[Adapted from an article written for Digital Photography Made Easy magazine, 2002. It has been updated to take into account 4 years of development and falling prices]
Anatomy of a digital camera
Ever wondered what the inside of a digital camera looks like? Put that screwdriver down and read this instead
There are over a hundred different models of digital camera available at the moment, ranging from less than fifty pounds to more than five thousand. They all look very different, but under the skin they all work in much the same way. Over the next few pages, we’ll take a look under that skin, and try to try to explain what all the different parts of the camera do, and how they can be useful to you.
You don’t need a degree in optics and another in electronics to take a photograph, but a basic understanding of how a digital camera works will save you being caught out when you come to buy a new one. If you know which questions to ask, you’ll avoid paying more than you have to, but still get a camera you will be happy with.
Knowing how your camera works will also help you to appreciate the technical capabilities of the one you eventually choose. If you know what the camera can and can’t do, it will improve your photography and help you to avoid taking any embarrassingly duff shots. The anatomy of a digicam needn’t be a mystery, but you don’t have to dismantle yours to find out how it all works.
Which digicam is right for me?
Funcam: Costing around £50-£70, funcams take pictures no bigger than 640 x 480 pixels and have CCDs no bigger that 1 megapixel. They are normally fully automatic and can often double as webcams. With the falling price of good compacts they are disappearing from the market.
Compact: Costing from £100 to £200, and ranging anywhere from 3 to 8 megapixels, most compact cameras have 3x optical zoom lenses and mostly automatic operation. They are easy to use and ideal for snapshots.
Mid-range: Costing between £200 and £400, mid range cameras will usually have a higher specification than a basic compact, with bigger, better quality zoom lenses, more manual controls and advanced features such as anti-shake.
Pro-sumer: Top quality cameras costing from £400 to £600 pounds, with 6 to 9 megapixel CCDs. They have a full range of manual exposure options and powerful zoom lenses. They are usually larger than mid range cameras, with SLR-like styling.
Digital SLR: For serious professional photographers or keen hobbyists, these cameras cost between £600 and £5000, can take a wide range of interchangeable lenses and other accessories, and are between 6 and 15 megapixels.
Megapixels and resolution
The word you’ll often see associated with digital cameras is “megapixel”. It is an indicator of the power of the camera, and generally more megapixels equals a higher price tag. When buying a camera, it is important to know what you need, otherwise you may end up spending more than you need, or worse end up with a camera that holds you back with its limited capabilities.
As a rough guide, if all you want are images to go on your website or to email to your friends, then a funcam or one megapixel compact is all that you need. They produce image files of about 1,280 x 960 pixels, which are too small for good quality prints.
If you want snapshots to print, you’ll need a camera of about 3 to 4 megapixels. These produce images of at least 2,000 x 1,500 pixels, which are ideal for printing out 6 x 4 inches.
If you are a more experienced photographer looking for a camera that you can use creatively, you’re going to need to spend a little extra and go for at least 5 or 6 megapixels. An image file of around 2,500 x 1,900 pixels can be printed at up to 7 x 9 inches with no loss of quality.
What about batteries?
It is a well-known fact that digital cameras do for batteries what a fat bloke would do for a pie shop. There are only two ways to keep up with their appetite for energy. Either buy a controlling interest in Duracell, or invest in a couple of sets of rechargeables. There are several different types of rechargeable batteries on the market, but the best type for digital cameras are high-capacity Nickel-Metal Hydrides, or Ni-MH for short. They have a number of advantages over older Nickel-Cadmium batteries. They are quicker to recharge, they last longer, and they don’t suffer from the ‘memory effect’ that causes NiCads to lose part of their charge capacity if not fully discharged before recharging. A good quality set with a charger will set you back about £15.
Most digital cameras now come with proprietary Lithium-ion rechargeable battery packs, which are smaller, lighter, more powerful and operate better in cold weather than Ni-MH batteries.
Thanks to recent advances in the field of optical design, many digital cameras now have small but powerful zoom lenses equally as capable as the bulky optics found on the front of traditional SLR film cameras. Because the different sizes of various camera CCDs makes referring to the focal length of the lens unhelpful, most digicam zoom lenses are usually described in terms of their maximum magnification. 3x optical zoom is about the average at the moment, but some cameras boast lenses with up to 12x zoom capabilities.
It is important to distinguish between optical zoom and digital zoom. The former refers to the magnification of the lens, while the latter refers to a process whereby the centre pert of the image is enlarged electronically. Because this degrades image quality, it is best avoided.
The imaging chip
At the heart of every digital camera is an imaging chip, or light sensor. There are two main types. Cheaper digicams, such as sub-megapixel funcams, tend to have low resolution CMOS chips, because they are cheaper to manufacture.Most digital cameras have what is called a CCD, or charge-coupled device, which consists of a grid of millions of tiny silicon light sensor cells. Each cell can only sense brightness, so they have a mask of red, green and blue filters over them to enable them to detect colour.
Some manufacturers, most notably Canon, use high-specification CMOS-type sensors in their higher-end cameras. This technology has a number of advantages, not least lower manufacturing costs.
A new kind of chip has just been developed which is based on CMOS technology but has over three times the resolution of conventional CCDs. This is the Foveon X3 chip, but at present it is only available in a few cameras.
Don’t forget memory cards
All but the most basic digicams will have some sort of removable storage device. Some unusual cameras have used mini CD-RW or magneto-optical discs, a few have even used floppy discs, but the vast majority use small solid-state flash memory cards.
There are several different types on the market, with different advantages to each. The most common type is Secure Digital, or SD card. Despite their diminutive size, these cards are available in sizes up to one gigabyte of storage capacity. They are used in PDAs and mobile phones as well as digital cameras.
More popular in professional and semi-professional cameras are CompactFlash cards. They come in two different types, with Type II cards being thicker than Type I. They are available in capacities up to 4 gigabytes, and are very durable and reliable. The IBM/Hitachi Microdrive is a tiny hard disc unit the same size as a CompactFlash Type II card, and is available up to 4GB.
A relative newcomer is the tiny xD Picture card, developed by and currently only used by Olympus and Fujifilm. Despite their small size, the clever architecture of these cards means their potential maximum size is as high as 8GB, although the largest size currently available is 1GB.
Finally, there is the Memory Stick. This is a proprietary Sony device, and hasn’t been successfuly adopted by any other digicam manufacturer. There are many different varieties of Memory Stick, with sizes as large as 1GB. They are quite expensive compared to other types of memory card.
Another common feature on digital cameras is the LCD monitor screen for viewing your pictures and using the menu control system. Manufacturers are making big improvements to these screens all the time, so the newer the camera the better the monitor. However, there are some problems which the designers have yet to overcome. Firstly, it is often very difficult to see the image on the screen in bright sunlight. Some manufacturers have incorporated automatic brightness adjustment to combat this, but with only limited success. The other problem is that backlit colour LCD screens are very energy hungry. In fact, it is these monitors that make digital cameras so heavy on batteries. There are a few technological breakthroughs which may improve things , such as OLED (organic light-emitting diode) screens, but these aren’t available yet. In the meantime, the higher the resolution of your monitor, the easier it will be to see if your picture is in focus. Generally, anything over 130,000 pixels is very good.
It is a sad fact that most digital camera manufacturers seem to think that we only ever take photos in bright daylight with the sun over our shoulder. As a result, the built-in flashguns that most cameras come equipped with are extremely limited and virtually useless at anything over about ten feet. Unfortunately, only a few top-end digicams have the necessary hot-shoe or cable sockets to allow the attachment of more powerful flashguns, so you’ll just have to grin and bear it. When buying a camera, either check the flashgun guide number in the manual, or better still try out the flashgun in the shop. At least with a digicam you’ll be able to see the results straight away.