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Last Updated: Jul 2nd, 2008 - 21:15:22 |
High definition will inevitably become a widespread if not universal television broadcast format. However, it’s not yet clear when that will happen. So it’s also not yet clear when high definition camcorders will be routinely required for acquisition for non-fiction programmes. With that in mind, this E-zine aims to give some background to high definition technology and the Sony high definition camcorders currently available.
High Definition – Formats and Camcorders
Before venturing into the world of high definition, it should be said that our UK-based clients primarily use Digital Betacam and DV Cam camcorders and we find minimal demand for HD Cam. Our American clients are using HD Cam more frequently than our British clients but Beta-SP remains the format they most commonly request.
Two High Definition Formats
To begin with, the future of high definition broadcasting is unclear. There are two HD formats being considered for transmission. One is 720p (720 horizontal lines or rows of pixels in the image) and the other is 1080i (1080 horizontal lines or rows of pixels in the image). The “p” stands for progressive scan and the “i” stands for interlaced scan but more on this later. Panasonic manufactures the camcorders that generate 720 horizontal lines and Sony manufactures the camcorders that generate 1080 horizontal lines. The European Broadcasting Union (EBU) has suggested for discussion using 720p for public service broadcasters but say that does not mean they favour 720p as the standard HD format for transmission. Trade magazines say BSkyB plans to broadcast both 720p and 1080i in a service that will begin sometime in 2006 although I was recently told 1080i may be the only format they use for transmission.
The Sony 1080-line system has one clear advantage over Panasonic’s 720-line system. Each image contains more than two million pixels (1920 vertical lines x 1080 horizontal lines) compared to 900,000 pixels (1280 vertical lines x 720 horizontal lines) in an image from a Panasonic high definition camcorder. This gives a superior picture. The advantage of the 720-line system is it takes less transmission bandwidth to broadcast.
Now to the difference between “interlaced” and “progressive” scan. These terms refer to the way television images are processed for transmission.
Interlaced Scan
Standard definition television broadcast signals are processed by television sets in an “interlaced scan” format. This means the screen first scans the odd numbered horizontal image lines, or rows of pixels, sequentially from top to bottom (1, 3, 5, etc). It then returns to the top and scans the even numbered lines (2, 4, 6, etc). In summary, the full picture from top to bottom is first made with half the information there and half of it missing. Then the missing information is filled in. In the PAL standard, each of these two processes takes 1/50th of a second so the entire process takes 1/25th of a second.
Progressive Scan
“Progressive” scan differs from interlaced scan in that the image is displayed on a screen by scanning each line (or row of pixels) in a sequential order rather than an alternate order, as is done with interlaced scan. In other words, in progressive scan, the image lines are scanned in numerical order (1,2,3) down the screen from top to bottom, instead of in an alternate order (lines or rows 1,3,5, etc... followed by lines or rows 2,4,6). By progressively scanning the image onto a screen every 25th of a second rather than "interlacing" alternate lines every 50th of a second, a smoother, more detailed, image can be produced on the screen that is perfectly suited for viewing fine details and is also less susceptible to interlace flicker.
The Sony range of camcorders offer both interlaced and progressive scan functions in a range of settings.
Procam Television and High Definition Camcorders
As a facilities company, we are moving into the HD Cam market – but cautiously. We have Sony models but have not purchased any Panasonic products. This is only in response to what our clients have requested most. Below is a summary of each model and what it offers from the lowest to the highest priced model.
Sony HVR-Z1P
This is one high definition camcorder we can recommend using immediately without exception. We purchased 15 of them in February of this year. It is an upgrade of the DSR-PD170P compact camcorder. The main reason for the unqualified recommendation is that the camera has a 16:9 chip so it shoots true wide screen images. It also delivers superior pictures.
Sony HDW-730S High Definition camcorder
The 730S is geared towards mainstream television programming rather than film or high end television drama productions. It shoots using the interlaced function only and can be switched between 50i and 59.94i. Progressive scan is not possible with the 730S. But if you don’t need to use progressive scan and you’re shooting for television, this camcorder produces excellent images and it allows you to shoot HD Cam on close to a standard definition budget.
Sony HDW-750P High Definition Camcorder
The HDW-750P offers the choice of shooting 25 frames per second in progressive scan mode (25P) to give your pictures a film look or of shooting 50 fields per second interlaced (50i) to conform to the PAL broadcasting standard. The camcorder has a 2.2 million-pixel FIT CCD, which is a step up from the IT CCD in the 730S, and Advanced Digital Signal Processing (ADSP).
Sony HDW-F900 Multi-format Cine Alta High Definition camcorder
This is the top of Sony’s high definition (1080 lines x 1920 pixels) camcorder range. The F900 offers the ability to shoot in any setting you might want. In progressive scan, it can shoot 23.98, 24, 25, 29.94 or 30 frames per second. In interlaced, it can shoot 50, 59.94 or 60Hz. This means you can shoot for any standard anywhere in the world. If you are shooting for cinema release, the F900 is the only Sony camcorder that can shoot 24P (24 frames per second film standard).
Panasonic AJ-HDC27
The Panasonic range includes the AJ-HDC27 VariCam. This is a DVCPRO HD camcorder that offers variable frame rates which can be set from 4-fps to 60-fps in single frame increments at the touch of a button. The question we have about Panasonic high definition camcorders is does going from the 625 lines offered by current PAL standard definition cameras to the 720 lines offered by Panasonic’s high definition format really merit the investment required in acquisition and post production equipment? It’s something to consider.
Thank you for reading this and please visit our web site www.procamtv.com to find out how we can meet you production kit and crewing needs.
About The Author
Cal Barton began working in television for the Canadian Broadcasting Corporation in Vancouver in 1982. His background includes directing coverage of major international news stories, directing documentaries and directing and vision mixing for multi-camera shoots.
cal@procamtv.com
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