Tuesday, December 18, 2012
Lenses For Still + Motion
Putting together the best optics for versatility and practicality
|This Article Features Photo Zoom|
CLOCKWISE FROM TOP: Red Scarlet, Canon EOS-1D C, Nikon D800
RED pioneered the professional 4K and 5K still and motion workflow with their DSMC (Digital Still & Motion Camera) concept. Other manufacturers have followed suit, and as still photography and motion capture merge for many professionals, lens choices are impacted. In particular, with motion capture, there are several additional considerations, such as how focal length, angle and lens choice will affect story, subject and mood. At the same time, for still photographers, resolution and imaging quality matter above all else. This is one of the reasons why RED offers their cameras with different mounts. Depending upon your emphasis—still or motion capture—you might find one line of lenses better-suited than another.
The last couple of years have also seen the introduction of a new class of large-sensor camcorders that offer the imaging quality of DSLRs and mounts for DSLR lenses to be able to cover these larger imaging circles. While it's true that current DSLRs excepting the Canon EOS-1D C only offer up to 1080p at a little more than 2 megapixels in resolution by each frame, 4K, and at 16 times the resolution of HD, even 8K video formats are on their way. What all of this means is that putting together a comprehensive set of lenses that will be able to future-proof high-resolution video projects while still providing enough versatility for stills is no simple matter.
Prime lenses are much more compact and they're lighter, which makes them ideal for use with low-profile, video-capable DSLRs, especially as many offer a much closer minimum focusing distance over zooms. One of the principal advantages of a DSLR over a traditional camcorder, after all, is the low-profile body construction for better scene placement. Primes are designed to cover a single focal length, and to do so efficiently, while zooms include several lens elements that also enhance light scatter and aberrations while reducing overall contrast and sharpness. But perhaps the primary advantage to using primes over zooms is that they force you to make a conscious decision on which lens to utilize previous to a shot. The flexibility of a zoom is certainly an advantage, but it also can lead to lazy compositions. Primes force you to think ahead as to what the most effective composition will be in terms of the storytelling process. This helps to firm an understanding of how focal length, angle and lens choice will affect story, subject and mood.
Primes also offer much better low-light capabilities, as well as imaging quality that surpasses a zoom in the intermediate apertures. This is important because the shutter speed and frame rate must stay the same when capturing video. The larger the aperture, the more leverage you'll have in low light, as well as normal light. In addition, the sweet spot of image quality starts a couple of stops from wide open or closed down whether using a zoom or a prime. This means that primes offer a better range of sharper apertures thanks to ƒ-stop ranges that routinely start at apertures larger than ƒ/2.0. An ƒ/1.4 prime, for example, would start to hit the sweet spot of sharpness at ƒ/2.8 or smaller, around two stops in, while a zoom with a base constant aperture of ƒ/4.0 wouldn't provide an optimal image until ƒ/8 or so. Despite the limited 2-megapixel resolution of each 1080p HD frame, sharpness and image quality will show in the video. Working with a prime set of lenses with matching apertures will also give you a swappable lens system that won't require changes to exposure every time you change the lens. This can save you considerable time if lighting a set or working with optical filters, which are seeing a resurgence in popularity thanks to video.
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