Full-frame Digital SLR - Advantages and Disadvantages of Full-frame Digital SLRs

Advantages and Disadvantages of Full-frame Digital SLRs

Full-frame DSLR cameras offer a number of advantages over their smaller-sensor counterparts. One advantage is that wide-angle lenses designed for full-frame 35 mm retain that same wide angle of view. On smaller-sensor DSLRs, wide-angle lenses have smaller angles of view equivalent to those of longer-focal-length lenses on 35 mm film cameras. For example, a 24 mm lens on a camera with a crop factor of 1.5 has a 62° diagonal angle of view, the same as that of a 36 mm lens on a 35 mm film camera. On a full-frame digital camera, the 24 mm lens has the same 84° angle of view as it would on a 35 mm film camera.

If the same lens is used on both full-frame and cropped formats, and the subject distance is adjusted to have the same field of view (i.e., the same framing of the subject) in each format, depth of field (DoF) is in inverse proportion to the format sizes, so for the same f-number, the full-frame format will have less DoF. Equivalently, for the same DoF, the full-frame format will require a larger f-number (that is, a smaller aperture diameter). This relationship is approximate and holds for moderate subject distances, breaking down as the distance with the smaller format approaches the hyperfocal distance, and as the magnification with the larger format approaches the macro range.

There are optical quality implications as well—not only because the image from the lens is effectively cropped—but because many lens designs are now optimized for sensors smaller than 36 mm × 24 mm. The rear element of any SLR lens must have clearance for the camera's reflex mirror to move up when the shutter is released; with a wide-angle lens, this requires a retrofocus design, which is generally of inferior optical quality. Because a cropped-format sensor can have a smaller mirror, less clearance is needed, and some lenses, such as the EF-S lenses for the Canon APS-C sized bodies, are designed with a shorter back-focus distance; however, they cannot be used on bodies with larger sensors.

In addition to wide-angle photography, another major advantage of full-frame cameras is pixel size. For a given number of pixels, the larger sensor allows for larger pixels or photosites that provide wider dynamic range and lower noise at high ISO levels. As a consequence, full-frame DSLRs may produce better quality images in certain high contrast or low light situations.

The full-frame sensor can also be useful with wide-angle perspective control or tilt/shift lenses; in particular, the wider angle of view is often more suitable for architectural photography.

While full-frame DSLRs offer advantages for wide-angle photography, smaller-sensor DSLRs offer some advantages for telephoto photography because the smaller angle of view of small-sensor DSLRs enhances the telephoto effect of the lenses. For example, a 200 mm lens on a camera with a crop factor of 1.5 has the same angle of view as a 300 mm lens on a full-frame camera. The extra "reach", for a given number of pixels, can be helpful in specific areas of photography such as wildlife or sports. This extra "reach" does come with the price of some loss of shutter speed, due to the aforementioned "crop factor". Teleconverters enable full-frame cameras to achieve a similar effect.

Production costs for a full-frame sensor can exceed twenty times the costs for an APS-C sensor. Only 20 full-frame sensors will fit on an 8-inch (200 mm) silicon wafer, and yield is comparatively low because the sensor's large area makes it very vulnerable to contaminants—20 evenly distributed defects could theoretically ruin an entire wafer. Additionally, the full-frame sensor requires three separate exposures during the photolithography stage, tripling the number of masks and exposure processes.

Some full-frame DSLRs intended mainly for professional use include more features than typical consumer-grade DSLRs, so some of their larger dimensions and increased mass result from more rugged construction and additional features as opposed to this being an inherent consequence of the full-frame sensor.