Basic Tech: HD Video And Autofocus
DSLRs with HD video are the wave of the future. Is lagging autofocus a thing of the past?
If, the first time you picked up an HD video-enabled DSLR, you blasted full-speed ahead into figuring out how to shoot video without reading the owner’s manual (as I did), you were undoubtedly surprised to discover how poorly your camera focused (as I was). There’s a misconception that DSLRs can’t autofocus when capturing video. In fact, the cameras do have autofocus built in. It just sometimes pales in comparison to the fast and accurate autofocus some of these DSLRs utilize when capturing stills.
Even inexpensive camcorders autofocus, while many of the relatively expensive HD-capable DSLRs don’t. So what’s the deal? Well, let’s get one thing clear: DSLRs with video aren’t intended to replace camcorders. And while professional videographers tend to focus and adjust exposure manually, the ability to autofocus is crucial for many photographers.
When users got their hands on the first DSLRs with HD capabilities—the Canon EOS 5D Mark II and the Nikon D90—the less-than-exciting video AF capabilities were a letdown, especially compared to the awesome continuous autofocus these cameras have when shooting stills. Photographers had to give up highly evolved autofocus to focus manually or to use autofocus before recording began. But why?
A DSLR with an optical viewfinder also has a mirror inside the camera serving both the photographer’s eye and the camera’s autofocus. The mirror simultaneously reflects light into a very fast and accurate phase-detection autofocus system housed in the mirror box. When a still exposure is made, the viewing mirror flips up and out of the way, allowing light to travel through the shutter to the image sensor. Camcorders don’t have mirrors, however. They use contrast-detection autofocus that’s able to read right off the sensor. It works, but contrast detection can be slow and inaccurate compared to phase detection—particularly in low light.
In DSLRs, live-view technology paved the way for video recording and auto-focus. The ability to send a video signal from the sensor to the LCD also makes it possible to see what the sensor sees even while the mirror is up—in a still camera’s Live View mode or during HD video recording. In live-view still shooting, autofocus already relies on the more rudimentary contrast-detection approach. This camcorder-style autofocus also takes over during video recording.
Some cameras, such as some Micro Four Thirds models from Olympus and Panasonic, never had mirrors in the first place. These cameras have utilized increasingly fast and accurate contrast-detection autofocus to compete with larger viewfinder-sporting, phase-detection autofocus DSLRs. Consequently, these cameras added HD video capabilities and found themselves already well prepared to autofocus during recording.
Compared to the earliest HD video DSLRs (from about a year ago), autofocus during video recording is improving by leaps and bounds. Many cameras already incorporate specialized autofocus features into video recording.
There’s an additional focusing consideration for photographers capturing video with any digital camera, and that’s how it affects audio recording. Using the camera’s internal microphone, every focus noise is amplified, making the silence of a quiet autofocus motor even more important. Professional video lenses have long been quiet, and this trend is likely to continue as DSLRs become hybrid cameras. Until the lenses are absolutely silent, prefocusing and subtle manual focus adjustments still have a place.
K.Panduranga Reddy makes this comment
Wednesday, 23 December 2009
digital HD camera
Isaw the article fromconsumers guid,they said that is not a true HD vedio.Is that true.Which one is the True HD digital camera.Douglas McClung makes this comment
Friday, 15 January 2010
just can't do one thing good
I'm sick of having to dig through equipment designed to do a dozen thing half ass-ed to find the one that does one thing beyond belief.UM makes this comment
Saturday, 13 February 2010
Make what it does better
I agree with Doug. Instead of new, half-baked features, perfect the features that my DSLR has. Why the 1d Mark IV was ever given video is escapes me. Spend the time, and R&D money, on making things like the autofocus better. I think Canon added video (a largely ignored feature by most who use the camera) to help justify the huge price jump. If I want to shoot video, I will buy a video camera, a good one, not a DSLR!Mike B makes this comment
Tuesday, 16 February 2010
Unwanted features
I agree with the above comments. The manufacturers should stop trying to add new features to every new DSLR and spend their time perfecting the important functions like autofocus and low light sensitivity. While they are at it, they can make the files write to the memory card faster. Please stop adding junk I am not going to use!!! This is especially true for professional or "prosumer" cameras. I can afford to buy a real video camera if I need one and computer software to create special effects if I want to. Arghhh!!!Tim makes this comment
Tuesday, 11 May 2010
Seriously?
You guys are complaining about Canon and others adding video and not making their cameras better? Look at the difference between the 5D and the 5D MKII. There is a huge jump in resolution and a serious bump to the ISO performance. Those two things implemented at the same time are very difficult to do and the fact that Canon did a good job at it is proof that they are taking image quality serious and not just adding gimmicks to sell cameras. All this without a jump in price either. These video capable SLR's are improved over their predecessors significantly without the video. The truth is that someone was going to add video so they all have to have it to stay competitive. Look at Sony, they haven't "lowered" themselves to adding video and their photographers are complaining about that. Also, the focusing issues of the 1D MKIII and MKIV are not issues that any of you hobbiest will ever be able to exploit. If you find another cheaper camera that can focus as good as either of these two you better buy it.ocwildlife makes this comment
Wednesday, 19 May 2010
HD video canon
Although I have had some good experiences, clarity is one, with the video feature on my 7D, my back up camera to the MKIII, here are the problems I've observed: Using heavy gear for wildlife photography and then having to exchange back and forth to tripods for stability is a real pain. Bring two sturdy tripods is just adding yet more heavy loads to carry. Better to have a medium weight video camera ready, no switiching back and forth. Its just too time consuming for on the spot shots requiring extemely fast focus in debatable light. I've decided you can rarely do both, and must decide which I want to do that day.ike f14 and slow the shutterspeed, which is the answer for a larger depth of field so less OOF work, but then you lose the bokeh. Yes, for the price of a lens I can do this with a video camera, and get better results. For shorter size lenses/wider, or stationary subjects, the dslr may be an ok video situation by itself, on one tripod. Bokeh is great.ocwildlife makes this comment
Wednesday, 19 May 2010
focus ability
I didn't have room on the last post, but to finish the autofocus problem, it does hesitate, so forget Birds in flight, wildlife ok, if it's kind enough to stick around for you. Using f14 for a lerger focal area helps, but this is not inteneded for fast moving targets, except for maybe at a finihs line race, surfing, maybe. I autofocus first, then switch over to Movie for a faster start. But refocusing is not that great in Manual. And if you shoot in Av or P, you will see very high ISO's which is really stupid if focusing at 1/160sec suffices for movement. You do not need high ISOs! Control that in Manual, but still autofocus problems.