Camcorder Lens
Your video camcorder lens has an important role in passing light onto the internal imaging device. It also provides the means by which you can vary the amount of light and adjust the focus or picture sharpness.
Some camcorder lens will have a knurled focus ring on the lens barrel. These are to manually focus the lens by turning the focus ring. Others will allow focus adjustment either manually or automatically, known as auto-focus.
Camcorder lens also offer the abiltiy to zoom into or out of objects in the frame in order to increase or decrease the maginfication.
Letting the Light In
Camcorders use what is called a Charged Coupled Device (CCD) to absorb the light into the camera. A CCD is one of the most critical components of your digital video camera. It has a photo-sensitive surface that collects a piece of data known as a pixel or picture cell. The CCD converts the light and color information into an electrical charge. For most cameras, the larger the CCD suface area, the more pixels it is capable of generating, and the higher quality images it reproduces. Most comsumer grade digital video camcorders have CCDs whose size typically range from 1/6" to 1/3". Some video camcorders have one CCD, but the better quality ones are three CCD camcorders.
Because the CCD reacts to light, the more light you can give it the better the resulting images will be. Obviously the smaller the CCD the lower the quality of the image and the larger the CCD the higher the quality of the image. A pro-sumer grade or professional camcorder has CCDs that are 1/2" or larger. The smaller CCDs in consumer grade cameras have to work much harder to produce a high quality image.
If you're shopping for a video camcorder, it's best to get the largest CCDs you can afford and one with three CCDs rather than just one.
Focal Length
You've all seen camera shots when a distant object appears as if it's coming closer and begins to fill the frame. You've also seen shots where the camera appears to be very close to an object and then begins to zoom out and you find out that the object that once filled the frame is quite a distance away. These shots are made using a zoom lens. This is done by using a lens that allows you to vary the lens focal length.
A lens focal length is measured in millimeters (mm). You may have used a still camera that came standard with a 50mm lens. Other still lens may be measured at 85mm or 200mm. These are known as fixed focus lens because the focal length is fixed at 50mm, 85mm, 200mm or whatever the lens is. A zoom lens can vary the focal length between a minimum and a maximum distance. Focal length in a camcorder is the distance between the CCD and the rear most element of the lens.
It's not uncommon to see a camcorder with a zoom lens rated as 10X or 10:1. This means that if the lens has a minimum focal lenth of 4.5mm, it will have a maximum focal length of 10 times that or 45mm. If the lens has a minimum focal length of 5mm and it is rated at 12X, then the maximum focal length would be 12 times 5mm or 60mm. The zoom lens then would be able to vary the focal length between 5mm and 60mm.
Optical and Digital Zoom
The Optical zoom gives the highest quality image because of the characteristics of the glass lens. As explained above, it is the image resulting from varying the distance between the rear most element of the glass lens and the CCD. Most camcorders also have an additional zoom option known as a digital zoom.
Some camcorder manufacturers may advertise their zoom lens at 700:1. This digital zoom is far beyond that which is possible by physically manipulating the distance between the lens and the CCD inside the camera, so it "artificially" magnifies the image to make it appear as if you are zooming in.
Digital zoom is an electronic process that enlarges the pixels. The downside to using the digital zoom feature on your camera is that as the electronic process artificially magnifies the image, the image becomes fuzzy and it looks as if it's out of focus. Similar to what happens when you enlarge a graphic image beyond it's original size in photoshop, the image becomes pixelated. This results in poor quality video. To get really clean and high resolution video, most videographers suggest not using the digital zoom features.