How Camcorders Work
How Camcorders Work
Tim Smith (Camcorder Training Specialist) gives expert video advice on: How does a camcorder work?; Why don't consumer camcorders work well in low light? and more...
How does a camcorder work?
You know, a camcorder's a very sophisticated piece of electronics, but essentially, you've got an image that has to pass through glass, just like any image even from our still days. Now the difference is the CCD. If you have a film camera, you've always put the image on to some sort of fim and it's exposed it, it's been in exposure. Well that's what a CCD is, it's essentially the film of a video camera. What we're doing is we're taking information through a piece of glass and then we're converting it to an electronic signal, and we do that with the image censor. So we focus that image information on that image censor with the glass, boil it all down to electronic information, whether it's analog or digital, it all has to be moved into an electronic world and from there we move that information onto some sort of media, whether it's tape or whatever, it has to be recorded to something. So really its just a matter of acquistion, meaning getting the information through the lens, turning it into something that the format can store it on through the CCD and then laying it down onto some sort of storage device like tape.
What is a "video chip"?
An image sensor. That's the point of a camcorder; it turns that information from an analog world into some sort of electronic pulse or into a digital world. Its no different than the audio where you turn sound into either a frequency or you turn it into a zero on one in a digital world. That all happens in the video chip - image sensor - itself. Really that's the heart of a camcorder, that's where the image is first dealt with and turned into any kind of an image that we can record and store. Camcorders have come a long way.Currently we have things like CCD or CMOS video chips. Both of those are different types of image sensors that handle this information and then reduce it to a format or formula that can be recorded, something that can be laid down on tape. Whether it's the CMOS video chip or it's the CCD video chip really that's where the information is handled and turned into something we can store.
What's the difference between a "CCD" and a "CMOS" chip?
If you've bought a camcorder recently, you've either bought a camcorder which has what's called a CCD, or what's called a CMOS. Both of those are different types of image sensors where the information is electronically converted to either zeroes and ones or electronic impulses that can be recorded and taped to frequencies. There's advantages and disadvantages of both. The older technology is the CMOS – is the CCD, I mean. It's a very tried and true format. It's something we've used for years. It's going to continue, probably, in cameras for a long time. The newer technology is now called CMOS – and that's something that's come over from the still cameras. CCDs can be used on expensive cameras, and so can CMOS. The most expensive cameras in the world these days are CMOS cameras – and they're single chips. CCDs can tend to be a single chip or three-chip. So, it's really a matter of which technology you want. Now, let's talk about a little bit of the advantages. The advantages of CMOS is, in some ways, we can produce the image of a three-CCD camera off of a one-chip camera. So, it's less expensive for us to produce, but they don't compromise picture quality. CMOS is really a great piece of technology and you're going to find that more and more prevalent in camcorders as we go from here on. What's the big advantage to CCDs? Well, CCDs is a technology that we've known for years. We can produce them relatively inexpensively and we've been able to reduce their size over the years and still maintain their performance. So, CCDs, I think, especially in lower-end cameras are going to be around for a while. It doesn't mean they're bad – it just means they're older technology – but it tried and true technology. And, I wouldn't necessarily shy away from a CCD camera if the performance is there.
Why would I need a 3 CCD camcorder instead of a single chip CCD camcorder?
You're looking at camcorders and you've got a couple of choices to make. Some of those choices might be whether or not you want to buy a single chip camcorder or a 3-chip camcorder. Well a 3-chip camcorder uses 1 chip for red, 1 for green and 1 for blue and all colours are created by either the additions of red, green and blue or subtraction of red, green and blue on the colour palette. So 3-chip camcorders, generally speaking, give you the best picture quality. Single chip camcorders rely on 1 chip to produce all colours in the spectrum and that can be done with different types of filtering systems. In general a 3-chip camcorder is going to give you a better picture quality than a single chip camcorder.
What is "pixel count" and how does it affect the image quality of my camcorder?
One of the biggest buzz words I guess or one of the biggest technical terms these days in terms of buying a camcorder or even a still camera, is what's the pixel count. Is it a six mega pixel; is it an eight mega pixel? When it comes to video, pixel count isn't as important as you might think because we're not using pixels the same way you do when you buy a still. When you buy a five mega pixel video camera, you're not using all five mega pixels to produce a video image, even a high definition image is really only between one and a half to two mega pixels of information. So, what are those additional mega pixels used for? Well, they can be used for things like color temperature for your color balancing, for your white balancing. Or, really, they're used for the still capabilities of a still camera. So, you want the best image you can get, but don't always rely on just what the pixel count is to determine if that's what you're getting your best image from.
Why don't consumer camcorders work well in low light?
You've got a camera, and maybe it's not performing as well in low light as you think it should be. If you think about the way a camera is designed, or the way a chip is designed, it really can't be perfect in low light and then perfect in bright light. It's not a sliding scale. What a camcorder manufacturer has to make a decision on, when we're producing a camera is, do we want optimum performance to be in good existing light, or do we want it in a low-light environment? If you were in the market to purchase a security camera, you might find one that performs very well in low light, but doesn't handle the high lights very well. However, what we're looking for is a camcorder which most people are going to use in most lighting conditions. If you're shooting in your average lighting conditions, these cameras work great. If you find that you're going to be in a low light environment, it's probably a good time to try to turn some more lights on.
What is the difference between "NTSC" and "PAL"?
Camcorders come in all sorts of flavours, especially when we're referring to standard-def camcorders. One of the things you're going to see, or one of the things you may already know about, is that you probably have either an NTSC camcorder or a PAL, depending on where you live. NTSC is kind of the format that's used in the US, PAL is a more European format. NTSC is also a format used in the Asian countries as well. So really you need to buy the camera that fits your format, or fits the country that you're living in. It has to do with the standard that you're going to play it back on. An NTSC television standard plays NTSC tapes. A PAL standard, for the European standard, more or less, plays the PAL tapes. The important thing to note is that images that were shot in one country can't easily be transferred to another country. The PAL format is colour. It's one system: Phase Alternating Lines. The NTSC system was delivered here because we had such a base of televisions in the US that the world didn't have, but it was a black-and-white standard. So, when we moved to NTSC, the colour standard, we had to incorporate a black-and-white signal on to the colour signal, so that black-and-white TVs weren't obsoleted. In the European system, when they went to the colour standard, all the old TVs just went out the door. One day, they wouldn't work. They wouldn't let that happen here. So we had to come up with a system that was a compromise of both. PAL's always been a better system, but it would have obsoleted every set that was on the market at the time. Now the good news is, as we all move to high definition, this will become much more standardised, and we'll be able to pass information from country to country without having to deal with the difference in formats. That's one of the advantages of living in a digital world, and moving to high definition. However, in standard definition, we still have to deal with the controversy between NTSC and PAL.
What is the difference between SP, LP and EP recording modes on my camcorder?
All camcorders have different recording speeds and different record modes like SP or LP even ELP, which is extended long play. SP is your standard recording mode. That is really going to deliver. In an analog world, it will deliver best picture quality. If you recorded in SP you got best picture quality and as you increased your record time to, say LP or long play, or even in some cameras ELP - extended long play - you got a lot more record time, but it did cost you in picture quality. The resolution dropped with each addition of record time. Now we're kind of working in the digital world and that is really not true anymore. When you go from SP to LP, you really do maintain the same picture quality and get more out of the tape, but a word of caution here: when you go from SP to LP, many manufacturers - and we state these in our manuals - will not guarantee that that tape is going to play back on anything but the camera you recorded it on, so you have to be a little bit careful. Use LP mode when you have to, but try to stay in SP most of the time because you don't want to end up with a tape that you can't play back on somebody else's camcorder or deck or maybe even on the next generation of camcorder you buy. So, use LP, but use it sparingly.
What is the difference between "interlaced" and "progressive" video?
In the last couple of years, camcorders have added a feature called "progressive," or in some instances, it's called "frame mode." It's essentially the same thing. It's an offset to what's called "interlaced." Camcorders and television have been interlaced since day one. It means that you have a frame of information which is like this, and those frames are two fields of information, two lines of information. If we go back in the early days of television, really what happened was in TV sets, the actual screens weren't really fast enough to produce an entire frame of information, so they broke it up into two fields, so it would, again, write fields one, then three, then four, then five and they could fill it in. What happened was the sets, the phosphorus would go out before it would fill up the entire screen. So they figured the best way to get the information to the screen was to bring it in in two different pieces.And that worked well for years, but really, ideally, we want all of that information, just like film, to be a solid frame. So sets are better now, computers are better now; we can handle an entire frame of information. We can move on to a frame mode, or a progressive mode, depending on the camera you own, to get an entire frame of information recorded at a single time. Really important, especially if you're looking for either the film look, or really are going to actually do a film transfer and end up in film, you really want to shoot progressive that way, or detail on progressive.Now, there's not really a compromise to progressive, but the equipment that you're using has to handle progressive as well. Televisions, for the most part, are still interlaced. So you have to consider that all the way across the board.
What is "24p" and why would I use it?
24p is a new feature added to cameras over the last couple of years that the filmmakers have really grabbed on to. Traditional filmmakers, and by that I mean people who actually shoot on film instead of video, are especially fond of it because it allows inexpensive video footage to have the cinematic quality captured by 'film'. When you go to a theater and you sit down in front of a screen, you're watching 24 frames being projected per second, video has always typically been 30 frames per second. Getting to 24 allows for more of a film look. We do some things in the camera, the way we sample the information off the tip, and the way we put the information on the tape, to try to get there. Now, one of the things you have to know is what's coming out of that camera is always 30, it's not 24 even if we recorded it that way. So shooting 24 frame really means 30 on tape with a 24-frame cadence.
Can my camcorder play back the videos I've shot?
All camcorders have the ability to be a VCR, a playback deck. I recommend it. I understand when people don't want to use the camera as a deck to play back videos, because it is true that the more you use a camera, the more you wear it out. But believe me, these cameras were built pretty well, and they really were built to be used as a deck to play back videos. Now, if you're a high intensity industrial user, maybe that doesn't apply. But for most of us, we can use these cameras as decks to play back film and it'll never be a problem.