In the early and middle part of the twentieth century, most cameras consisted of two lenses that were vertically mounted to the front of the camera body. One lens enabled the operator to view the scene while the other recorded the image. Thus, these cameras were “twin lens” as opposed to “single-lens,” made popular with the advent of 35 mm film. The single lens cameras were also given the name “reflex” in reference to a pentaprism and mirrors inside the camera that allow the photographer to reflexively view the image through the same lens that permits light passage to the film. At the instant of exposure, the main mirror in the camera body flips out of the way so that light can travel unimpeded onto the film plane. A disadvantage of SLR cameras is that due to the necessary movement of the mirrors, the camera body tends to be large and frequently heavy. Without an attached lens, these cameras typically weigh between 18 and 33 oz whereas subcompact cameras weigh between 4 and 7 oz and compact cameras weigh between 6 and 19 oz.6 However, an advantage of this technology is that it allows for the use of a variety of lens and flash options. Several lenses, like the wide-angle zoom and macro (close-up) are easily attached to the SLR camera body and are useful for lesion characterization. Moreover, SLRs have also been favored in the past by those who require the ability to set the exposure manually in order to accommodate unique lighting situations. In regards to the new digital or DSLR cameras, many of the older lenses will still function with the new digital camera body as long as the manufacturer is the same. Still, there may be some minor formatting compromise due to the different field of view of the digital media. Some manufacturers, like Nikon™, Canon™, and Fuji™, have overcome this by introducing reliable and affordable digital SLR cameras that are compatible with their current non-digital gear. In general, the cost of good SLR and DSLR cameras ranges from $500 to $1,400 without lenses.

The other 35 mm format camera is the compact/subcompact or point-and-shoot. Several years ago, this camera was referred to as a “Rangefinder” since this was the focusing mechanism it employed. Currently, it is the overwhelming choice of digital camera purchasers in the world. The main advantages of this camera are its overall body size, LCD size, and economy. Because compacts do not rely on a mirror system, they are not limited to large body sizes and even when equipped with a zoom lens, a subcompact and some compacts will fit easily into a lab coat pocket – a feat that cannot be managed by an SLR. At times, the compact size can be problematic for clinicians with larger hands as buttons and dials on the camera are small. As a result, it is recommended that clinicians physically test cameras before purchase. They also have large LCD (liquid crystal displays) screens so that the photographer can preview and review a photograph. Often, LCD displays on the SLR cameras can only be used to review a picture taken, but they cannot be used for preview. Additionally, the average cost of subcompact and compact cameras tend to be much lower than that of SLRs. In general, they range in price from $100 to $450.6,10 Likewise, with recent advances in the art of lens manufacture, many of the enhanced compact cameras now compare favorably with the single lens reflex models for most medical situations. This is especially true if the purpose of the image is to document relative sizes and locations of lesions or defects. The majority of these models come equipped with zoom lenses that can offer a range of different focal lengths thus emulating, if not equaling, the chief feature of SLRs.

One shortfall of compact cameras is their flash capability. Most have a very small “pop-up” flash built into the camera body. Therefore, when shooting very close to or more than 9 ft from the subject, the flash can result in overexposure of the image or be considerably underpowered in lowlight conditions. However, these situations can be avoided by using the optical zoom capabilities of the camera while standing at approximately 4–5 ft from the subject.

Several manufacturers also offer a hybrid DSLR/compact camera which is thought of as “SLR-like.” This camera type is larger than most compacts due to the accommodation of a particularly un-compact-like lens. This lens, while larger and of a greater zoom capability than other compacts, is not interchangeable. Still, the larger lens may have a better close-up capability and the camera itself has an option for an auxiliary flash. Overall, the camera has the look of a DSLR without many of the inherent SLR disadvantages.

Zoom lenses are often used in smaller examination rooms to take full-body photographs of patients. This type of lens is especially useful in displaying the distribution and pattern of a whole-body rash.6 They are designed such that the internal elements can alter position and produce a variable field of view, thus capturing the entire area of focus. The majority of compact cameras come equipped with zoom lenses as standard equipment. Most SLRs, however, are sold with a normal lens and have the option of mounting other fixed focal length or specialty lenses like wide-angle zooms.

In general, most digital cameras contain both optical and digital zoom capabilities. An optical zoom is like that of an older film camera. The camera alters its focal length by changing the position of internal lens elements. The optical zoom is frequently favored over the digital zoom, because this camera utilizes high quality optic lens technology. What has commonly been referred to as “digital” zoom does not involve optics, but rather is an electronic cropping of the image in the camera’s viewfinder followed by enlargement. This in turn results in a lower quality image than a photo taken with an optical zoom lens. Therefore, it is better not to rely on digital zoom, but instead, use the digital camera’s optical zoom feature whenever possible.

Macro-lenses are used to focus the camera within millimeters of the lesion in question. This allows for certain characteristics such as texture and color to be visualized with great detail.6 If the dermatologist’s camera of choice does not have the mounting capability for different lenses (like SLRs), the built-in lens should be able to focus on up-close objects. Unfortunately, many lower-priced cameras are not manufactured with this capability.

For dermatologic surgery, it is most appropriate to have a macro-lens that can capture an image at a 1:1 (subject to film) ratio. At this setting, a photographed area would be reproduced at exactly the same size on the film or media card as in reality. For 35 mm film, the subject will cover an area that is 24  ×  36 mm; adequate for recording a small lesion. However, not all close-focusing lenses have a 1:1 capability. Therefore, it is important to ask about this feature prior to purchasing a lens.

Note that a lens that has macro capability also functions as a regular lens that is dependent on its focal length. This length will determine how far away the photographer can be while taking both normally-focused and macro pictures. At our facilities, we’ve determined that the most appropriate macro-lens length for obtaining photographs of patients and surgeries is 105 mm. This length allows for close focus of images while the camera remains at a reasonable distance from the site of interest. This also makes the situation more comfortable for both the patient and surgeon.