Since we checked out the myth of Megapixels in a past post, you know what to look for in terms of megapixel count for the new camera you want to buy.
Today we look at another of the camera salesman’s favourite buzzwords – The camera zoom.
Zoom, in terms of a camera, is the ability of the camera lens to focus on a subject at progressive distances from the camera. The ability of the camera to magnify the subject so as to capture greater detail or to very simply, get close to the subject, which in reality can be very far off.
In my past post about focal lengths, we saw how zoom or subject magnification actually worked. By varying the distance between the lens and the image sensor, the angle of viewing is narrowed down. This focuses the camera’s image sensor on a smaller portion of the subject, thus causing it to magnify.
So very simply, the greater the ability of the camera to magnify subjects further away, the better the zoom capability of the camera.
However there is a catch. There are in reality two types of zoom in digital cameras, optical zoom and digital zoom.
Optical zoom or mechanical zoom is the method of zoom explained above. The magnification is achieved by physically changing the distance between the lens and the image sensor. This needs a mechanical way to move the lens and is most commonly done using a telescopic mechanism like the one pictured below.
Because the optical zoom does not manipulate the captured image in any way, the result is a clearer and sharper magnification.
Digital Zoom is the cheaters way to zoom, available only to digital cameras. As there is no film in the digital camera and the captured image is electronic information, this allows the camera to manipulate the electronic image in many ways which were not possible with film.
The magnification of the picture is done by image manipulation rather than any physical movement of the lens. The area of interest in the digital image is cut out and magnified by expanding the pixels. Now while this technically works for a small expansion, doing this too much causes the picture to blur and lose focus, not to mention giving it a very grainy look.
As an example of the quality difference, look at the picture below.
As can be seen, while a optical zoom would give you a sharper clearer magnified image, the digital zoomed image is blurred and pixellated. Even though the image is magnified to the same extent, the usability of such an image greatly reduces.
So, when you go out to buy a new camera, ask for one which has a larger optical zoom. Never settle for only a digital zoom even though these cameras are a lot cheaper. Most of the time the camera salesman may not know what type of zoom is present in the camera. In that case, ask to see the specifications of the camera and look for the word “Optical Zoom”.
Nowadays, most cameras have a combination of optical and digital zoom. The zoom range begins with optical zoom [with the telescopic mechanism coming out] till about 4X – 6X and then goes further to digital zoom. While this effectively would give you a large combined zoom range, remember that the useful zoom is the optical part. The digital zoom for around 2X more would help, but anything more than that is a gimmick.
Usually 4X to 6X optical zoom is good for any point and shoot camera and should cover most photography situations. Special prosumer cameras, called super zooms, feature optical zoom ranges of up to 20X. These are useful for the hobbyist.
dSLR cameras have the option of interchangeable lenses. As a result, special lenses and lens attachment combinations enable the camera to have an incredible zoom factor. These lenses have the telescopic mechanism within and allow fine adjustment of the zoom to enable tack sharp images. Some of these lenses cost more than the camera body itself !!!
The rule of thumb in the shop is – Buy as much optical zoom that is possible within your budget.
As always, please leave your comments. Until next time……………………
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