DSLR Camera Lenses for Filmmaking
In the filmmaking world, camera lenses for your DSLR are very important. So choose your lens wisely. Without a good lens, you have nothing but a really cool, albeit expensive, paperweight.
While essential, lenses do more than capture an image or control focusing the scene; they’re also an important tool for creating composition and controlling perspective.
DSLR cameras use an interchangeable lens system that allows you to choose the best focal length for each situation. Focal length determines the magnification of the image. It’s judged on the following factors: optical quality, which dictates the sharpness; lens speed, which determines how much light comes into the lens; and focal length, which decides the actual magnification.
Once upon a time, focal length was easier to explain because all SLR cameras shared the 35 mm format, and therefore was consistent in image magnification.
When it comes to focal length, the actual magnification depends on the sensor format in your camera. Remember, all but the full-frame sensor are smaller than the 35 mm film frame, so the actual magnification of the same focal length differs in size.
Here’s the breakdown:
Normal lens: The age-old question of What is normal? applies here. This lens reproduces a field of view with a natural perspective, very much like our eyes. In mathematical terms, that’s about a 40-degree angle of view when you’re holding the camera horizontally.
In the 35 mm format, or full-frame sensor in digital-speak, that is equivalent to a 50 mm lens. When using a camera with an APS-C size sensor, that 50 mm lens behaves more like a moderate telephoto in the 80 mm range. Normal for this format includes a 28 mm lens, which renders the respective equivalent of a 45 mm lens.
Wide-angle lens: Any focal length that provides an angle of view greater than 60 degrees is considered a wide-angle lens. Of course, depending on the sensor size of your camera, the effects differ. That’s the biggest drawback with making movies with DSLR. The APS-C sensor makes your wide-angle lens behave more like a normal lens, and even those cool ultra wide-angles lens are merely wide angle.
Ultra wide-angle lens: The biggest misconception about ultra wide-angle lenses is that you use them to include more of the scene. Quite the contrary: These lenses are more suited to getting really close to the subject for either an abstract capture, or for dealing with a crowded situation like a red carpet.
Basically, an ultra wide-angle lens with a field of view 84 degrees, or around a 20 mm lens on a 35 mm camera, qualifies as an ultra wide-angle lens. But remember, the same lenses that used to provide an expansive, beautifully distorted view on a full-frame sensor act much less wide angle in the APS-C format.
Telephoto lens: A telephoto lens enlarges distant subjects. But more than that, it can manipulate subject distance by compressing the space between near and distant objects. The telephoto range begins with an angle of view less than 25 degrees, which is around 85 mm.
Zoom lenses: The most noticeable difference between a DSLR and a video camcorder lies in the zoom lens. DSLRs do not have a lens built in to its body with servo-power (motorized zooming) like a dedicated camcorder does. They cover a moderate wide angle to extreme telephoto range. Unfortunately, DSLR lenses generally cover a much narrower ratio, and certainly do not have powered functionality.
Even when on a full-frame DSLR, common lenses like an 18-55 mm zoom provide a slightly wide to telephoto view. In addition, when you use a lens with a greater range, you add excess weight, and often limit maximum aperture, making the camera less usable in low lighting. Of course, you usually have sharper optics, at least when compared to the consumer level.