HOW–TO

Digital Horizons: Digital Formats

Find the “right” format for you
By Rob Sheppard

This Article Features Photo Zoom

Advantages: A full-frame sensor allows use of a full range of focal lengths exactly as they were used with 35mm film. A specific wide-angle focal length, for example, acts exactly the same on a full-frame sensor as it does with film. This isn’t true with the APS-C format, where the angle of view of focal lengths is narrowed so that wide-angle lenses don’t act the same. A big advantage is that you can use faster, prime wide-angle lenses at their full 35mm angle of view. In addition, lenses give depth-of-field effects similar to 35mm film (which may or may not be an important criteria for an individual photographer). The full-frame sensor is also a very low-noise sensor. This usually is noticeable at higher ISO settings. And like the larger sensor, the full-frame sensor has the potential for capturing a wider range of color and tonalities compared to smaller formats.

Disadvantages: The size of a sensor definitely is still related to cost. Full-frame sensors cost more than smaller-frame sensors. In addition, like larger-format sensors, full-frame sensors require a bigger image circle compared to smaller formats. The result is that lenses tend to be larger and heavier for the same focal length. Also, compared to smaller formats, full frame requires longer focal lengths for the same in-frame subject size, resulting in a need to carry bigger teles for the same effects.

APS-C. The digital SLR really got its start with the APS-C-sized sensor, which gave a format smaller than 35mm at the size of APS-C film. This was done at first for cost reasons more than anything else. It simply was possible to create a sensor this size and be able to sell it at a price that photographers could afford. Yet this sensor wasn’t so small that the lenses for 35mm cameras wouldn’t be appropriate.

Advantages: The APS-C sensor still allows for less expensive cameras. It costs considerably less than a full-frame sensor. In addition, these smaller sensors see a smaller part of the image coming from a specific focal length. This gives more of a telephoto effect to any given lens, allowing a photographer to carry a smaller focal-length lens to gain a stronger telephoto effect. In addition, APS-C-format cameras can allow for a slightly smaller camera design compared to full-frame cameras, and they definitely allow for smaller lenses (because of the need for a smaller image circle). This can be a real advantage for the field photographer who wants to keep weight and gear size down.

Disadvantages: Sensor size still has an effect on noise. While the latest sensors and the technology built into cameras keep noise minimal at normal ISO settings, you typically see more noise at higher ISO settings with this smaller format. In addition, noise is more likely from an underexposed image that you had to brighten. The smaller sensor also sees less of the area covered by a given focal length, so the APS-C format has less selection in wide-angle focal lengths compared to full-frame cameras.

Four Thirds Format. The Four Thirds format was started as a way of creating a unique digital format that wasn’t limited by the challenges in making larger-format sensors. It was originally meant as an open format that wouldn’t have a proprietary lens mount, which would allow multiple manufacturers to use this format and its lenses. Sensors are smaller than APS-C, which makes this the smallest D-SLR camera format on the market. Originally, only Olympus made these cameras, but now Panasonic makes them as well.

Advantages: Size is probably the biggest advantage of the Four Thirds format. This sensor is so much smaller that lenses and cameras can be made considerably smaller as well. In addition, the sensor sees a much smaller angle of view through a given focal-length lens. The result is that you can get some hefty telephoto equivalence in much lighter and shorter lenses. This size can be a tremendous advantage for the field photographer who wants to reduce camera bag size and weight. Another advantage is that this format was designed specifically for digital, so all lenses also have been designed specifically for digital and to get the most out of the sensor size.

Disadvantages: The challenge for this small format has been to get a sensor with higher megapixels and low noise. However, there are high-quality sensors available in this format today, and at standard ISOs they give results similar to any other format. Still, as ISO increases or very underexposed pictures are brightened, noise always becomes much more obvious. The small size of the sensor might have been a problem for wide angles except that lenses have been designed specifically for this format. There isn’t a legacy set of lenses that have to be adapted to it, so wide-angles are quite available here.

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