accessible for closeup documentation. However, atmospheric haze and heat effects may interfere with the clarity of images taken with a telephoto lens. Use a telephoto lens with caution. Generally, image quality is not as good as could be obtained close up, but telephoto lenses are really useful for occasions when one cannot get up close to a feature or detail. The longer the lens, the greater the need for a tripod.

Zoom lenses are another type of lens that can be useful in photographing historic buildings and landscapes. Zooms are very common for 35-mm cameras. They range in focal length from 20-60mm to 200-500mm. The most common is probably 35-70mm and 70-200mm. Zooms are very versatile, providing the photographer with a range of focal lengths from which to choose. The primary virtues of a zoom lens are convenience and choice. Cheaper zoom lenses fail to produce images of sufficient sharpness for National Register standards.

Perspective correction (PC) or shift lenses are made for both 35-mm and medium-format cameras. They can be used in architectural documentation to eliminate convergence. These lenses usually are moderately wide-angled (24mm) and shift side-to-side and up and down. Some perspective correction lenses also tilt, like a view camera. (See camera descriptions.) The advantage of this type of lens for the photographer of architecture is that it can be moved to correct perspective, convergence, or distortion. In the case of converging parallel lines, for instance, the lens can be moved off its axis to correct the lines. PC or shift lenses are mandatory equipment for quality small-format architectural photography. Currently, both Nikon and Olympus provide the flexibility of offering both 35mm shift lenses as well as other wider-angle shift lenses. Several other manufacturers produce shift lenses for their SLRs in a single focal length, most often 35mm. Perspective correction lenses or cameras should be used with a tripod and level or the benefits they offer are negated.

Most 35-mm films end up at a drug store or a photo shop to be developed, where machine prints are standard. Black and white prints are required for nominations. While it is somewhat more expensive (about 25 percent on the average) and usually more time-consuming to have stable, permanent 35-mm negatives and prints made, it is worth some extra expense, because the goal is long-term storage and retrieval of these materials. Black and white photographs produced by machine processing are marginally stable (perhaps fifty years). However, they may be submitted with National Register nominations provided they contain no evidence of residual chemicals, fading, or yellowing.

The 35-mm camera is easy and quick to use, but a 35-mm negative does not provide the level of detail and quality that a negative from a larger format camera can. Small-format films stretch the limits of resolution (resolution is measured in lines per millimeter) and sharpness. Most 35-mm single lens reflex cameras have very good lenses on them. But when a 35-mm negative is enlarged to 8 x 10 inches or 11 x 14 inches, the image undergoes degradation to the point that important details can be lost.

For photographic documentation where color slides (transparencies) are needed, 35-mm film is helpful. Using Kodachrome film (for long life), a 35-mm slide gives the viewer an idea of the tones and shades of a structure and what the environment looks like; however, using slides is NOT an acceptable substitute for archival black and white negatives and prints. (Color slides are required in the formal review of National Historic Landmark nominations.)

Medium-Format Cameras and Lenses

Single Lens Reflex Camera
6 x 6 cm Single-Lens-Reflex Camera with lens shade. (Frederic Athearn, 1995)
Twin lens reflex camera
Twin-Lens-Reflex Camera. (Frederic Athearn, 1995)

A medium-format camera is superior to a 35-mm camera for recording historic resources that may be eligible for inclusion in the National Register of Historic Places. The medium-format camera captures details and allows for greater enlargement of negatives than the 35-mm camera without significant quality loss. Medium-format refers to cameras that use 120/220-size roll film. Medium-format photography is a compromise between small (35mm) format and large (a 4- x 5- inch) format negatives. Most working photographers acknowledge the superiority of a medium-format image over a small-format image.

By definition, any camera that uses 120/220-size-roll films is medium format. Standard medium formats are 6 x 6cm (2 1/4- x 2 1/4-inch), 6 x 7cm, 6 x 8cm, and 6 x 4cm. Using a medium-format camera, a photographer can make a detailed record of a historic property without the expense and difficulty of a 4 x 5, or larger, view camera. Medium-format equipment is also more commonly available and easier to use than large-format equipment.

The same comments that apply to 35-mm cameras regarding wide-angle lenses and telephoto lenses apply to medium-format cameras. Their use is seriously limited in architectural photography because normally they cannot be shifted to correct for distortion and perspective. Most current manufacturers make lenses for medium-format cameras that can be shifted called perspective correction or "pc" lenses. Perspective correction lenses are necessary for photographers using a medium-format camera to photograph architecture. They are expensive and they do not provide as much shift movement as a large-format view camera, nor do they offer as much shift movement or as wide an angle-of-view in their formats as do 28-mm or 24-mm shift lenses in the 35-mm format. Some currently available medium-format cameras that have interchangeable lenses (and in some cases, removable film backs) include: Hasselblad, Bronica, Mamiya, Pentax, Rollei, and Fujica.

Older, medium-format cameras like the Twin-Lens-Reflex are sometimes found in the closets of small museums and historical societies. Twin-Lens-Reflex (TLR) cameras were once the standard cameras for 2 1/4- x 2 1/4-inch negatives. Now Single-Lens-Reflex (SLR) cameras have replaced them. While TLRs do not have removable film backs, or interchangeable lenses, they are perfectly usable for photographing architecture. (Today, there are only two TLRs on the market, the Rolleiflex and the Mamiya Twin Lens. The Mamiya Twin Lens offers interchangeable lens capability, while the Rolleiflex does not. (Both of these cameras are 6- x 6-cm format.)

Wood Field Camera
4- x 5-inch Wood Field Camera. (Frederic Athearn, 1995)

Large-Format Cameras

Large-format cameras commonly have film formats of 4- x 5-inches; less common is 5- x 7-inch. Many commercial studios and art photographers use 8- x 10-inch film. The primary virtue of the large-format camera is that it is fully adjustable. It will swing, tilt, shift, and move in almost any direction. It is the best camera for architectural photography, resulting in fully corrected photographs.

The three most common types of large-format cameras are the view camera, the field camera, and the technical, or press camera. A view camera is basically a unit with a front standard and a rear standard, with light-tight bellows in between, mounted on a rail or board. It can weigh as much as 20 lbs. The lens is on the front and the film holder is on the rear. The subject is viewed from the rear of the camera on a ground glass back. The viewed image is reversed and upside down. A heavy duty tripod is essential to hold a view camera steady.

Film for a large-format camera comes in cut-to-size sheets, not rolls. The film sheets go into light-proof film holders that are inserted at the back of the camera. The dark slide is removed, the film exposed, and the slide is replaced. (All film loading and unloading from the film holder(s) must be done in total darkness.)

The field camera differs from the view camera. It is basically a box with a drop bed to which the front standard and bellows are lowered. This camera is very compact, lightweight, and portable compared to the view camera. A wooden 4 x 5 field camera can weigh less than 3 lbs. A lighter tripod can be used with a field camera, reducing field weight. A field camera may have fewer moves than a view camera, but for most architectural purposes, it is perfectly adequate. Viewing and film exposure occur exactly in the same way as a view camera. Field cameras are popular with photographers who must hike into remote areas to take photographs.

A technical camera (or a press camera) is very similar to a field camera, except that it is heavier and may have features like a rangefinder. It also has more limited moves, in particular, shift and tilt abilities. There are many old press cameras available, the Speed Graphic for one, that are usable for producing 4 x 5 photographs.

The primary advantage of using a view or field camera is that architectural perspective corrections are easy to make. Also, the large-film-format gives sharper, more detailed images. A 4- x 5-inch negative, for example, needs only twice the enlargement to produce an 8- x 10-inch print. A 35-mm negative, on the other hand, needs eight times greater enlargement to produce an 8- x 10-inch print. A good 8- x 10-inch negative can be greatly enlarged without losing quality. An 8-x 10-inch contact print can be absolutely exquisite. It has a quality like no other photographic print.

Digital Cameras

A new and promising development in the field of photography is the digital camera. This camera is being used increasingly to record historic structures for publication. Since the 1980s, digital photography has developed as a means to store, view, and manipulate images without film. Images are stored in the camera's memory or on disk; the images are then downloaded for viewing on a computer. Digital images can easily be posted to the Internet or distributed via electronic mail.

Basic Tips on Lenses and Filters

Tripods and Hand-Holding the Camera.

The use of a good tripod will eliminate camera movement-resulting in a sharper image. This is particularly true if you are using a 35-mm camera. If you must shoot without a tripod, shoot at the highest possible speed to reduce camera shake. When you use a telephoto lens longer than 135mm, you should have the camera on a tripod. The longer the lens, the greater the shake. A general rule is, if you must handhold a long lens, your camera speed should be at least two times the length of the lens. For example, a 200-mm lens should be shot at 400th of a second.

Filters and Hoods.

Lens Hoods
Lens Hoods (Shades). L. rubber, clip-on type. R. metal, screw-on type. (Frederic Athearn, 1995)

High quality filters can improve photographs of architecture by enhancing details and bringing out surfaces that might otherwise go unnoticed. One of the most useful filters is a medium yellow, which increases contrast and helps to define the texture of wood, brick, and other surfaces. Orange and deep-yellow filters increase the effect even more. Green filters enhance foliage and plants, while a red filter can provide dramatic contrasts between dark and light areas. Photographs shot with a red filter can also provide more details when shooting masonry and poured concrete. A filter mounted over a lens will always degrade image quality somewhat, so use quality filters to reduce light and contrast loss.

Another useful filter for the photo-grapher is the polarizing filter, for reducing or eliminating reflection. This is particularly helpful if the photograph includes bodies of water or large areas of glass. Using a polarizer makes it possible to shoot through glass or into a situation where there is considerable glare. Polarizers can also increase contrast and/or darken blue skies in black and white photography.

All lenses with filters require exposure compensation, because they transmit less light than an unfiltered lens. A camera with a built-in light meter can calculate the correct speed and aperture. Because of light loss, working speeds and/or apertures will be lower than they would be without a filter. When using hand-held meters and cameras without light meters, the photographer must calculate the filter factor to assure properly exposed images. For example, if a medium-yellow filter has a filter factor of 2X, the f/stop must be increased by two stops or decreased by 2X. That would mean without a filter, you might be shooting at f/8 at 1/125th second. The f/stop is reduced to f/4 or reduced to 1/130th of a second to compensate for light loss from the filter. Again, if the camera has a through-the-lens metering system, compensation occurs automatically.

A simple, cheap and effective way to increase photographic quality is to use a lens shade (hood) for all shots. A lens hood should always be used on all lenses and cameras because it reduces flare and distortion and results in sharper, crisper photographs. Hoods also protect the front element of a lens from damage or from water when working in adverse conditions.

It is critically important to keep lenses clean, because dirt and fingerprints decrease contrast and sharpness. Dust should be blown off a lens, not rubbed off. If gentle blowing does not work, wipe the lens carefully with a special cleaning tissue available at most camera stores. Use cleaning fluid formulated for photographic lenses only. Use it sparingly to avoid loosening the lens elements or damaging the delicate multi-coatings. Dampen the tissue with the lens cleaning fluid. Apply with a circular motion. Finish with dry lens tissue. Do not ever rub a lens surface with an ordinary cloth; it will put tiny scratches in the lens coating. Camera manufacturers do not recommend using canned, pressurized air to blow off dust because the air pressure can damage lens surfaces, mirrors, and focusing screens. The best protection is to keep a UV or skylight filter screwed onto the lens more or less permanently.

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