“HD” vs “HDV” - What makes your footage one or the other?
October 10th, 2007 : John Kary
So the Canon HV20 does 1080p for $900. So why not shoot the next Star Wars: Episode II (1080/24p on a Sony F900) with it? Because of the common misconception between “HDV” and “HD” resolution.
I was reading a thread over at TapersSection discussing the Canon HV20, and a user there was very quick to remind everyone that just because you see the golden number 1080p, doesn’t mean you will have a great image. Here is my response to the post, plus a bit extra, which tackles the issues of HD vs HDV and the problems facing a production when choosing which camera to shoot on.
From what I’ve read second-hand by people like Stu Maschwitz, the HV20 has a lot of little quirks about it that make it a bit more demanding than working with a camera with more intentional features like a DVX or HVX. Things you will run into like the rolling shutter, CMOS artifacts, and using the camera’s photo-button to check exposure make the $900 a bit of a struggle compared to more expensive cameras.The HV20 shoots to 4:2:0 long GOP MPEG2 HDV at 1440×1080/24p. I think what wilsonedits is getting at is that the camera is not “true HD” because it doesn’t pump out and record 1920×1080 native off its image sensor. Where this all morphs into a discrepancy is when talking “HD” vs “HDV” resolutions.One person might argue that anything above above Standard-Definition NTSC resolution of 720×480 is considered HD (excluding PAL’s extended vertical resolution of 720×576, of course.) Then again, another might say that anything that isn’t 1920×1080 isn’t even “HD.” Then what about all of these cameras and TV’s that do 720p? 1080i? 1080p? It’s easy to get confused. Let’s lay out a few resolutions of HD/HDV, disregarding their different frame-rate capabilities:
- Sony CineAlta/F900 (MSRP $102000) - 1080 @ 1920×1080 1:1
- Panasonic VariCam (MSRP $45000) - 720 @ 1280×720
- Panasonic HVX200 (MSRP $5995) - 1080 @ 1280×1080, 720 @ 960×720
- Sony Z1U (MSRP $5946) - 1080 @ 1440×1080
- Canon HV20 (MSRP $1099) - 1080 @ 1440×1080
You might see, “oh, the HVX200 has better horizontal resolution than the VariCam, so at $6000 it’s a total steal!” Yet there’s much more to producing a good image than strictly resolution. Differing features, like the recording medium (including color fidelity due to color sampling for compressed storage), codec, frame-rate options, lens-mounts (or lack there of), workflow… the list goes on and on. The decision on what camera to use often times doesn’t rely solely on resolution, and might include:
1. How much you can afford. Either to buy, or to rent.
2. What workflow options you have available (again, dependent on money or software competency)
3. What quality you need the deliver the final product at (a huge movie theater screen, or broadcast television)
Many HDV cameras that shoot to MiniDV throw out a lot of information to be able to fit the image onto tape. This all falls back to chroma subsampling, or how often and to what extent the color of each pixel is measured before being compressed to tape (and if you really want to geek-out on the subject, check out a 2005 American Cinematographer article on color spaces.) Because many small-format cameras don’t have any way to store massive amounts of color and resolution data, they are limited in the quality of pictures they produce.
Different cameras do this in different ways. Some use different compression codecs, while others store the image at a slightly altered resolution, then require the editor to adjust the size of the pixels (pixel-aspect ratio) in the NLE to make the footage “look like” it’s at 1920 pixels wide, when really it’s not. Which camera you shoot on deems which aspect of quality you will be giving up.
So where do you draw the line between “HD” and “HDV”? The marketing hype engine of capitalism leads people to believe that a resolution greater than standard-def is “HD,” while the method you capture and store your footage from the camera might be what gets it labeled as as “HDV” or “HD.”
I will argue that unless it’s 1920×1080 at 1:1 full raster, it’s not HD, and is rather “HDV.” But at the same time, this doesn’t mean HDV doesn’t have it’s place in when and where it could and should used.
Categories: Tech Corner, Tutorials
Hi,
Good info, but you forgot one major thing differenciating a 1000$ camcorder from a 100.000$ one : the size of the sensor.
While a 1000$ camera will have a 1/4″ (which in fact is even less than this), a middle range will have a 1/3″ and a pro will have a 2/3″, or a plain 35mm frame (Genesis, Red5…).
So what ?
The size of the chip will have an impact on the light that can come to the sensor, which is also called the sensitivity (or dynamic range, which is related but not really the same thing).
It will also change the aperture and depth of field. A larger chip will be closer to a 35mm look, which is what people are used to call “good quality picture”.
finaly, don’t forget that the best camera, with the biggest resolution, does not do the movie. The operator, the DP, the DIT, and you team do !
Do HDV cameras produce Strobes when Panning or Tilting is done?
It depends on the type of image sensor used inside of the camera. If the censors are CCD, like most older tape-based cameras, then no. If the censors are CMOS, like most newer cameras, then yes.
This effect is called the “Rolling Shutter” I talked about in the article above. You can read more about it here: http://dvxuser.com/jason/CMOS-CCD/