Despite offering much larger-format sensors than those you find in a typical camcorder, the problem with using your primary still camera for video is that a number of accessories will be required to gain the same advantages that a dedicated camcorder system has right out of the box. Camcorder bodies include XLR connections for the use of balanced professional microphones, for example. While a number of mics are certainly available for DSLRs from companies like RØDE, Shure and MXL, they use a 3.5mm jack, which feeds a very small voltage. So they require AA batteries, and as these mics are unbalanced, they’re largely limited to the hot-shoe of a camera because of noise that will be created along longer cords.
Camcorders often have an affixed lens, as well, which provides not only a massive zoom that will cover most general situations nicely, but also autofocus that can be used silently during video capture. Most still cameras must be refocused manually during video takes, while others use autofocusing systems that create a lot of internal noise from the motors, which of course ruins the audio. (Available in the EOS 70D, Canon’s newer Dual-Pixel CMOS AF technology is hinting that still cameras will soon be able to mitigate this disadvantage, however, and manual focus is almost always used for major film cinematography anyway.)
Because many of these cameras scan in from the left to right, top to bottom, imaging artifacts like jelly motion, skew and moiré are far more pronounced in still cameras. Additionally, while the complex codec formulation of a still camera often results in exceptionally high imaging quality, the bit-rate fidelity in still cameras is actually lower than the bit rates you’ll find in a better camcorder. Historically, camcorder sensors are also divided into three-chip sensors where each primary color is split by a prism, so that color information can be captured without the debayering process. So while color is often very good in a still camera, and even perceptually the colors and contrast may look better, in reality, dedicated camcorders are far better for green- and blue-screen special-effects work. This design also increases sharpness, hence the crisper look to video when captured with a dedicated video camera.
Thankfully, there are a number of dedicated camcorder solutions that have attempted to bridge the advantages of large sensor systems with dedicated camcorder bodies that also sport the versatility of interchangeable-lens mounts. Because of the larger bodies and extra space for internal components, most of them address the many shortcomings of using a still camera for motion, offering versatile frame rates and uncompressed video files while highlighting the advantages of still cameras like extended light sensitivity and affordability.
Blackmagic Design has been turning heads with their line of dedicated, small form-factor camcorders, especially as several of the models offer your choice of Canon EF or Micro Four Thirds (MFT) mount, making them an ideal video solution for photographers already owning Canon, Olympus or Panasonic lenses. Currently, there are five models in the lineup: the Blackmagic URSA and Production Camera 4K, both with large Super 35-sized sensor and 4K capture, as well as the Blackmagic Studio Camera for broadcast and live events, the Pocket Cinema Camera and the Blackmagic Cinema camera. Additionally, with the small size of the MFT sensor, there are a litany of adapters available for using cinematic PL mount and virtually any other lens on models that offer an MFT mount: the Pocket, the Studio and the Cinema Camera.