STsite's Guide to Still Photography Camera

Optical Zoom

Optical zoom are more commonly seen than the traditional 38 or 50mm standard lens on most cameras now. Choosing a 35mm camera with an optical zoom lens is easy because it always says 35 ~ 80mm zoom, 75 ~ 210mm zoom or 28 ~ 100mm zoom. At one glance you can tell it is a standard zoom or a telephoto zoom or wide angle to tele-zoom, and you can somehow know if it fits your intended purpose.

A wide-angle lens on a 35mm 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 sometimes also called a portrait lens.

However, things are not so simple with digital cameras. Camera makers tend to quote figures such as a 12X zoom or 7mm ~ 15mm 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 says 3X optical zoom or 7mm ~ 21mm that still doesn't tell us much if the image sensor or the CCD size is not mentioned. Remember we talked about focal length under the 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 or CCD!

Now imagine this - if you are going for a holiday trip, what you need is a general purpose zoom but what you actually bought is this telephoto zoom, because you got all excited when you see this 3X optical zoom range without checking or asking further for its focal length range. Well, what could happen is you would become so exhausted after the second day of your tour because you find yourself having to run across to the other side of the road every time you want to take some group picture!!

Until there is a standardised physical dimension or agreed format for the image sensor or CCD, we will not see a clear cut standardised focal length lens specification on digital camera that will make sense to the end user and photographer. For now the digital camera will continue to borrow the 35mm camera format equivalent focal length specification for clarity and for comparison purposes.

Olympus Optical envisaged the need for such a standardisation for digital camera hardware in 2001 and started working with Kodak on this project in 2002. Kodak and Olympus address this issue with the Four Thirds System standard for digital SLR system. Kodak and Olympus are both members of the Universal Digital Interchangeable Lens System Forum, an industry forum that promotes the acceptance of the Four Thirds System by camera manufacturers. The Four Thirds standard works on the need for a standardised hardware for digital cameras. The first Four Thirds System camera was announced by Olympus in March 2003 -- the Olympus E-1 digital SLR camera system using KODAK KAF-5101CE image sensor.

Will this Four Thirds System standard work? It depends very much on the acceptance of the Four Thirds System standard by other camera and CCD manufacturers. FujiFilm is the third member of this Four Thirds system. The other members now include Sanyo, Sigma and Panasonic. Currently Olympus and Panasonic are the two manufacturers that are producing Four Thirds System cameras with Sigma manufacturing some Four-Thirdsdigital lenses.

Panasonic has formed an alliance with Olympus on a project to develop Panasonic SLR cameras in early 2005. The first Panasonic Four Thirds system interchangeable-lens digital SLR camera the LUMIX DMC-L1 hit the market in March 2006. The LUMIX DMC-L1 comes with a LEICA D VARIO-ELMARIT 14-50mm/F2.8-3.5 lens. This Four-Thirds system LEICA D VARIO-ELMARIT 14-50mm/F2.8-3.5 lens is compatible and available to other Fourth-Thirds camera owners as well. This is good news for Four Thirds system enthusiasts as they now have 2 strong companies producing Four Thirds cameras and lenses. This also marked the arrival of a brand new member to the Four-Thirds system -- Leica Camera AG of Germany who announced their participation and endorsement of the system on Feb 2006.

Other leading camera makers such as Nikon are currently steadfast on the DX CCD sensor an APS format image sensor. However there are indications that Nikon R&D is currently working on a totally new "ground breaking" 35mm full frame format professional digital SLR. Canon is busy improving their full frame 35mm format digital SLR camera which at this moment is only available on the expensive high end Canon professional digital SLR. These developments narrow down the professional market to 3 competing standards and is a first step towards standardisetion. Unfortunately there are no clear signs that there will be anything like this in the consumer digital camera market for now.

Back to our optical zoom lens we now see digital cameras that offer optical zoom range above 8X or 10X in quite a compact camera body. This range usually is an equivalent of 35mm format of 40 ~ 320mm or 38 ~ 380mm. This is rarely seen in 35mm film camera, for optical zoom lens of this size will usually weigh more than 3kg and at least 30cm in length. If you are using an optical zoom lens of this zoom range on a 35mm camera you will definitely need a tripod because of its weight and size. However, due to the compact size of digital cameras we hardly see any one using a tripod with this tiny camera with a 10X optical zoom because it would look funny! and your friends will surely laugh at you!

However, if you are serious on getting the most out of this digital camera with the 8X or 10X optical zoom a good solid tripod is a must. Why? Because this 8X optical zoom also magnifies your hand shake by 8 to 10 times! So if you want to get a good sharp photo with this camera without any camera shake or fuzzy image appearing on your picture a tripod is a must. Alternatively limit your zoom range to below 3X when using this camera hand held, and only zoom to the 8X or 10X range when you have solid support for this camera. Ask yourself "do you really need the 8X or 10X optical zoom of 300mm focal length". "what pictures do you take"? Birds, sports and wild life photographers may need it but most people can live happily with a 3X optical zoom.

Though we see digital cameras having 8X and above optical zoom range becoming common but this is usually on the telephoto end of the optical zoom range. We barely see wide-angle zoom such as 28 ~ 85mm optical zoom lenses in 35mm equivalent in digital cameras. Currently only a handfull of consumer digital cameras have a built-in wide-angle optical zoom.

Digital cameras higher than 5 megapixels with a bigger image sensor are more likely to have a wide-angle lens than those with lower megapixels. We mentioned earlier, wide-angle lens has a shorter focal length than standard lens - about one half of the standard lens. A wide-angle lens on today's consumer digital camera will be having a focal length of about 4mm. This will be so close to the electronic film that it will be challenging for the engineer to get things right; it will even be more challenging or near impossible if you want a super wide-angle of say 17mm in 35mm camera format. (Bear in mind that the focal length is measured from the center of the lens to the film surface not from the rear end of the lens to the film surface). On top of that wide-angle lens demands better image resolution than standard lens or telephoto lens.

The tiny image sensor or CCD used in low end consumer digital camera presents even more challenge and demands higher precision in developing a wide-angle optical zoom for such a camera. In layman terms this adds up to the total cost of camera and results in them becoming very expensive. So for low-end consumer digital cameras we are unlikely to see them being equipped with a wide-angle optical zoom lens. This is sad, for wide-angle lens is such a beauty once you have learned to master it!