Photography Tip—How To Select a Digital Camera Based on Its Sensor Size
Because digital photography was preceded by the film era, many long-time photographers remember fondly the full-frame dimensions of 35mm film, which is 24mm x 36mm. The major camera manufacturers, such as Nikon and Canon, remember those days too, which is why they offer a number of full-frame digital camera models. It might seem, therefore, that serious photographers would want DSLRs with full-frame sensors, but that is not necessarily an obvious first choice.
This PhotographyTalk.com article will weigh some of the pros and cons; but, first, some background on sensor sizes in digital cameras. The smallest sensors are found on compact, point-and-shoot cameras, approximately 4mm x 5.25mm to 6.6mm x 8.8mm. The next group is based on the Olympus Four/Thirds system, which is 13.5mm x 18mm. That is typically the smallest sensor size on a DSLR camera. Most DSLRs are in the third group, known as APS-C. Their sensors are approximately 21mm to 24mm at the longest dimension. The last group, digital cameras with full-frame sensors, has the largest dimension, the 24mm x 36mm measurement of film cameras.
Although most of the remaining information in this PhotographyTalk.com article applies to DSLRs, and models with full-frame sensors, in particular, it is still important information to understand even if you’re planning to buy a compact.
Pros and Cons of Full-Frame Sensors in DSLR Cameras
Although a bit simplistic, a larger sensor creates less noise in an image, which is one of the advantages of any DSLR compared to a point-and-shoot. A much more important advantage of DSLRs with a full-frame sensor is that any lenses originally manufactured for 35mm film cameras have no “crop factor.” For example, a 28mm lens on a full-frame DSLR and a 35mm camera has the same capture angle. Full-frame becomes an excellent choice in a DSLR if you have a number of Canon lenses, especially wide-angles.
No crop factor is certainly an important characteristic when deciding on a full-frame DSLR, but optical aberrations, such as vignetting, corners with soft focus and edge distortion, should also be considered. Typically, the better the lens, the fewer the imperfections, and they can be eliminated entirely by changing aperture. Inexpensive lenses can accentuate aberrations and be reproduced in digital photos at almost any aperture setting. True, distortions in images shot with low-quality lenses can be fixed in Photoshop, but usually you lose part of the picture to cropping.
Crop factor can be an advantage because aberrations and distortions at the edges and corners of the frame are eliminated when you position your subject in the sweet spot in the center of most lenses. Now, an average or below-average lens originally meant for a 35mm camera can be used with a newer DSLR with an APS-size sensor, and produce satisfactory images. Another advantage, especially when using a telephoto lens, is that a 200mm lens on a DSLR has the same capture angle as a 300mm lens on a 35mm film camera.
The disadvantage, or con, is using a wide-angle lens, which is what serious hobbyists and professionals shoot most of the time. Essentially, the opposite effect occurs. For example, a 28mm lens has a capture angle of 42mm. An expensive and untidy solution is to purchase a 18mm wide-angle lens, but your maximum aperture will be smaller. Digital noise is another factor. It’s doesn’t exist on most DSLRs at ISO 800 or less. Select a higher ISO setting and you’ll see noise in photos from any DSLR, full-frame or no.
Keep in mind that some manufacturers market lenses exclusively for digital camera bodies with APS-size sensors. That could be a challenge if a full-frame model is in your future. There are lenses that are compatible with both kinds of DSLRs, but they cost plenty and don’t provide the fastest apertures, such as f/2.8.
In conclusion, the best strategy for deciding on a DSLR with a full-frame sensor is to watch the marketplace for further technological developments and lower prices before you buy.