Shutterbug with Greg Rothschild

Help! I Need to Buy a Digital Camera!

That's a post seen frequently in the photography forum. Camera shopping presents a big challenge to those not familiar with photography's technical aspects. Not only does it present a daunting new and foreign language full of unfamiliar terms such as f-stop, megapixel and white balance, but it also requires spending a good chunk of change; it's enough to send anybody to the medicine cabinet for some headache medicine. Making the best choice simply requires a little education. Learning what some of those terms mean will help you make a good selection, while at the same time improving your photography.

Another big decision to be made is where to buy the camera - we'll go over some tips to help with that decision too. And finally, we'll discuss some accessories you might want to purchase to help get the most out of any new camera.

Understanding Some Commonly Used Terms:

One of the first terms encountered when shopping for a digital camera is megapixel. Pixel is a contraction of the words "picture" and "element," by the way (and mega is just the Latin prefix meaning "millions"). Think of a pixel as a tiny dot which, when combined with millions of others, forms a photograph. Resolution is another commonly seen term - to calculate a camera's resolution, simply multiply the number of horizontal pixels by the number of vertical pixels; the product is its resolution, also referred to as megapixel rating.

How many megapixels are necessary? To answer that question first determine how big you want to make your prints. This is the main consideration for determining what resolution camera to buy. Most 4 megapixel cameras are easily capable of producing high quality 8" x 10" or even 11" x 14" prints, which are plenty big enough for most of us. Remember, once a print is matted and framed, a typical 8" x 10" print will take up a lot of wall space. If of the goal is to print poster-sized prints and hang them all over the house, then look into 8mp cameras, but beware! All sensors are not created equal. The number of megapixels is not the only determinant of image quality. By packing the pixels very densely manufacturers have, in some cases, achieved a high pixel count, but at a cost of increased digital noise. Think of digital noise as "graininess." To avoid this, look at sample images from each camera before buying - especially shots taken at 400 and 800 ISO.

Next to the image sensor, the lens is the camera's most important part. This leads to a description of a pair of phrases most prospective buyers have probably seen and wondered about: optical and digital zoom. "Zoom" refers to the variable focal length of this type of lens. It has a wide end and a long, or telephoto, end. The wide end is where the lens is zoomed all the way out and sees its largest field of view. That end is used for landscape or whole tank (or even tank room) images, and fits into the picture as much as possible of what the eyes see. The long end of the lens is used to bring the subject closer so that it appears in the frame bigger than it seems to the eyes. In effect, the lens actually magnifies the image.

Digital zoom occurs within the camera's electronics - the image's center is merely cropped and enlarged to achieve greater magnification. This image enlargement always introduces some degradation, so it's recommended to use this feature as little as possible. Remember, digitally zooming is a poor substitute for poor framing of the subject. If the image is out-of-focus, digitally zooming it will give a nicely enlarged out-of-focus image, and should really only be used when there is no alternative. Most cameras' digital zoom feature works in steps. Often the first step gives decent quality; after that, however, things go south quickly, so using that feature is not recommended except in extreme circumstances. For instance, if Bigfoot is spotted attacking a Grizzly down by the riverside, by all means, zoom, zoom, zoom!

Optical zoom describes how the glass elements inside the lens physically move to magnify the image. Lenses are specifically and carefully designed to do this, and since they do it without cropping and enlarging, it does not diminish the pictures' quality. Manufacturers list the optical and digital zooms with an x factor, which simply refers to the difference between the lens' wide and long ends. For example, a 20-100mm zoom lens has a 5x optical zoom because 20 goes into 100 five times. This illustrates why the optical zoom number, by itself, has little meaning, because it doesn't tell how wide or long the lens is! The lens' focal length must be known also, in order to understand how the it will perform.

As I mentioned, the wide end of the lens is good for landscape (e.g., whole tank, full tank room) shots, while the long/telephoto end is good for shots of individual fish or corals. Below are some examples of images taken at various focal lengths, to give an idea of what can be fit into the frame using the wide end of the lens, and how close-up the shot can be with the long end.

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A wide shot, approximately 20mm.
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A medium shot, approximately 50mm.
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A tight shot, approximately 100mm.

A previous article went into some detail about what white balance is and how to get accurate colors in aquarium photos. What white balance features are important in a camera used for aquarium photography? Because of the extreme (in terms of color temperature) lighting over fish and reef tanks, any given camera may have difficulty giving accurate colors via its automatic white balance setting, so the ability to set the white balance manually is crucial. Aside from that, most cameras offer a wide variety of preset white balance options such as sunlight, incandescent lighting, flash, cloudy day and fluorescent, so they should be fine for all other types of standard photography. Some cameras give the user the ability to fine-tune the white balance. This is a handy feature that allows for small adjustments to whatever white balance setting the camera has chosen. Finally, some cameras have an option for setting the white balance by color temperature. If the bulbs' color temperature is known, this can be a very useful tool.

Most, but not all, cameras have the ability to be focused manually. Manual focus can be very helpful for close-ups because autofocus, on even the best cameras, sometimes has difficulty focusing on close subjects, especially if the subject has little or no contrast and texture. While manual focus should not be a deal breaker, it is a nice feature to look for. A useful trick for those times when the lens is struggling for the right focus is to aim the camera at a nearby subject that has good contrast, hold the shutter button halfway down to focus on that, then while keeping the shutter button depressed halfway, recompose the shot on the original subject, using the LCD to make sure the shot is focused at the correct distance.

Macro focus range is another term used in camera specs. This term refers to how close the camera can be to a subject and still keep it in focus. The closer this is, the greater the magnification, and high magnification is the goal for close-ups. But this magnification equation has two sides. One is how close the camera can focus, and the other is the focal length of the lens (how far it can zoom in); the longer the lens (the more it can zoom in) and the closer the focus, the better the photo. So look for a lens that is the best compromise for the intended types of shots.

It's Time to Shop!

Where to buy a camera? So many choices… this is where the internet really shines. Shopping on the internet has made us all more informed consumers - we can compare prices from dozens of stores with a click or two of the mouse. Sources include websites such as,,,, etc. ad infinitum. It's likely that once a decision on what camera to buy has finally been made, the price will seem too good to be true. Sad to say, but it probably will be too good to be true - many less than forthright dealers out there are willing to take advantage of the trusting consumer. The best piece of advice for checking up on dealers is to look them up on before buying.

One of the tricks shady dealers use is to list the camera at an extremely low price, then sell accessories at inflated prices. Another common ploy is to sell a gray market camera without informing the consumer. Gray market equipment comes from overseas with no U.S. warranty, so beware! Downright dirty dealers will even open the factory sealed camera package and remove necessary accessories, such as the battery and battery charger, and then try to sell them as separate items.

B&H has been around a long time and has traditionally been the standard for good prices. They don't have the most rock-bottom prices but they are a great site to check first, partly because their prices are low and partly because they are the biggest in the business. They also are known to be among the most reliable.

The first accessory to consider purchasing is a tripod. Use one and become a better photographer-it's as simple as that. Of course it steadies the shots, but it also requires more attention to the composition of the shot, since it allows additional time for critical inspection of the frame. Sometimes using a tripod is absolutely necessary - certain shots are impossible without it. To better understand why tripods are necessary, refer to the section of this article in the November 2004 issue of Reefkeeping Magazine, which discusses depth of field.

Close-up filters are commonly used to improve a camera's macro performance. These filters work just like a magnifying glass, in some cases decreasing the working distance between lens and subject, effectively increasing the lens' magnification substantially. Hoya and Tiffen and some other companies make fairly inexpensive sets of close-up filters, sometimes called diopters. The optical quality of these filters is fair - neither great nor horrible. They are an inexpensive way to improve a camera's capabilities. Other companies, such as Canon and Nikon, make two element filters that are of excellent optical quality. They cost a little more but are worthwhile options.

A back-up battery and an extra memory card are accessories that everyone should have in his camera bag. Again, refer to before buying these accessories. Memory cards come with speed ratings - is the fastest card available necessary? The answer most likely is no. Speed ratings are listed with an "x" number that tells how fast the data is processed in the camera. Each "x" is 150KB per second, so a 40x card will process data at approximately 6MB per second. Most cameras cannot match that speed, which is why it's not necessary to buy the latest, greatest memory card. Refer to the specs in the documentation that comes with the camera to see how quickly it processes data. In most cases a super fast card is overkill. Where speed does come in handy is when transferring images to a computer, assuming the use of a USB2 card reader. If the camera itself is transferring the photos (via direct connection to the computer), then the extra speed won't be realized.

One last suggestion before you go out and buy your new toy: try to read as many reviews as possible, and look at sample pictures from the cameras you are considering. The internet has many great review sites, with unbiased and thorough reviews. The site that I refer to most often is

Best of luck in your shopping!

If you have any questions about this article, please visit my author forum on Reef Central.

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Help! I Need to Buy a Digital Camera! by Greg Rothschild -