Still Photography Camera Guide
Optical Zoom, Superzoom and ultrazoom
Optical zoom lens is now the "standard lens" on most if not all compact digital cameras. However, trying to figure out the zoom range of an optical zoom lens for consumer digital camera is not so easy.
In the old days choosing a 35mm film camera with an optical zoom lens is simple because it always says 35 ~ 80mm zoom, 75 ~ 210mm zoom or 28 ~ 100mm zoom. At one glance you can tell if it is a standard zoom or a telephoto zoom or wide angle to tele-zoom.
16 elements 5 groups optical zoom lens
Optical zoom are lenses that have many focal lengths within their zoom range. A wide-angle lens on a 35mm format camera is a lens with focal length below 32mm which gives you a wide or broad view and takes great scenic or landscape shots. A telephoto lens, lens with focal length above 85mm, is for taking images far from you such as sports and nature photos. For taking portrait pictures of people you need a short telephoto lens around 75 to 150mm focal length often called a portrait lens.
Digital camera and optical zoom
However, things are not so simple with consumer digital cameras. Camera makers tend to quote figures such as a 12X zoom or 4X optical zoom. To add to the confusion, some digital cameras actually don't have an optical zoom lens yet it is mentioned as a camera with 3X zoom or 3X digital zoom.(See next section on Digital Zoom vs Optical Zoom).
Even if a digital camera indicates 3X optical zoom of, say 7mm ~ 21mm, that still doesn't tell us much if the image sensor size is not mentioned. We talked about focal length in the optical lens section in the previous topic. So this 3X optical zoom can actually be a standard to telephoto zoom, an equivalent of 50mm to 150mm in 35mm camera format, a great lens for taking portraits. It can also be a general purpose 3X optical zoom, an equivalent of 35mm to 105mm in 35mm camera format, depending on the dimension of the image sensor!
Now imagine this - you are going for a holiday trip. What you need is a general purpose zoom but what you actually bought is a telephoto zoom, because when you saw the 3X optical zoom you got all excited and did not check or ask further for its zoom lens focal length range. Well, what could happen is you would become so exhausted after the second day of your tour because you find yourself keep having to run across to the other side of the road each time you want to take a group picture!!
Due to the fact that imaging sensors come in too many sizes. From the tiny one on the low end Point-and-Shoot compact digital camera to the large one in the 35mm full-frame dSLR and the huge one in the medium format digital SLR camera. Not knowing the actual dimensions of the image sensor, the focal length of the digital camera makes little sense to the photographer.
We are unlikely to see a standard focal length format in digital camera anytime soon. As such digital camera will have to borrow the 35mm film camera equivalent focal length as a common reference point. This is often referred as Equivalent Focal Length or EFL specification for clarity and for comparison purposes.
The open standard FourThirds System initiated by Olympus Optical together with Kodak in 2002 is an attempt to create a standardisation for digital SLR. Since its inception the FourThirds System is slowly but steadily gaining acceptance. Fourthirds members now include FujiFilm, Sanyo, Sigma, Panasonic and Leica Camera AG.
Other leading camera makers are not keen on the FourThirds project for many obvious reasons. One being the FourThirds perceived by rival manufactureres as a competing system. Other reasons include product and systems continuity, support and commitment to their legacy camera users and photographers, etc. As such for Fourthirds System to become a common standard like 35mm film format is certainly an uphill task for the Fourthirds organization.
Nevertheless the FourThirds System does have its merits. Fourthirds system now has many followers with some strong Fourthirds systems support groups and Fourthirds believers. The video below gives a quick overview of the FourThirds concept.
Video on Fourth Thirds System concept
Back to our optical zoom lens. Compact digital cameras with optical zoom range reaching 10X to 18X is getting quite common. They are what many camera manufacturers called the Superzoom or Ultrazoom camera. The zoom range is equivalent to 38 ~ 380mm or 28 ~ 504mm in 35mm format. This is rarely seen in 35mm film camera. An optical zoom lens of this size in 35mm camera will weigh more than 3kg and at least 40cm in length.
If you are using an optical zoom lens of this ultrazoom range on a 35mm camera you will definitely need a tripod because of its weight and size. However, due to the compact size of point-and-shoot digital cameras we hardly see any one using a tripod with this tiny camera with a 10X and above optical zoom range, because it would look funny! and your friends will laugh at you! We suggest if you are looking for a camera with this ultrazoom range, you should make sure it comes with the Image Stabilization system.
The Vibration Reduction or Image Stabilization system is usefull in getting sharp pictures from these utrazoom cameras. Ultrazoom camera often has a small aperture at the long end of the zoom range and this makes the image stabilization system even more important than other lenses. With such a huge zoom range and a small maximun aperture any image stabilization system is still inadequate.
If you are serious on getting the most out of this Ultrazoom digital camera with the 10X or 18X optical zoom, a good solid tripod is a must. This 10X ~ 18X optical zoom also magnifies your hand shake by 10 to 18 times! So if you want to get a good sharp photo with this utrazoom camera without any camera shake or fuzzy image appearing on your picture, a tripod is vital.
No matter what kind of built-in image stabilization system is in your ultrazoom camera, it can only provide stablization support to some extent but will never be sufficient to cover such a wide zoom range. Alternatively limit your zoom range to below 3X when using this camera handheld without the image stabilization system. Go up to about 6X with the image stabilization system and only zoom to maximum when you have solid support for this superzoom camera.
Ask yourself -"do you really need the 10X or 18X optical zoom of 500mm focal length?", "what pictures do you take?". Birds, wild life and sports photographers with subjects that cannot be approached too close may need it.
Most people with a little leg work can live happily with a 3X ~ 4X optical zoom. Cameras with this 3x-4x zoom are now called Practical Zoom camera coined by some reputable camera review websites, simply because cameras with this 3X and 4X zoom range offer a more practical zoom range and aperture opening for general photography.
One final note on the ultrazoom digital camera. Other than bragging being the longest zoom camera around, it has nothing much to shout about in terms of image quality and performance. A zoom lens is always a trade-off for quality over convenience. With such a wide zoom range there are just too many compromises that the camera and lens designer has to sacrifice. You will certainly get a better deal with a Practical Zoom digital camera which often delivers better results than the Ultrazoom digicams and at a much better price too.
© 2003 - 2013 www.stsite.com