08-30-2017 11:06 AM
08-30-2017 12:00 PM
The reason the 60D doesn't have continuous auto-focus during video has to do with how the focus systems work.
What you *want* is a Canon camera that has Canon's "Dual-Pixal CMOS AF" system. ...and probably what you want is the 70D.
For normal photography with your 60D (through the viewfinder) the camera has a mirror that bounces some light into phase-detect auto-focus sensors (located on the floor of the camera below the reflex mirror). Light goes through a beam-splitter (prism) which will reconverge in-phase IF the focus is accuarate at that point. If the focus is not accurate then the light will be out-of-phase and the phase difference will indicate to the camera if focus is too close, too far, and by precisely how much. When you shoot, the camera samples the focus, finds the phase difference, and orders the lens to make the perfect adjustment and it will nail the focus. Sounds great, right?
All this falls apart when you go to live-view or video. Those focus sensors are on the floor of the camera. The focus has to occur when the reflex mirror is down. When you do video, the reflex mirror swings up and clear of the light path. Now there's no way to send light to the focus sensor. So the camera goes to plan B: use of "contrast detection" auto-focus.
The easiest way I know of to describe contrast-detection is to imagine taking a photo of a barcode. Black stripes on a white background.
If the barcode is in tack-sharp focus, then you'll have nice crisp black stripes (represented by lots of black pixels) and a white background (lots of white pixels). The edges of the barcode will have a very rapid transition from all-black pixels to all-white pixels... you wont have gray pixels.
But now suppose the barcode is out of focus... the bars are fuzzy. This would mean that if you inspect the pixels closely, you'd have lots of pixels that are variations of gray where the edges of the stripes should be... black pixels next to very dark gray pixels, next to medium gray pixels, next to light gray pixels... and eventually white pixels. That slow transition from black to white represents a gradual contrast change from pixel to pixel... rather than the rapid contrast change when the image is in tack-sharp focus.
Unfortunately all the camera knows when the contrast is poor is that it probably needs to adjust focus... but it doesn't know if it should adjust closer, farther, or by how much. So it needs to shift focus and take lots of samples to work that out.
So the camera tests focus and looks for edges of contrast and tries to detect how rapid the contrast change is occuring... then shifts focus and tries again... and it "guesses" it's way in to optimal focus. It takes a bit longer AND if you were recording video you would see this "hunt" for accurate focus (and it would be annoying).
You can force your 60D to re-focus during video (but you will see focus hunt) by pressing the astrisk button (*) on the back of the camera during video.
Enter Canon's "Dual-Pixel CMOS AF":
This new system changes the photosites that cover the sensor so that there are two pixels for photo-site instead of one. Each is behind a microlens that acts like a beam-splitter seperating the phase of light. If the image is out of focus then the data from the two pixels will be out of phase... but just like the original phase-detection system, the camera can determine if focus is either too close, too far, and by exactly how much. This allows the camera to order the lens to move back to accurate focus.
Since this is built into the imaging sensor ... the system can do this in live-view or video mode with the reflex mirror raised. It does need to use the phase-detect focus sensors located on the floor of the camera.
This gives you impressive focus tracking for moving subjects during live-view video with no focus-hunt.
The first of the mid-range cameras to get this feature was the 70D (the 60D doesn't have it). But now it's available in lots of cameras including the 1DX II, the 5D IV, the 7D II, the 6D II, the 80D (which replaces the 70D) and even the Rebel T7i has it.
So which camera is right for you is up to you... but you want to make sure the camera has the "Dual-Pixel CMOS AF" feature for the best continuous auto-focus even during live view.
Since you want the camera for vlogging, you might always an articulated LCD display (like the 60D has) so you can swing the diplay around to where you can see yourself while recording. The cameras that include that are the 70D and 80D as well as the 6D II.
But since you also mentioned you want to keep the price under $1k, you'd probably want to look at the 70D. The 80D is the newer model, but it's over the $1k price (for body only). These cameras will uses the same lenses as your 60D so you could use your exsiting lenses.
But while on the topic of lenses, Canon's newer "STM" lenses (stepper motor technology) are so extremely quiet when focusing that the internal microphone struggles to detect the sound from those motors.
08-30-2017 03:34 PM
The selection seems pretty limited at the moment, but you might keep an eye on the Canon Refurbished website. A dedicated video camera might make more sense than a still camera that also shoots video. Several of these seem to have external microphone jacks and would appear to be easily handheld. And they would be well below $1000, even at new prices.