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Digital Camera Buying Guide:

Shopping for a digital camera can be a complicated and confusing process. For those without a good understanding of the technology, digital camera advertisements and specification sheets can seem like they are written in a foreign language. As technology continues to advance, the situation only gets worse.

This article will attempt to cut though the advertising hype and explain which features are really useful and which are not. Some features which are essential for one person, however, may be unnecessary for someone else. Ultimately, the decision making process boils down to choosing a product that is fits your needs. What camera is right for you depends a lot on your shooting style, and even more, on what you intend to do with your photos once you have captured them. This article is divided into several sections, each dealing with different features found on most modern digital cameras. The material provided here should help you decide what you need and what you don't.

How Many Megapixels do I Need?

The first thing most people consider when looking at a digital camera model is its megapixel count (MP). The megapixel rating actually refers to the number of pixels present on the camera’s sensor (a 6MP camera has a sensor with approximately 6 million pixels). The resolution of the sensor is directly proportional to the size of the resulting image in pixels. For example, a 4MP sensor could produce an image of about 2300x1730 pixels.

Most printers have an optimum resolution, which is around 300 pixels per inch or PPI. Don't be confused by printer manufactures advertising dots per inch (DPI) resolutions like 720, 1440 or more, as this refers to actual ink dots and not pixel resolution. The terms PPI and DPI are often used interchangeably leading to a great deal of misunderstanding.

The ideal resolution for most printers is usually somewhere between 260 to 300 PPI. If you are allowing your printer to do scaling, when an image is sent to the printer with slightly more or less than the ideal resolution, it will be adjusted accordingly. If you print and image with significantly more or less resolution than the ideal, the print quality may suffer as a result. The following chart gives a rough approximation of how many megapixels you need for prints of different sizes. The number of megapixels has been rounded off to even numbers:

Number of Megapixels Needed for Printing:
Print Size Good Quality - 200 PPI
Best Quality - 300 PPI
web photo 1 MP 1 MP
4x6 inch 1 MP 2 MP
5x7 inch 2 MP 3 MP
8x10 inch 3 MP 7 MP
11x14 inch 6 MP 13 MP
16x20 inch 13 MP 32 mp

Keep in mind that if you get a camera with more megapixels than you actually need, you can always downsize, and print smaller than optimal with a minimal loss of quality, however up-sizing, or printing beyond the ideal size will result in a more sever quality loss. The larger you go beyond the limit, the greater the loss of quality will be.

Another point to remember is that if you take photos at high resolution, the extra pixels present will allow you to crop out portions of the image you don't want and still have enough pixels left for a decent sized print. This gives the photographer a lot of flexibility for digital editing, but the higher the resolution of the image the more space it will take up on your memory card.

Lens Choices: Zoom or Fixed Focal Length?

Lenses come in two types: zooms and fixed focal length. A fixed lens, also called a prime lens, has only one focal length. This basically means that the field of view which the cameras sensor ‘sees’ (or the level of magnification) remains constant. If you wish to change the field of view with a fixed focal length lens-equipped camera, you must physically move the camera closer or farther away from the subject. If you are taking a photo of something nearby, like a portrait shot of a person, this only involves taking a few steps. It the subject is farther away, like a distant mountain, this could mean quite a hike. Freedom of movement may sometimes be restricted by obstacles like fences or rivers. These latter situations are where a zoom becomes handy.

A fixed focal length lens with a fast F2.8 aperture

A zoom uses moving lens elements to change the focal length of a lens, so physically relocating the camera is not necessary. In situations where movement is restricted, or for far away subjects, a zoom can be very convenient, and the greater the zoom range, or power, the greater the convenience.

A 3x zoom lens on a compact digital camera

As is usually the case, you don't get something for nothing, and zooms have a number of disadvantages when compared to fixed focal length lenses.

The first and most obvious disadvantage of a zoom is its bulk. A zoom will add both size and weight to a camera; how much size and weight it adds depends on its design and on the zoom range (2X, 3X, 4X…). Generally, a zoom with a greater range will be bigger and, all things being equal, have a lower optical quality. The zooms found in most modern compact cameras are reasonable small and their convenience can outweigh the increase in bulk they add.

A large but bulky higher quality 3.2x zoom lens

A camera equipped with a zoom is not only bigger however, it is also significantly more expensive. The added lens elements, and the motor to drive them, all add to the production cost. If you are on a tight budget, a fixed focal length camera can be a good option. In most instances, you can just move to get a better vantage point, though you may miss the odd shot that a zoom would have allowed you to capture.

Another disadvantage of a zoom is the aperture size. Zooms have a higher f-number value, which means less light can reach the sensor when shooting with a wide open aperture setting. This means that in certain low light conditions, a camera with a zoom will be unable to take a sharp photo whereas one with a fixed focal length lens would. This disadvantage is often offset by the fact that most cameras come equipped with a built-in flash. The flash can provide the additional light which is needed for a correctly exposed photo using a high enough shutter speed to take a sharp image. There will always be some situations, however, where a flash cannot be used, either because it is not powerful enough (like for shooting outdoors at night when the subject is beyond flash range), or because it is not allowed (like in some museums or art galleries). In these instances, a fixed focal length camera would have an advantage and a zoom camera might need a higher ISO setting or require a tripod to take a sharp picture, depending on how much light is available. Keep in mind though, that if light levels are very low, even a camera with a fixed focal length and low f-number like F2.8 will not be able to cope.

Digital Zooms: When is a Zoom not a Zoom?

When comparing the advertised specifications for digital cameras, you will often come across terms like: digital zoom, optical zoom and combined zoom values. It is essential to understand what these terms mean if you intend to make an informed buying decision. Magnification which is achieved though physical movement of the lenses elements (this is what we have been discussing up to this point) is know as optical zooming. Most cameras also have a digital zoom feature which supposedly extends an optical zooms range; for example, a camera my have a 3 times optical zoom and a 2 time digital zoom for a combined 6 times zoom factor. There are digital zooms of even greater magnification and what is more, the do not add weight, size or cost to a camera. This might sounds too good to be true, and of course, it is. The digital zoom feature is nothing more than a marketing ploy; it looks attractive on paper, but provides little to no real value. A digital zoom is software-based feature that lets you select a smaller, central portion of the cameras sensor. Since only part of the sensor is being used to take the picture, a digitally zoomed image will contain less pixels. This is because the number of pixels in the photo is proportional to the number which the sensor has (a 4 MP camera can be digitally zoomed in to use only the central 2 MP of the sensor). When the picture is displayed on the tiny LCD camera screen it will appear to have been zoomed in and will have been enlarged fill the whole screen. If however, the image is viewed at full size (100% magnification) on a computer monitor, it will be significantly smaller and the lack of pixels will mean it cannot be printed at as large a size. A digital zoom is in fact nothing more than an in-camera cropping too. It cuts the edges off the image, but the resulting file is smaller as a result. If you wish to crop your photos, this is much more easily done with your favorite photo-editing program.

Digital Memory Cards for Data Storage

With the advent of the digital format for image capture, it was necessary to develop a method for storing data. The earliest digital cameras had small hard drives. The earliest hard drives were relatively large and of low capacity. As digital cameras gained popularity, a large number of flash memory card formats were introduced, as well as a super-compact Microdrive hard disc. Most of these formats are still with us, and in fact, new formats have since been introduced, further adding to the confusion. For a discussion of these various formats see the article Guild to Digital Memory Card Formats on this site.

Compact Flash digital memory card

When choosing a camera, it is important to be aware of what format or formats of memory card the camera can accept. Certain camera manufactures like Sony, only support one format, which can be inconvenient if you have more than one camera or if you own other portable devices from different manufactures and wish to share your memory cards. Ideally, it would be best if there was only one format which was compatible with all devices. If you choose a camera which supports one of the more popular formats such as Secure Digital (SD) or Compact Flash (CF), you are more likely to be able to use them in a greater variety of devices; SD for example, is used in a lot of portable electronics like Global Positioning Systems (GPS), MP3 players and some laptop computers. If you select one of the more popular formats you are also less likely to be stuck with useless obsolete cards that you cannot use on future camera models.

Digital Camera LCD Screens: Reviewing and Previewing your Photos

With all the hype concerning megapixels and zooms, people often overlook other features. When comparing models, don't forget to evaluate the camera’s LCD display screen. It's best if you can do a hands-on comparison in the store. Screens vary in both size and quality. A larger, better screen can let you see your pictures more clearly, both as you are taking them, and after the fact; this can actually help you save memory card space. With a good screen, you can zoom in on photo you have taken, and choose to keep only the sharply focused, correctly exposed images. Deleting unsuccessful shots allows you to make more space available. The better and bigger the screen, the easier this weeding out process will be. Keep in mind though, that a bigger screen may use more batteries than a smaller one.

A flip-out rotating LCD screen

Many new cameras have screens in the 1.8 inch to 2.0 inch range, and a few have even larger ones. Some older models have screens as small as 1.4 inches. It can be quite difficult to view your pictures on such a small screen, even with magnification. If your eyesight is not very sharp or you are prone to eye strain, it would be a good idea to get as large a screen as possible and just live with the increased battery drain (you can always purchase a spare battery or two to bring along if you go for extended shooting sessions).

While size is important, it is not the only consideration. When doing a specification comparison, also check the number of pixels the screen has (the screen’s resolution). Resolution can influence the way the image is displayed in a number of ways. Generally, for LCD screens, more is better.

Another feature of some LCD screens is the ability to swing out and rotate. This can be handy in certain situations. If you have to lift the camera above and obstacle, you can rotate the angle of the screen so you can still see the preview. Similarly, if you need to position the camera very low to the ground, like for a macro shot, you can tilt the screen up for easy viewing. This feature is not available on the more compact digital cameras, so if you need it, you will have to shop for a mid to large-sized model.

Image Stabilization Technology

Image stabilization is a technology that is not being introduced into point-and-shoot digital cameras. This is not a new technology-it has been used in SLR lenses and binoculars for many years, but it is a relatively recent feature addition for point-and-shoot digitals. This technology uses tiny motors inside the lens to help compensate for camera movement caused by unsteady hands. A sensor in the camera detects motion and the motors compensate for it by moving special lens elements. No matter how steady you are, you cannot hand hold a camera and remain perfectly motionless (this is why we need tripods), but image stabilization will help keep the keep the picture steady for you. What all this means is that you can shoot with a slower shutter speed, therefore you can take pictures in lower light conditions without the need for a flash. At present, only a few models have image stabilization, and it can add quite significantly to the cost of a camera.

A image stabilization equipped digital camera

All text and images © Copyright Alex Leveson. All rights reserved.
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