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Choosing a Camcorder to Film Tennis Strokes
The choice of which camcorder to purchase or rent to film your strokes can be a difficult one. This section will be different from some of the others because here I will try to explain, in layman’s terms, some of the features of modern camcorders you may see advertised and how those features might relate to filming tennis strokes. Doubtless most of what I write here has been covered before in magazines such as DV Magazine, etc, but I wanted to be safe and write my own article to try and explain things as clearly as possible. In those magazines, many of those articles also recommend a particular camcorder or award an “Editor’s Choice.” I specifically want to avoid that here. My purpose is to guide and to explain, not to recommend. Armed with information, you can make your own decision. For discussion on which specific camcorder to purchase for filming your strokes, I recommend you check out the forums.
Also, I specifically want to mention that in this article I will not discuss the price of certain camcorder features, other than to possibly say that one feature may cost more than another. The reasons for this are twofold: First, prices are always changing, and what is expensive today may not be expensive tomorrow. Secondly, to some people, price is not the issue; having the right camcorder for the job is.
Finally, keep in mind that even if you purchase a camcorder for the purpose of filming yourself you will likely use it for many other things, and the right camcorder can last you many years.
Recording Medium
All camcorders take a video and record that video to some kind of storage medium. The type of recording medium that the camera uses is one of its primary distinguishing features. Many camcorders record to a small tape, others record to a DVD, etc. I will describe and compare the different recording medium options here.
MiniDV
MiniDV stands for Miniature Digital Video tape. This tape is a different kind of tape from DV tape or 8MM tape. As of February 2008, MiniDV can still be called the de facto standard for consumer camcorders, but other technologies are beginning to take over.
The tapes themselves are relatively small and inexpensive and can hold a good amount of footage. All MiniDV tapes hold the same amount of information. If you use the standard quality settings on a digital video camcorder (referred to as SP mode), a MiniDV tape will hold 1 hour of footage. If you use lower quality settings on your camcorder that same MiniDV tape can now hold 2 hours of footage (called LP mode).
Once you fill up the tape with footage, you eject the tape from the camcorder and put a new tape in. Or, you can rewind the tape and write new footage overtop of the old footage, just like reusing an old VHS tape to record TV shows. There is a limit to the number of times you can rewrite onto the same tape before you start to get errors happening in the footage. It’s about five times (to be safe).
MiniDV has its advantages and disadvantages. The advantage is that tapes are pretty cheap (they cost about 5 dollars per tape retail). They are “tried and true;” they’ve been around for years, and it is the technology that most Digital Video professionals use. The tapes are easily labeled, organized and stored. The disadvantage is that it is like any other tape-based technology: you have to fast forward and rewind the tape itself to see what is on the tape, the tape can jam, wear out, etc. It is inherently a mechanical technology. Finally, in order to play back your footage on a television, you have to hook the camcorder to your TV via some cables, and use the camcorder as the “VCR.” Some camcorders come with remote controls so you can sit back on the couch and control the playback; others don’t.
I also lastly want to point out that even though the MiniDV format is a tape technology, it is digital, NOT analogue. This is not like cassette tapes versus Compact Discs, where cassettes were analog and CDs were digital. The information on a MiniDV tape is recorded and played back digitally, preserving the quality and making editing much simpler.
DVD
DVD-based camcorders came to the market shortly after DVD technology appeared. The DVDs that the camcorders record to are not full-sized DVDs like you would buy or rent to watch a movie; they are about half the size, and store less then half the information. This makes them physically small enough to make them usable as a recording medium for a camcorder. They also hold about an hour of footage per disc.
DVD-based camcorders have some advantages over MiniDV tape camcorders. The footage is of course recorded directly onto a DVD, which can then be taken out of the camcorder and placed directly into a home DVD player or a computer DVD drive and watched immediately. The “seek” time for finding clips you want to watch is drastically reduced. You can skip from clip to clip just like you can skip tracks on an audio CD, you don’t have to fast forward or rewind a tape. It is also relatively easy to archive and store the footage. Just like tapes, once you fill up a DVD disc with your video footage, you can just pop in a new DVD and record more. Or you can go back and rewrite over what you previously recorded. As with tapes, there’s a safe limit to the number of rewrites past which you will start to see errors appear.
DVDs suffer some of the same problems as MiniDV camcorders. Just like a CD player doesn’t work well for joggers listening to music because the CD can “skip” due to shock and vibration, this can happen to DVD-based camcorders as well. Except the “skipping” happens as the footage is being recorded, not played back. Although the DVDs themselves are pretty hardy and resistant, they can still be scratched and ruined just like audio CDs, so you have to take care to make sure you store them properly.
Finally, although I mentioned above that it was easy to just pop your DVDs into a home DVD player to watch your footage on your TV, it can be a little more difficult than that. Some cheaper (sub-$100) home DVD players have trouble reading discs created inside DVD-based camcorders. If this fails, you can still use your camcorder as the “VCR” by leaving the disc inside the camcorder and hooking your camcorder to your TV using the cables that come in the box.
Hard Drive
Hard drive camcorders are a leap forward in many ways from MiniDV and DVD-based camcorders. Inside these camcorders is a small hard drive, which is a stack of spinning magnetic disks just like the hard drive inside your PC. The hard drives are usually isolated from vibration by rubberized mountings and other nifty gadgets that prevent any kind of “skipping” and write errors. The amount of footage you can store on these camcorders is only limited by the capacity of the hard drive. The standard entry-level capacity of these hard drives is about 20 to 30 gigabytes (GB). Most of these camcorders will store many hours of footage (at least 30+ hours).
Once you record clips to the hard drive, “seek” times to go find a clip and watch it are non-existent. Seeking, fast forwarding, rewinding are all instantaneous. Hard drives also make it possible to do significantly more in-camera editing than was previously possible with tape or DVD technologies. Essentially, you can make a good-quality “rough cut” of your movies right inside the camcorder before you transfer the footage to a computer for more intensive editing. Transferring the footage to the computer is also theoretically very fast, since it is not limited by the playback speed of a tape or DVD.
The disadvantages of hard drive camcorders are self-evident. The hard drive is not removable / swappable, so once you fill up the drive with footage you have shot, there’s no more room for new footage until you delete some of the old. With a hard drive camcorder, you are expected to transfer your footage to your computer for more permanent storage there. But what if your computer’s hard drive fails and you’ve already written over the footage on your camcorder? Bye-bye footage! There’s no original tape or DVD somewhere in a filing cabinet to fall back to unless at some point you transfer the footage to your computer, edit it, and then burn it back onto a DVD for archiving/storage.
For some people, this will not be a big deal. Just remember to always, always back up your footage that’s important to you.
Flash Memory
Flash memory camcorders use a memory chip to store the footage instead of a tape, disc or hard drive. The chips are similar to those used in digital cameras, except that instead of recording pictures, these record movies. The capacity of the camcorder to store footage is limited only by the memory capacity of the chips. Usually, these chips are hardwired into the camcorder, and cannot be replaced with higher-capacity chips.
Unlike all the technologies previously mentioned, these flash memory chips are essentially completely impervious to the environment. They are immune to shock, dust, vibration, mechanical failure, jamming, etc. Seek times are non-existent as with a hard-drive camcorder, and significant in-camera editing is possible. Transferring your footage to a PC is also theoretically very quick. This capacity may be limited by your software’s capture speed.
Some of the same disadvantages of hard drive camcorders apply to flash memory camcorders as well. Once the storage capacity of the flash memory is reached, you have to make room for new footage by deleting old footage (which hopefully you have already transferred to your computer if you needed to keep it permanently). Again, if you need permanent “hard-copy” backups of your footage make DVDs and store them in a safe place.
Another drawback to flash-based camcorders is their price. Flash memory chips currently cost significantly more than tapes, DVDs, and hard drives. I will not touch on this any more though, since prices are always falling / changing.
In summary, all camcorders must record their movies to some kind of medium. Some camcorders use tapes, others DVDs, others hard drives or flash memory. Each has its significant advantages and disadvantages. My guess is that most people will be looking at MiniDV tape and hard drive camcorders.
High Definition
All consumer digital video camcorders can record standard-definition video, or “SD.” This means about 500 lines of horizontal resolution (the standard Digital Video format specifies 720 vertical lines, 480 horizontal lines of resolution). This resolution has been the standard for years. More recently, we are starting to see the widespread adoption of a newer standard, High Definition, or HD. HD actually encompasses a number of different resolutions and frame rates, as I talked about in the first part of this series. Some camcorders now available on the consumer market can record in HD formats. It is important to note that because HD is compressed digitally, you can record a high definition picture with the same amount of information as an uncompressed, standard-definition picture. In other words, you can record HD to a MiniDV tape. The recording medium of the camera (tape, hard drive, etc) is completely independent of whether or not it records in HD or SD. That being said, I do not know of any company that is pursing an HD camcorder that records to DVDs / Blu-Ray discs.
As far as HD camcorders go, your options for HD will be pretty specific: either they will record in 720p or 1080i. Combined with the fact that HD has a huge color space compared to SD, either 720 or 1080 will look great compared to “normal” SD footage.
HD camcorders will cost relatively more than SD camcorders, although prices are likely to equalize. Once your video is recorded in HD format, it then needs to be edited in HD format as well. You need to make sure that the editing software you use supports the High Definition format. At a minimum, the basic software package that is included with the purchase of your HD camcorder will allow you to do some editing in HD. If you use a 3rd-party program, again make sure that it supports HD editing. This is further complicated by the fact that different HD camcorders use different, competing standards for encoding and compressing the HD video. So you actually have to go a little further and make sure that your software will support capturing and editing your particular HD camcorder company’s flavor of encoding formats. Yikes, huh? Hopefully, all of this gets sorted out very soon and a dominant standard emerges.
Aspect Ratio
The digital video format specifies a certain format for how the picture should be laid out. More specifically, it says that for every 4 lines of vertical resolution, there need to be 3 lines of horizontal resolution.
If that sounds confusing, you can think of it in other terms. If the video is 4 inches wide, it must be 3 inches tall. If it is 24 inches wide, it must be 18 inches tall (4 / 3 = 1.333, 24 / 18 = 1.333). Or look at the resolution of your computer screen. A lot of people use a resolution of 1024x768 on their computer. 1024 / 768 = 1.333.
This 4:3 aspect ratio has been the standard for decades. Look at your standard TV screen; its screen has a 4:3 aspect ratio because it is designed to display video produced in a 4:3 format.
4:3 isn’t the only game in town, though. Most Hollywood movies are filmed in a 2:1 aspect ratio (I think the widest ever was around 2.75:1). This is much “wider” than 4:3 format. That’s why movie theater screens look much more rectangular (wider) than your TV screen. It’s also why many movies in your DVD collection say “This movie has been modified from its original form. It has been formatted to fit your screen.” In other words, the editors had to figure out how to get footage that was originally shot for a rectangular widescreen movie theater to fit properly onto your TV screen, which is squarer. Sometimes, they chop out the sides of the picture. Other times, they “letterbox” the movie, maintaining the widescreen picture but putting black bars at the top and bottom to make it fill up your “taller” screen.
The high definition standard calls for a 16:9 aspect ratio, which is more rectangular than SD format, but still not as “wide” as a movie theater screen. That is why HDTVs look more rectangular than standard TVs.
Some people get tripped up and say, “Wait, isn’t 4:3 the same ratio as 16:9?” It isn’t. 4 / 3 is 1.333, 16 / 9 is 1.777.
At any rate, all of this can be very confusing. Some camcorders will have the ability to shoot in either 4:3 (standard) or 16:9 widescreen, or both. If you have a widescreen TV, you may want to check and see if the camcorder you are purchasing can shoot in a widescreen aspect ratio. All widescreen TVs have the ability to display 4:3 footage on their 16:9 screens (by stretching the 4:3 sideways to make it wider, or by letterboxing the picture vertically) but if you can match your camera to your TV, all the better.
Mixing widescreen footage with standard format footage in the editing process (and vice versa) can be awkward as well. It’s best to pick an aspect ratio and stick with it.
CCDs
CCD stands for Charge Coupled Device. The CCD is the equivalent of the film inside a film camera. The CCD collects the light that comes in, and then makes it into a useable image to be recorded in the video. Almost all consumer Digital Cameras and Digital Camcorders use a CCD system.
That said, there is some variation when it comes to how big the CCD is and how many CCDs there are inside the camera. The bigger the CCD is, in theory the higher the resolution it can record. The more CCDs you use, in theory the more color information you can capture.
First, let’s talk about CCD size. Most consumer level camcorders will use 1 CCD that is 1/6 of an inch across. With a 1/6” CCD, you can get good quality results in the digital video format.
Higher-quality consumer level camcorders will use three separate 1/6” CCDs. The light coming into the camera is split by a prism into three beams. Each CCD has a piece of colored film in front of it that only lets one color of light through, either red, blue, or green. So a full size image is recorded for each separate primary color. These three images are then combined digitally, which results in much greater color accuracy.
At the highest end, professional camcorders use three 1/3” (bigger than 1/6”) CCDs. These cameras cost several thousand dollars, however.
To reiterate, you can get good quality SD results with a single 1/6” CCD, which is what you will find in most consumer camcorders. The bigger the CCDs, and the more of them there are inside the camera, the higher quality your footage will be.
Zoom
Zoom is important to mention, only because of how unimportant it is to your filming. Zoom of course refers to how close you can get in to your subject without actually moving the camera physically closer. Zoom comes in two flavors: optical and digital. Optical zoom is familiar to everyone who owns a digital camera. You can zoom in magnifying the image, and you can zoom out. Inside the lens of your camera there are, at a minimum, two pieces of glass that either move closer together or further apart (they are driven by small motors), and this causes the image to become magnified or become smaller, zooming in and out.
There are of course limits to optical zoom. Either the pieces of glass in the lens physically can’t get any closer together, or they can’t get any further apart (without of course making the lens itself gigantic and unwieldy). The practical upper limit on optical zoom for a camcorder lens is about 30x magnification.
Digital zoom is a different animal. The camera first zooms as far in as it can optically, and then uses a computer to “pretend” what it would look like if you zoomed in further. This usually has disastrous results for the quality of your footage. The bottom line is don’t ever, ever, ever use digital zoom. 30x optical zoom will get you more than close enough, and if it doesn’t, move the camera closer. Furthermore, the more you zoom in, the more every shake and vibration of the camera becomes magnified as well. Try hand-holding a camera at a “digital zoom” of 250x and see how it looks. If you can hold the camera steady enough to even get something recognizable out of the footage, you deserve a prize.
If you’re filming your own strokes and the camera is off to the side of the court, you won’t need more than about 3-5x optical zoom.
Some camcorder manufacturing companies tout zoom as something like the number of CCDs or storage capacity: “the more the better.” This could not be further from the truth, and they do it because many people are confused into thinking that more zoom (or more of anything!) is better. Again, about 30x is about as far as you can zoom in using just optics; you have to invent the rest digitally as you go, and it looks like crap when you do that. Don’t be lured in by big zoom numbers. You’ll never use them, and its all fake after about 30x.
Image Stabilization
Image stabilization is a technology developed to overcome the “shakiness” problem of hand-holding a camera. Image Stabilization (IS), like zoom, comes in both optical and digital flavors.
With optical IS, tiny little motors in the camera’s lens actually move the lenses around to counteract the shakiness and vibration from your hand. This is the “best” system in terms of quality, but it makes the lenses heavier and more complicated. Thus, it costs more. With digital IS, a computer inside the camera tracks the motion of the scene and attempts to stabilize things on the fly. The footage isn’t chopped at the edges by these systems because the CCD inside the camera is actually a little larger than the picture you see through the viewfinder or that gets recorded onto the tape. This leaves a little room for digital stabilizing of the image.
If you mount your camera on a tripod, Image Stabilization isn’t necessary. If you handhold a camera for any of your shooting though, it’s a big plus.
Manual Control
Finally, and very importantly, you want to know what kind of manual controls your camera has over the various picture settings. We have already talked about Shutter Speed, Aperture, and Color Temperature in previous parts of this series. Are these things fully manually controllable by your camera, or are there only various automatic settings? There are also other things, such as backlight compensation, that a camera may offer which can help your footage in certain situations. Again, are these aides manual or automatic?
For the purpose of filming your strokes and analyzing them, the most important things to look for are those manual controls.
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