#Four thirds system lens wiki manual#
Such mechanical adapter rings typically require manual setting of focus and aperture.
Corresponding lenses become larger, heavier and more expensive when designed for larger sensor formats. In particular, the Four-Thirds system allows the development of compact, large aperture lenses. The smaller sensor size makes possible smaller and lighter camera bodies and lenses.
#Four thirds system lens wiki series#
The E-4XX series was advertised as the smallest true DSLR in the world. He also pointed out the similarities between 4:3 and the standard printing size of 8×10 as well as medium format 6×4.5 and 6×7 cameras, thus helping explain Olympus' rationale on choosing 4:3 rather than 3:2.Īdvantages, disadvantages and other considerations AdvantagesĪn Olympus E-420 camera, sold with a very thin 25mm "pancake" lens. In an interview John Knaur, a Senior Product Manager at Olympus, stated that "The FourThirds refers to both the size of the imager and the aspect ratio of the sensor". For example, many lenses designed by Olympus for the Four Thirds System contain internal rectangular baffles or permanently mounted "petal" lens hoods that optimise their operation for the 4:3 aspect ratio. Sensor aspect ratio influences lens design. For instance, the Panasonic GH1 uses a multi-aspect sensor designed to maximize use of the image circle at 4:3, 3:2, and 16:9 each ratio having a diagonal of 22.5 mm. However, the standard only specifies the sensor diagonal, thus Four Thirds cameras using the standard 3:2 aspect ratio would be possible notably newer Panasonic Micro Four Thirds models even offer shooting at multiple aspect ratios while maintaining the same image diagonal. The emphasis on the 4:3 image aspect ratio sets Four Thirds apart from other DSLR systems, which usually adhere to the 3:2 aspect ratio of the traditional 35mm format. Incidentally, the imaging area of a Four Thirds sensor is almost identical to that of 110 film. The sensor's area is about 30–40% smaller than APS-C sensors used in most other DSLRs, but still around 9 times larger than the 1/2.5" sensors typically used in compact digital cameras. The usual size of the sensor is 18 mm × 13.5 mm (22.5 mm diagonal), with an imaging area of 17.3 mm × 13.0 mm (21.63 mm diagonal). Sizes of the sensors used in most current digital cameras relative to a standard 35mm frame The image sensor format, between those of larger SLRs and smaller point-and-shoot compact digital cameras, yields intermediate levels of cost, performance, and convenience. Thus, the Four Thirds System has crop factor (focal length multiplier) of about 2, and while this enables longer focal length for greater magnification, it does not necessarily aid the manufacture of wide angle lenses. For example, a Four Thirds lens with a 300 mm focal length would cover about the same angle of view as a 600 mm focal length lens for the 35 mm film standard, and is correspondingly more compact. The size of the sensor is significantly smaller than for most DSLRs and this implies that lenses, especially telephoto lenses, can be smaller. Lens design has been tailored to the requirements of digital sensors, most notably through telecentric designs.
Many lenses are extensively computerised, to the point that Olympus offers firmware updates for many of them. Unlike older single-lens reflex (SLR) systems, Four Thirds was designed from the start to be entirely digital. Proponents describe it as an open standard, but companies may use it only under a non-disclosure agreement. Patent 6,910,814 seems to cover the standard. The system provides a standard that, with digital cameras and lenses available from multiple manufacturers, allows for the interchange of lenses and bodies from different manufacturers. The Four Thirds System is a standard created by Olympus and Eastman Kodak for digital single-lens reflex camera (DSLR) and mirrorless camera design and development.
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