Excerpt: Take Control of Buying a Digital Camera

Editor’s Note: The following article is an excerpt from Take Control of Buying a Digital Camera, Third Edition, a $10 electronic book available for download from TidBITS Electronic Publishing. The 107-page ebook helps readers determine the best camera for their needs and provides a detailed guide to buying a digital camera with looks at the latest trends, camera models, and pricing. Special offer for Macworld.com readers—save 30 percent!

For the most part, the advice in Take Control of Buying a Digital Camera applies equally to digital single lens reflex (DSLR) and point-and-shoot cameras. But since DSLRs are inherently designed for advanced users, many trade-offs that you must choose between with point-and-shoot cameras do not exist in the same fashion as they do for DSLRs.

For example, no DSLR fits in your pocket. If you want quality, you get quality in spades, but you have to lug it around. Lens choices abound: zooms of all kinds, as well as super wide angles and big, fast sports/wildlife lenses. You have to lug those around, too. In other words, SLRs are for people who are willing to sacrifice convenience for quality.

Therefore, choosing a DSLR is less about camera model trade-offs and more about finding a total system that works the way you do. The DSLR camera body is just one part of an overall system of lenses, lights, other accessories, and computer hardware and software, making your research options more complicated.

This figure shows a huge cropped shot (this is about 5 percent of the original frame!) from the 8-megapixel Canon Digital Rebel XT and a 50mm Macro lens. DSLRs can use special lenses, and their image quality makes such sharp pictures possible.

The DSLR system

I recommend that you consider these important factors when choosing the camera hardware for a DSLR system:

• Are you willing to carry around the weight and bulk of a DSLR and its complement of lenses and other accessories? Are you willing to go out to shoot during the magic hours of sunrise and sunset when everyone else is kicking back at dinner or breakfast? Will your friends/spouse/partner let you go have fun while they cook?

• Does the DSLR fit your hands well? Do the controls naturally fall under your fingers, or do you have to contort your hands even a little to operate them? (If so, you will have ergonomic problems in the long run.) Better to choose the system that best fits your hands.

• Do elements of the DSLR system make sense to you? Specifically, do the control layouts and control menus make sense? Do the buttons make sense as you learn their layout and function, or do you find yourself thinking “I would have put it over there instead,” or “I would prefer a single button push instead of this design.” Do the menus give you rapid access to features you need, such as custom white balance mode or resolution settings? These, too, should make sense to you as you learn them.

• Does the DSLR camera body, the lenses, and other components of the system perform as advertised in the field ? Does the auto-focus reliably and consistently lock when engaged in various types of lighting conditions with moving subjects? Does the camera’s automatic exposure meter make consistent (not necessarily accurate) readings in varying light? Does the camera make accurate exposures with the system’s speedlites? Does the automatic white balance work well indoors as well as outdoors? Does the custom white balance function well when the automatic system does not? Do the batteries hold up in cold weather? Are the lenses well designed and well made? Is the body weather and dust resistant?

• Can you actually see fine detail in the optical viewfinder? Some people have described the image seen through DSLR viewfinders as like “looking at a postage stamp at the end of a dark tunnel.” To keep costs down, DSLRs have smaller mirror/prism assemblies than their film counterparts. Thus, you can’t always quite tell if you got what you wanted until after you download your pictures or preview them on the LCD screen. Finer details can be missed because the image in the camera viewfinder is simply too small. This is important if you photograph people’s expressions, for example. Unfortunately, most low-cost DSLRs suffer in this area.

• Does the system’s workflow enable you to use the histogram and overexposure warning signal quickly and effortlessly? For digital photography at this level, histograms and overexposure warnings are more than features—they’re necessities.

• Due to the use of certain image sensors and proprietary image processing systems, each manufacturer’s DSLR family has a recognizable “look.” As with point-and-shoots, the settings are adjustable, but do you like the overall color palettes offered by a camera family? Is this even important to you?

• Is the manufacturer’s hardware on the leading edge of digital imaging technology, or is it just keeping pace with the competition? This distinction matters because once you begin acquiring lenses and other special equipment for a given system, you tend to stay with that system; switching from one to another is time-consuming and costly.

• What is the field-of-view cropping factor? (See Lens Focal Length Options.) How does that affect your lens selection?

• DSLR models usually work best with a specific brand of memory card. The reasoning is beyond the scope of this guide, but what it means for you is additional research and expense to discover and purchase the better-performing memory cards that “mate” better with your chosen DSLR. See Rob Galbraith’s Web site for his CompactFlash (CF) database. Note that you needn’t buy a top-of-the line pro memory card if it gives you only a few more bits of data per second.

• DSLRs are highly specialized computers, and they are subject to the same rapid depreciation as computers and other electronics. Is it worth spending $1,500 or $4,500 or $8,000 on something that will be upstaged by a significantly improved model in 18 months?

Prices and resolution

After comparing systems, choose your price point (and don’t forget that you aren’t buying only a camera body; you need lenses and other accessories too). I believe strongly that a system’s usability is in many ways more important than the number of megapixels built into the camera’s sensor. Nonetheless, we are always comparing our cameras by the megapixel yardstick, and who wants the best camera design in the world if it only has a 3-megapixel sensor? Just remember to ask yourself, “How much is enough?” At present, DSLR models hit the price points and resolutions shown below.

In discussing megapixels earlier, I said an 8-megapixel DSLR is likely to be superior to an 8-megapixel point-and-shoot. Here’s why: the megapixel number comes from the number of pixels on the image sensor chip. However, any DSLR chip is physically larger than a point-and-shoot chip because the DSLR must accommodate the larger size of the image projected by DSLR lenses. Practically speaking, a large physical pixel produces a cleaner (less noisy) signal than a physically smaller pixel (all else being equal). Thus, DSLRs should provide for much cleaner image data than a comparably sized point-and-shoot, especially at higher ISO settings. While I cannot predict how much you will want to spend, I suggest that the upper low-end models (up to $1,500) are the best value, because they combine high image quality with superior usability and other features that all but the most demanding pros and hobbyists will need.

As a matter of fact, for most publications today, pictures made with any 6- to 8-megapixel model is more than adequate for print reproduction. They are also adequate for making enlargements and printing up to 11 x 17 inches and beyond, depending on the image and the Photoshop techniques used to enlarge them.

Pros and advanced hobbyists use the higher priced models for three primary reasons: speed, usability, and reliability (e.g., superior autofocus speed, autofocus tracking, viewfinder black-out time, color, contrast, workflow, weather-sealing). In many small ways that add up to big differences, the $4,000 cameras are superior to the lower priced models; for some photographers, these machines are considered “entry-level.” Sports and wildlife photographers in particular push the technology to its limits in their quest for unique images.

The $8,000 model attracts commercial advertising pros and fine art photographers seeking the state of the art. When absolute resolution and massive file size are more desirable than speed, the top of the line is it. Clearly, you can make a pretty big print with so much data.

Lens focal length options

The great advantage of the SLR design is the capability to use interchangeable lenses. Some manufacturers offer dozens of lenses to choose from for all kinds of purposes. However, most of these lenses were designed for use with 35mm film cameras.

A significant issue to consider with DSLRs is the focal length magnification factor , also known as the cropping factor or field-of-view cropping factor . DSLRs are designed to work with film camera lenses, but since 35mm film is larger than most image sensors made today, most DSLRs can record only a portion of a lens’s field of view. This portion is seen by the viewer as a cropping of the image and effectively makes film SLR lenses appear longer—more telephoto&38212;than they were designed to be. This effect can be problematic when choosing lenses. (The exception is Olympus’s 4/3 system, currently manufactured only by Olympus. These cameras have no cropping factor issues, but do have an inherently smaller sensor design.)

This magnification factor is 1.5x to 1.6x on many lower priced DSLRs. What this means is that just like point-and-shoots, you sometimes must use a focal-length conversion to compare lenses. For example, a wide-angle 24mm lens originally designed for film cameras would effectively become a 38.4mm lens (24mm multiplied by 1.6) when used with a 1.6 factor DSLR. It’s worth noting that 38mm is not particularly wide-angle. In other words, to get 24mm wide-angle focal length on a DSLR requires a 15mm lens (15mm multiplied by 1.6 equals 24mm). However, these super-wide-angle film SLR lenses are expensive. Fortunately, affordably priced lenses designed specifically to address this issue are now available from major manufacturers.

Tip: A great advantages of digital capture is that scanning film introduces noise to the image data, which is amplified when enlarging the image in software. With digital capture, you can successfully enlarge digital camera captures far beyond what you can with film. Now you can make a poster of that once-in-a-lifetime shot!

Some mid-range DSLR models offer lesser magnification factors of 1.3x, and the latest top-of-the line Canon (the $8,000 Canon 1Ds Mark II ) has no magnification factor—it is a full-frame sensor. This is good news for people who already own a large selection of film SLR lenses and are in the market for the state of the art. Canon broke new ground in October 2005 with another full-frame model, the EOS 5D for $3,300 . With this in mind, the table below takes our price and megapixel table from earlier and incorporates lens-cropping data.

DSLR dust spots

Other than bulk, complexity, weight, and attractiveness to thieves, a major problem with interchangeable (removable) DSLR lenses is dust settling on the image sensor. You can see the effects in the screenshot below.

Changing a DSLR lens can cause dust to settle on the image sensor. Dust appears in your images as shown above, circled in red. In this example, the dust spots are larger than they would normally appear because the frame above is cropped from the full frame.

Dust requires you to clean the sensor surface by using a rubber squeeze blower (do not use compressed air!) or by purchasing special brushes or swabs from companies such as VisibleDust. Some newer DSLRs have self-cleaning sensor technology built into the camera body. This may become standard on future models.

Warning: When cleaning the sensor, follow your camera’s instructions found in the owner’s manual. Significant damage may occur if you don’t follow the manufacturer’s recommendations.

As with anything, you need to clean and care for your equipment, but it can be a drag if you have only one DSLR body and like to change lenses often outdoors. You don’t have to be on safari to encounter dust or rain. Soccer fields, construction sites, hiking trails, and anywhere it rains or snows can adversely affect your camera and lenses.

Tip: Turn your DSLR off when changing lenses; the electrical charge on the sensor attracts more dust when powered on.

DSLR computer workflow

Just as with point-and-shoots, plenty of back-end software is available to manage the digital creations captured by your DSLR. But again, because DSLRs appeal to artistic photographers who want to take full control of the images they create, the software used for snapshots may not offer the control you’re looking for. DSLR workflow can be much more complicated. Workflow entails not only how you transfer the image file from your camera to a computer, but also how you adjust your image or use it with others, and how you store or archive your digital shoebox. In other words, the digital file straight from the camera may only be an intermediate step in the “development” process. The photographer may still need to make adjustments to color, contrast, cropping, etc. This reality appeals to some and frustrates others.

Many books, classes, and seminars are offered on this subject, which goes far beyond what I can offer in this excerpt (or even the full book). Start researching by checking periodicals and Web sites that speak to the style of photography you’re interested in. You will learn more from others who share your photographic interests than if you were to just sign up anywhere to get hit over the head with computer books!

Hordes of photographers tend to swear by their favorite systems and denigrate others. Along with politics and religion, SLR systems bring out the inner fanatic in otherwise normal humans. Weigh their opinions and remember that your preferences, not theirs, matter most.

[ Laurence Chen is a professional photographer and adjunct faculty member teaching photography at Seattle Pacific University. His work has appeared in the New York Times, Sunset Magazine, America 24/7, and many other places; his latest book is Take Control of Buying a Digital Camera, Third Edition (TidBITS Electronic Publishing, 2006).]