Camcorders: Beyond the boxing ring - TvTechnology

Camcorders: Beyond the boxing ring

It is absolutely vital that a good match is achieved between your camcorder and its lens. Decisions of tape format, and thus compression scheme, must
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It is absolutely vital that a good match is achieved between your camcorder and its lens.

Decisions of tape format, and thus compression scheme, must be left to your eyes and the judgement of your photographers.

The fights have been going on for years. Most people who've been around a while remember all too well the Beta vs. MII bout. In the last few years, we've seen the advent of a number of competing analog and digital tape formats — all with their proponents and sometimes-vociferous detractors. There are days when it seems that “Friday Night Fights” seems an appropriate way to describe the discussions over MPEG compression at the local SBE chapter meeting.

Let's look at three main points that most people seem to gravitate towards when looking at new camcorders. First we'll look at imager technology and some of the recent advances in chip design. Next, we'll focus on optics — the all-important step in getting the image to the imager. We'll finish up with a quick look at those pesky recording technologies, both tape and tapeless.

Heart of the camera—the chips

The key word on imaging chips is “improvement.” There has been a steady and impressive improvement in chip design over the last couple of years. Most manufacturers chalk this up to what they've learned in creating new HD imagers. The technology required to produce a cost-effective two million pixel imager on a 2/3" CCD chip is truly mind-boggling. The trickle-down effect of all that R & D is showing itself in the families of standard definition imagers coming out now.

Just about every manufacturer is offering IT and FIT imagers in both 1/2" and 2/3" chips. A couple of companies offer FT devices in 2/3" as well. The benefits of the aforementioned HD research, however, are that today it is possible to buy a very nice 2/3" FIT or FT chip camera for the price of a 1/2" IT a couple of years ago. With new DSP chips coming on the market, even the lower end IT cameras are making impressive pictures with much better smear control than was possible in even relatively recent designs.

One area in which the various mainline broadcast camera manufacturers differentiate their products is in how they use the imagers. For instance, cameras that can switch back and forth between 4:3 and 16:9 aspect ratio are common now. It is how easily that switchover is made and how the camera's optical system compensates for it that becomes the selling point.

Of course, it is still possible to buy a camera that uses a fixed aspect ratio CCD and outputs only that aspect. If you're looking at HD camcorders, then that CCD will be a 16:9 chip with between 1.5 million and two million pixels. In the world of standard definition, the fixed 4:3 chip is really at the height of its evolution right now. Low light capability, blue sensitivity, anti-smear and overall resolution has never been better.

Optical choices

One of the oldest maxims in photography is that with lenses, you always get what you pay for. In placing glass on the front of your camcorder, this has never been truer.

One of the big changes in recent years with lenses has been the mating of specific lenses with specific CCD chipsets. There was a time when it didn't really matter what you picked out for a lens, so long as it fit the front opening in the camera. Now, camera manufacturers and lens makers are working closely to optimize every part of the lens to squeeze every last drop of performance out of what has become a total optical system — lens, optical block, chipset and image processor.

The desire to have the switchable aspect camera has brought about a number of the recent changes in lens design. A camera maker must have a lens that will not crop or distort the image when the changeover is made between aspect ratios. Most lens makers accomplish this by inserting an aspect ratio diopter into the lens system. Similar in function to a 2X tele-convertor, the aspect diopter is rotated into place when the camera is operated in the 16:9 mode. The diopter ensures that the image falling on the CCD imager still contains the entire scene and doesn't crop areas out.

However, even cameras that are not switchable make use of lenses specific to the chipset involved. For HD camcorders, a larger objective element and higher light gathering capability are desirable, as are more accurate focus control and zoom-focus tracking. Even the basic non-switchable 4:3 camera may make use of a specially matched lens that is designed to mesh with that camera's DSP to achieve superior colorimetry, low light capability, and so on.

It is absolutely vital that a good match is achieved between your camcorder and its lens. Failing to work for this match, it is just as easy to buy a really awful $25,000 lens as it is to get a superior $18,000 lens. The good news is that the camera manufacturer will help with this, having lens-matching tables available for all the major lenses on the market.

The “corder” part of the camcorder

Tape or disk? Which tape? We aren't going to settle the tape fights here. We're going to assume that your company will choose a tape format based on some set of criteria that makes sense to the operation. Let's start by looking at portable disks.

Two manufacturers offer the ability to record direct to disk right now. The technology was introduced several years ago and has quietly been undergoing steady improvements even though it's seen a fairly slow adoption rate in the field. This may be due to a perception of recordable disk packs being fragile, unreliable, expensive and hard to work with. Users will tell you of the amazing ability to edit in the camera and come back to the newsroom with a nearly finished piece. They'll tell you about the ease of use and how after you get used to the idea of not having to mess with tape, you don't miss it. On the other hand, the companies that market disk-based cameras still market many, many more tape-based units. Tape-based camcorders are still significantly less expensive than comparable disk-based units, if you ignore the long-term costs of videotape purchased for each camcorder in your inventory.

The simple fact is that in most cases, it is far easier to get approval to purchase tape-based camcorders — especially given the current economic conditions throughout the broadcast industry. Reliability and predictability — nearly all the myriad tape formats have these two things in common. The modern videotape transport is simply a marvel. In case after case, speaking with user after user, the one thing that comes to the surface is the fact that you can very nearly abuse most major-name camcorders on the market and fully expect good, usable pictures to make it back to the newsroom or edit suite.

And in the 15th round?

Decisions of tape format, and thus compression scheme, must be left to your eyes and the judgement of your photographers. Obviously the finance people will weigh in as well. As we all know, each company performs the capital acquisition task in its own way. Perhaps you get your cameras shipped to you by the head office without discussion. Maybe you get what the GM says is most cost effective. There's even a chance that you'll hold a shootout and determine what's best for your operation based on seeing results. In the end, if you're like most of the rest of us, you'll strike that fine balance between the best technology that you can afford and what the photogs are willing to schlep around on their shoulders during a cold 10-hour day in the rain.

Edward E. Williams is director of engineering for KPDX Engineering, Portland, OR.