It's a poor carpenter who blames hir tools. This is also true for digital photographers. However, this is no denying that cameras that offer advanced photographic options enable you to fine-tune focus, exposure, and color with more precision than a basic one. In the following part of this article, I will bring to your attention a few issues that may not occur to you when you're shopping but play a big role in your long-term satisfaction with a camera.

Manual exposure control

Three camera components affect exposure:

Aperture

The aperture is an tiny "hole" in the lens that controls how much light enters through the lens. Aperture size is represented by f-numbers such as f/2.8. The higher the f-number, the smaller the aperture size and the less light enters through the lens.

Shutter speed

The shutter is like a door behind the camera lens. When you take a photo, the shutter opens to allow light to enter through the lens and strike the camera's image sensor. Therefore, the slower the shutter speed, the more light the sensor get.

ISO

This is used to indicate the light sensitivity of the image sensor. The higher the ISO number, the more sensitive the image sensor and the light is required to expose the image.

Manual exposure control does not only gives you the ability to control how light or dark your photo appears. What's more, aperture affects depth of field, while shutter speed determines whether a moving object blurred or not.

Besides the program (P) mode, in which the camera chooses the aperture size and shutter speed automatically, advanced cameras also offer you the manual (M) mode, in which you make the decisions yourself. Plus, many cameras offer aperture-priority (A) mode and shutter-priority (S) mode, in either of which, you select one control (aperture size or shutter speed) and the camera calculate the other automatically. Not only does working with a camera that offers PASM modes give you the opportunity to implement your creative decisions, but also enables you to manually deal with some difficult conditions under which automatic exposure cannot handle.

In my opinion, you don't need to pay much attention to ISO ratings. At high ISO ratings, photos are usually full of noises.

Focal length

Focal length, which is measured in millimeters, is the distance between the optical center of the lens and the image sensor. It affects the angle of view and the size at which your objects appear. At a short focal length, you can capture a wide aera, but objects appear smaller and farther away, while at a long focal length, the opposite is true.

In most conditions, you can't evaluate digital camera focal lengths on the same scale you use for a traditional camera lens. This is a bit complicated to explain fully, but I can give an oversimplified explanation here: The size of the recording element affects what the camera sees at a particular focal length, and in most cases image sensors are much smaller than the traditional 35mm film negatives.

Because photographers are more familiar with the focal lengths of 35mm film and a variety of sensor sizes are used in digital cameras, the digital industry has adopted the practice of staing camera focal lengths as 35mm film equivalents.

So digital camera specs may read something like this: "Focal length: 5.8 mm, equivalent to 35mm with 35mm film." This tells you that the digital camera lens produces the same image you would get with a 50mm lens if you were shooting 35mm film. Note that I use the word same in the meaning that the same angle of view. The optical effect is different because of the difference of the size of the recording element.

Some basic guidelines for focal lengths:

• A lens with a focal length equivalency of less than 35mm is considered a wide-angle lens. Wide-angle lenses are perfect for landscape photography.
• A focal length equivalency of 50mm produces the most natural view, recording a subject at approximately the same size and distance as your eyes see it.
• A focal length equivalency of more than 85mm is considered as a telephoto lens. You can use them to capture a distant object in a close view.

A zoom lens enables you to shift between a range of focal lengths. If you want to buy a digital camera, just ignore what-so-called digital zoom. This feature is nonsense. Roughly speaking, digital zoom is enlarging your photos by reducing the quality.

Also, don't get confused with things like "4x optical zoom". For example, one camera's focal length range is 17mm to 85mm, and another's is 70mm to 200mm. The first camera is a 5x optical zoom camera (85/17=5) and the latter is a approximatively 3x optical zoom camera (200/70≈3). But obviously the second one has a much large focal length range than the first one.

To sum up, when buying a digital camera, just ignore digital focal lengths, digital zoom and optical zoom, and look for the 35mm equivalency numbers.

Manual focusing mechanisms

Besides autofocus, advanced digital cameras also offer manual focusing.

Pixels

Roughly speaking, more pixels means more details. However, unless you are buying a DSLR, don't lay much emphasis on pixels. At the time I wrote this article (2007), all most every main-stream digital camera manufacturer doesn't offer models below 500 million pixels. This is enough for a beginner. And general speaking, given the certain sensor size (for consideration of portability and cost-saving, manufacturers usually won't enlarge the image sensor at the same time), more pixels tend to cause more noises.

Image format

All digital cameras provide the JPEG format, but advanced models also provide TIFF format or RAW format. TIFF format is wildly used in professional field and is better than JPEG in quality. And RAW format, which is not a real image format, strictly speaking, is actually the raw data the image sensor recorded. Therefore, it provide ultimately flexibility in the digital darkroom stage. Both TIFF and RAW need much more storage space than JPEG. From my viewpoint, it's a good idea to get a camera which support RAW format if you are a serious photographer. And I don't prefer TIFF cause it requires a bit more storage space than the RAW format and lacks the flexibility.

Viewfinder

Some digital cameras do not offer a viewfinder, forcing you to use the LCD monitor solely. I don't recommend this choice. This is not only because the batteries' life get shorter when the monitor is turned on all the time, but also because the displays on most monitors tend to wash out in bright sunlight. For the same reason, I don't think a large LCD monitor makes much sense.

Note that some cameras provide electronic viewfinders instead. When you look through it, you see whatever the lens is looking at plus all the information normally displayed on the LCD monitor. A electronic viewfinder is more convenient than a traditional one. However, it consumes battery power.

Tripod mount

In situations that call for a slow shutter speed, for example, take landscape photography at night, you need to mount your camera on a tripod. Almost all digital cameras include the necessary screw threads for attaching the camera to a tripod. However, some extraordinary slim models don't provide this function. Be careful, a tripod mount is somehow essential.

Recording media

SD card is the main-stream recording media. Standing by the main-stream recording media means you have more choices of brands and usually get the same capacity at a lower price.

Batteries

AA-sized batteries are cheaper and available almost everywhere. However, they are heavier and bigger.

Control Accessibility

Last but absolutely not the lease, is the control accessibility. If you're forced to go through batches of menus and press many buttons to make your selection in most times, you're sure to get frustrating. What's more, you may miss the opportunity to take a shot when you're finding your way through those menus. Thus, if possible, look for a model that allows you to control regular functions via buttons or dials.

In the end

I never mean that you are ought to buy a camera which satisfies you at all the aspects I mentioned above. I didn't list portability and price, which is absolutely very important when choosing a camera. You may also have some specific needs, such as avoiding shake effect, waterproof, the ability to record movies, etc. I myself bought a Canon's A570 IS, which doesn't satisfy me in every aspect. However, for me, it's the best choice at its price level.