Monday, April 28, 2008
Fast Lenses On Sub-Full-Frame Sensors
Quick, inexpensive and light, sub-full-frame lenses aren't just for the amateur market anymore
While full-frame D-SLRs offer the highest in professional quality, often what really matters is pure, unadulterated speed. In the realm of full-frame vs. sub-full-frame lenses, fast, compact and superb image quality is the precedence from which lenses are judged. But when pro levels of speed and quality are avail-able at sub-full-frame costs, it might be time to take a look at the offerings.
The majority of D-SLRs on the market have a sensor that's smaller than the film plane of traditional 35mm-film (36x24mm) cameras. Known as sub-full-frame sensors, they are available at price points far below the cost of your Canon EOS-1D Mark III or Hasselblad H3DII. The advantage to a sub-full-frame sensor, from a manufacturer's point of view, is that they save on time and cost for development and construction when tailoring a lens to a smaller image sensor.
On the other hand, one of the difficulties with sub-full-frame sensors is that there are a smattering of individual sizes and formats. Manufacturers spend a lot of time and money developing sensors that work best with their own system. Canon, for instance, has two competing sizes within its own line of cameras, APS-H at 28.7x19mm, and APS-C at 22.2x14.8mm. Olympus developed its Four Thirds System at 17.3x13mm, Nikon's APS-C-sized sensor size is 23.6x15.7mm, Sigma is 20.7x13.8mm, Sony uses a 28.0×22.3mm APS-C and so on.
To top it all off, any confusion caused by varying sensor sizes is minimal when compared to the amount of lenses available. From fixed-focal lengths (primes) to wide-angle to telephoto, the only constant is that each lens has its own individual construction, utilizing unique combinations of glass, material and chemical cocktails.
The dizzying complexity to lens design has been streamlined a lot because of, and thanks to, the digital revolution. So while the construction of a lens is certainly more advanced, the goals have always remained the same—sharp images from a lens with a fast and constant aperture.
The importance of a fast lens for a traveling photographer looking to cut down on some extra weight can't be overstated. Fast-aperture lenses made specifically for APS-sized camera sensors offer exceptional low-light performance and speed for photographers. Here are some choices from the manufacturers themselves on which lens they carry with them on the road.