You might want to look at the new 70D. It's not shipping yet, but for video it's got some very compelling features.
Previously, to get snappy/fast auto-focus, the camera had to do phase-detection auto-focus using sensors mounted in the floor of the camera's sensor body (note that auto-focus sensors are NOT on the sensor.) That only worked if the reflex mirror was in the "down" positition which is the normal position when taking still photos. If doing video, the reflex mirror has to be in the "up" position -- meaning it cannot bounce light in the phase-detect sensors.
This meant the camera had to focus using "contrast detection" -- and the best way to visualize that is to think of a barcode - black stripes on a white background. If you think about this, if the barcode is perfectly focused, then every pixel in your image should either be "black" or "white" only... you wouldn't have any "gray" pixels. If the image is out of focus, then you'd have lots of various shades of gray near the edge of any barcode stripe where it transitions from white to black. By adjusting focus until the contrast between two adjacent pixels is as high as possible, you know you've focused that location as well as can be done.
The problem with "contrast detection" is that it's slow (it is, however, very accurate.) This is the reason point & shoot camera owners complain about "shutter lag" (it's not really shutter lag... it's focus lag.) They press the shutter to capture a shot and the camera has to think about it for a half a second before it will take the image and that moment you were trying to capture is missed in that amount of time.
Enter the 70D... it has "Dual Pixel CMOS AF". Basically what this means is Canon engineers found a way to create microprism which give the camera the same split-prism focusing normally used in phase-detection AF (the really fast focus system) except... it's actually ON THE SENSOR. That means this camera has extremely fast auto-focus in video mode. It's probably as close to a camcorder experience as you can possibly get while using a DSLR camera... except you have the array of lenses to choose from and many of these can provide a much better quality than you could get from a camcorder.
Canon has several new lenses with "STM" motors (you'll see "STM" in the lens name). These use Canon's new stepper motor technology. While it is a very fast motor... the advantage in video is that the motor is virtually silent. The motor cannot be heard by the camera's internal microphone when recording. You probably wont want to use the built-in mic... look at a Rode VideoMic series (e.g. VideoMic, VideoMic Pro, Stereo VideoMic, or Stereo VideoMic Pro). The mics have a mounting mechanism that slides into the camera's flash hot-shoe (no metal contacts... it's just using that as a mounting point -- not using it to communicate with the camera.)
The EF-S 18-135mm f/3.5-5.6 IS STM would be a good first lens because of it's versatile range (and a noticeable improvement in both build and image quality over the original 18-135 non-STM lens.) If you want a shallow depth of field to create a deliberately blurred background look for a prime (a prime is a lens that does not 'zoom') with a low focal ratio of f/2.8 or lower (e.g. f/2, f/1.4). Keep in mind that the camera will have fairly "normal" angle of view at around 31mm (give or take... so a 28mm lens or a 35mm would look fairly "normal" -- neither wide-angle nor telephoto at that focal length. This makes it fairly versatile because if the human eye can see it without needing to squint or look around to take in the scene, then the camera can see it without needing to zoom in or out.)
Tim Campbell
5D III, 5D IV, 60Da
