The Lens
As mentioned previously , the first measure in recording a television image is to focus light onto the CCD , using a crystalline lens .
To get a camera to record a clean-cut pic of an object in front of it , you take to be capable to adjust the focus of the lens – that is , move the lens system so it propose the light beams coming from that object precisely on the CCD . So , just like film television camera , camcorders let you move your crystalline lens in and out to focus light . Of course , most multitude need to move around with their camcorder , shooting many different things at different distances , and constantly refocusing is extremely unmanageable .
This is why all camcorders come with anautofocusdevice , unremarkably an infrared beam that bounces off objects in the center of the frame and comes back to a detector on the camcorder .
To find the distance to the object , the processor calculates how long it takes the beam to spring and return , multiplies this time by thespeed of lighter , and part the production by two ( because it traveled the distance twice – to the objective and back again ) . The camcorder has a smallmotorthat move the lens , focusing it on aim at this distance . This works pretty well most of the time , but sometimes you have to overrule it – you may want to focus on something in the side of the frame , for example , but the autofocus is picking up what ’s right in front of the camcorder . To larn more about autofocus mechanisms , check outHow Autofocus Cameras Work .
Camcorders are also fit out with azoom lens . In any sort of camera , you could magnify a panorama by increase thefocal lengthof the lens of the eye ( the space between the lens and the film or CCD ) . Anoptical zoomlens is a exclusive lens system whole that lets you change this focal length , so you could move from one blowup to a closer magnification . Azoom rangetells you the maximum and minimal blowup . To make the soar function easier to use , most camcorders have an attached motor that adjust the zoom lens in response to a simple toggle control on the grip . One vantage of this is that you’re able to go the zoom well , without using your liberal hand . The other advantage is that the motor adjusts the lens of the eye at a firm speed , making rapid climb more mobile . The disadvantage of using the grip control is that the motor drainsbatterypower .
Some camcorder also have something telephone adigital rapid climb . This does n’t take the camera ’s lenses at all ; it simply soar in on part of the entire picture captured by the CCD , magnifying the pixels . Digital zooms stabilize magnify photo a little better than optical zooms , but you give settlement quality because you end up using only a portion of the available photosites on the CCD . The personnel casualty of resoluteness makes the image bleary .
One of the great thing about a camcorder is that it can adjust automatically for different levels of light . It ’s very obvious to the CCD when an image is over- or under - unwrap because there is n’t much variation in the charges collected on each photosite . The camcorder monitors the photosite charges and adjusts the camera’siristo let more or less twinkle through the lenses . The camcorder computer always work out to exert a good contrast between benighted and light , so that images do n’t appear too dark or too washed out .
