Controlling The Camcorder Lens
Controlling The Camcorder Lens
Tim Smith (Camcorder Training Specialist) gives expert video advice on: What is the difference between an "optical zoom" and "digital zoom"?; Should I ever turn off my camcorder's image stabilizer? and more...
What is the "zoom" function on my camcorder?
Every camcorder out there has some sort of a zoom--from the old days when they were no more than maybe three or six power up to these days where they can be 20, 25 even 35 power zooms. What you would do that for, you want to get closer to the subject but you just can't, so as you zoom in it magnifies the image optically, we're talking about optical zooms now, optically to put that image down onto the image sensor in a larger format. It's great for composition, gets you just into the action that you couldn't be in any other way.
What is the difference between an "optical zoom" and "digital zoom"?
When you're selecting a zoom, you're going to have a choice between either the optical range, or the digital range, and pretty much every camcorder out there has both optical and digital zoom. What you really want to look for is the optical zoom. It has the best picture quality. When you move past the optical range into the digital range, you're now, instead of optically magnifying the chip, doing it electronically. You're blowing it up on the chip itself. It'll make the image look closer, but the more you go into the digital world, the digital zoom world, the poorer the picture quality gets. So really, if you have to, go for a digital zoom, but try to keep it in the optical zoom world for your best picture quality.
What is an "image stabilizer", and why would I use it on my camcorder?
A few years back, companies started putting stabilization systems on their camcorders and now they're pretty much common on every camcorder. The idea of a stabilization system is to keep an image as stable as possible, especially when you're holding a small, light cameras that are difficult to hold steady. The only time you don't want to use a stabilization system is when you're on a tripod or the camera is not moving; that can tend to fool the stabilization system and give you some things you don't want to do. Most of the time however, it's a good idea to leave your stabilization on, particuarly if the camera is handheld.
How do "optical" and "electronic" stabilizers differ?
An optical stabilisation system is really two pieces of glass held together with an accordion-style bellows. When the camcorder senses any kind of vibration it flexes that bellows to bend the light through this optically pure liquid that's in between them, so it always hits the chip nice and even. The biggest advantage to that is that there's no loss in picture quality; there's no loss in resolution when you're engaging an optical stabilisation system. However, a lot of camcorders (especially in the lower price range) have an electronic stabilisation system. That electronic stabilisation system stabilises the image by moving it around on the chip. So, if the camera starts to vibrate it changes where that information on the chip comes from. If this was your chip, and you wanted to stabilise electronically, as you move the image on the chip moves with it. It does a pretty good job these days, but it will cost you a little bit in resolution when electronic stabilisation is on. Optical: still better, but electronic is working pretty well these days.
Should I ever turn off my camcorder's image stabilizer?
All camcorders have a stabilization system, but strangely enough they also have an on-and-off switch for that. If stabilization seems like such a great thing, why would you want to turn it off? Well, there's a couple of reasons. If batteries are a big concern—stabilization does draw more power than not having it on, although it's not too significant. The biggest issue is that there are some gyroscopic sensors in all these cameras, that are looking for vibration, and vibration happens in a circular pattern, so if you've got this camera mounted on a tripod or setting flat on a table, it's not going to sense vibration in a circular pattern; it's only going to see it in one pattern, in a horizontal pattern. So, leaving stabilization on tends to cause an anomaly called a float—you start to pan between the left to right or you move your camera from left to right and at the end of it, because it's looking for vibration happening this away [in a circle] but only seeing it happening this way [side to side]. The image might continue to move a little bit at the end of your pan. So, it's really best any time you've got the camera locked down on something solid, turn the stabilization system off.