STsite's Guide to Still Photography Camera

Image size - The Bigger the Better

The first area in a camera that will determine the quality of the pictures is the dimension of the original images captured in the camera. For a digital camera the image size is measured in the number of pixels. We now find high end consumer digital cameras in the market with image size at 6~8 megapixels.

A megapixel is about 1 million pixels or 1,048,576 pixels. A pixel is short for picture element or one dot on a video screen. A web cam usually has an image size of about 90,000 pixels and will give you a quality picture of about 5cm X 4cm. However the resolution of the web cam is just good enough for what it is designed for -- as a "web" cam and for video phone via the Internet. Compare that to a digital photo with an image size of 5 megapixels you can have quality picture printed at 42cm X 33cm! If all your photography needs is just some 6R photos for the photo album then any 3 megapixels image size digital camera is more then enough. If you need to blow up your pictures to hang on the wall then look for something with an image size above 5 megapixels.

In digital camera the size of the camera is getting smaller and smaller. However, two things in the digital camera are getting bigger and bigger. The first one is the image size in megapixels we just mentioned. The other is the physical dimension of the image sensor. A bigger image sensor has better sensitivity to light and produces stronger signal and allegedly improved image quality, colour fidelity in low light photography mostly due to improvement in signal to noise ratio. However the bigger sensor size also costs dearly. The average consumer digital camera has tiny image sensors with size range of 1/3-in to 1/1.8-in. High end Digital SLR uses the Four Thirds CCD sensor or the even bigger APS-c format DX CCD sensor. The expensive high end professional digital SLR uses the full frame 35mm image size sensor.

Moskva-5 Russian Made 6 X 9cm Medium format folding camera (1956-1969)

Back to film camera, the image size is not measured by megapixel but the size of film formats. The largest one used by professional photographers is called the LF or Large Format camera which has films as large as 8 X 10 inches or 20 X 25CM. This is mostly used for blowing up into big posters and billboards. The next level is the medium format camera that has films around 4.5 X 6cm, 6 X 6cm, 6 X 7cm and 6 X 9 cm. This range used to be the "field" camera of the advertising trade. Medium format cameras normally have interchangeable film-back. Nowadays you can also use digital film-back with them to convert them to a digital camera but you need to have a PC or laptop attached to the film-back to use it.

The next level down is the widely used "standard" 35mm camera format. The image size of 35-mm format is 24 x 35 mm. They have the largest market share for film camera and you can find many models, brands and designs in this area. They produce high quality photo at a reasonable price. This range also has a wide range of lenses and accessories and add-ons. Why 35mm film format is the most widely accepted format? Because this format has the best compromise in terms of price, physical size and quality. Generally the inexpensive 35mm cameras still produce better quality pictures than digital cameras costing 2 to 3 times more (at the time of writing). 35mm is still widely used though the large part of the market share is now taken over by digital cameras. There are still a large group of diehard 35mm users who insist on using their old fashion classic antique camera and nothing else.

Lower down the range is the APS film format which was designed by Kodak in alliance with some Japanese camera makers to make photography easy for the masses and hopefully to replace the 35mm film format. The image size for APS format is 17 X 27 mm. The APS film is stored in a tiny cartridge even after processing so you can't see or touch the film and an index sheet has to be printed and kept with the film for reference. What this APS format is designed to do can actually be performed better with a digital camera and as far as picture quality is concerned it is well below the 35mm format. Recently some camera manufacturers has stop producing APS camera including Kodak the inventor of the APS system! However, APS films are still available in limited supplies.

Be it the modem digital camera or the traditional film camera, as far as image quality is concerned the dimension of the image size is paramount. You can micro miniaturise electronic chips or reduce the size of the digital camera but you cannot cut corners for image size. The bigger the better is still true - remember the disappearing of the Kodak Disc camera and the 110 film format? That was all due to the film size being too small and produced poor quality grainy photos. However large image dimension can be a problem too. In film camera it resulted in a large and heavy camera and it also cost you dearly. In digital camera a larger image size results in high memory usage, long processing time and requires a high-speed microprocessor or CPU, heavy battery consumption and generates more heat.

An image size of 3~5 megapixels is a good bet for today's digital camera. Of course this will change as the price of electronic chips lowers and CPU speed increases and new battery that lasts longer become available. For the film camera the 35mm film format seems to be the best compromise for size, quality and price. The important point here is use the right tools for the right job; it will be crazy to set up a 8 megapixels image size camera for web cam or video conference over the Internet. Stick with your cheap web cam for those applications.