Want to buy a Digital SLR?
Here are our digital SLR expert's answers to the most important questions
By Arthur Bleich
Thinking of buying a Digital SLR with that spare thousand bucks you have hanging around? Here are the top 15 questions I get asked from readers who want to choose wisely. Only cameras that have interchangeable lenses and through-the-lens (non-electronic) viewing are covered here. Read on and pick a camera that's best for your needs.
What is a dSLR?
It's an acronym for "digital single lens reflex" camera. Film SLR cameras have been around for a long time. By using mirrors and prisms, they allow you to preview and compose your image through whatever lens you happen to have attached to the camera. You see just what the lens will see; in fact, it's like looking at a finished print of your image. When you're ready to capture the picture, an internal mirror swings out of the way to let the light hit the camera's sensor, the exposure is made, and the mirror swings back down again to let you continue viewing. All of this happens in a fraction of a second so you hardly notice it.
Why are dSLRs desirable?
The camera virtually becomes a part of your eye. You don't have to squint through an optical viewfinder which usually shows you less than the lens actually covers. And it's not necessary to hold the camera away from you to view an LCD monitor--an unstable way to hold a camera and also prone to being washed out by bright sunlight. When you view your image with a dSLR, there are no outside distractions--it's like looking at a movie in a darkened theatre. Furthermore, while the ability to switch lenses isn't limited to dSLRs, there are only a couple of non-dSLRs that offer this feature and, of course, you cannot preview your images through lenses made for these cameras.
They look big and heavy. Why?
Professional dSLRs are big and heavy because they have to take a lot of physical abuse--that's the difference between a truly professional workhorse and the prosumer cameras (consumer cameras with professional features) we're talking about here. It's like the difference between a HumVee and a Hummer--one's built for war and the other's not. Since you won't be shooting hundreds of pictures every day or using your camera in hurricanes or wars, you don't need a reinforced metal body, overbuilt internal parts or "O" rings. Compared to their big pro brothers, prosumer dSLRs are relatively small and light (though not pocket-sized, obviously) and there's no difference in the picture quality between the two.
CCD? CMOS? What's the difference?
Most dSLRs in the under-a-grand category use CCD (charge-coupled device) sensors; only Canon uses a CMOS (complementary metal oxide semiconductor) sensor. CMOS uses less power, is easier and less expensive to manufacture, and Canon claims it produces fewer artifacts than CCDs, allowing them to use greater image compression which results in a greater number of pictures that can be stored on a memory card. In terms of image quality, CCD and CMOS are equal.
Why are sensor sizes on dSLRs different?
They're different because there are no standards. Actually, even the size of a 35mm film frame varied on different cameras until the 1950s. The dSLR cameras in the category we're discussing have sensors that are smaller than a full 35mm frame, reducing the costs involved in producing them. Despite differences in physical sizes, all except Olympus keep the 35mm picture proportion (2 x 3). Olympus uses a 4 x 5.3 proportion which allows 5x7, 8x10, and 11 x 14 prints to be made with less cropping. Regardless of differences in sensor size and proportion, all dSLRs produce excellent pictures.
What's a "multiplication factor"?
This is tied in to the size of the camera's sensor and you multiply the focal length of the lens you're using by it to give you its angle of view, were it being used on a 35mm film camera. Since 35mm film cameras have been around for more than 70 years, most photographers are more familiar with the approximate angle of view that 35mm lenses cover. A 28mm lens on a 35mm camera is a moderately wide angle lens, but when used on a dSLR with a smaller-than-35mm sensor size, its angle of view becomes smaller. Multiplication factors on Nikon, Pentax, and Minolta cameras are 1.5, Canon, 1.6, and Olympus 2.0. So an 18mm lens (18 x 1.5 = 27) on the first three takes in the same angle of view as a 27mm lens on a 35mm camera. On a Canon, it would be 29mm, and on an Olympus, 36mm. However, Olympus designs wider angle lenses for their dSLRs, so it all evens out. Their 14mm is the equivalent of 28mm on a 35mm camera.
Can my 35mm lenses be used on dSLRs?
In most cases, yes. In fact, if you already have Nikon, Pentax, Minolta or Canon lenses, your dSLR decision will most likely be to get the same brand of camera. Most lenses are backward-compatible and will work just fine. Because of the multiplication factor, they will take in a narrower angle of view shifting more into the telephoto range. This is not a problem if you shoot portraits, wildlife or sports but it can be more restrictive if you like to use wide-angle lenses for landscapes or photojournalism. There used to be a dearth of wide-angle lenses for dSLRs but that's been remedied lately. Incidentally, you can also use older Olympus lenses but you must use a lens mount adapter and, except for limited automatic light metering, the lenses will not retain their automatic functions. You must focus and stop down the lenses manually.
Are digital and film lenses different?
Lenses made specifically for digital cameras are usually smaller and lighter and are designed to cover the area of the smaller sensor. In other words, if you used them on a 35mm film camera, the image would be vignetted--dark at the corners. They are also are designed to bend light rays so they hit the sensor more or less straight on which, manufacturers say, results in a better image. In actuality, 35mm film lenses can produce equally good results because they cover a much larger area than the sensor and use only the center of the lens--the so-called "sweet-spot"--to produce images. Don't pass up a good deal on a film lens, especially telephotos. They frequently have larger maximum apertures than "digital" lenses and can produce stunning results.
What lenses do you suggest getting?
The zoom "kit" lenses that come with these cameras are surprisingly good, despite their low cost. They also cover an adequate range--the 35mm camera equivalent of about 28-80mm. They are fairly lightweight, but they're no speed demons--f/3.5 is their largest aperture at the wide-angle setting shifting to f/4.5 and even f/5.6 at the telephoto end. However, they'll give you tack-sharp pictures up to 11x14 and even larger. Depending on your needs, you can then pick up a longer or wider lens. If you're going longer, there are many used 35mm film camera lenses on the market that are real bargains.
What about memory cards?
Nikon and Pentax dSLRs use either CF (compact flash) or SD (secure media) cards depending on models. Canon and Minolta use CF. Olympus uses either CF on some cameras or a two-slot combination of CF and xD in their latest D-500. You don't have any choices here except to live with what your camera takes, except that you can use an adapter to convert xD cards to CF. On a more practical level, you'll want to buy cards that are fast and can accept images from the camera quickly so that you can shoot without waiting. Sandisk Ultra II cards are a good choice--they're inexpensive and do a fine job. For card speed comparisons go here: http://tinyurl.com/lqhq. Don't be tempted to buy a card with a humongous capacity--1GB is plenty. Heed the old saying about putting all your eggs in one basket.
Why so many buttons and dials?
Despite the apparent complexity, those buttons and dials make it easy to use dSLRs. As you deep dive through the menus of the current camera you own, I'll bet you've said at least once: "Why don't they have a button that does this!" Most dSLRs limit menu items to those you usually set infrequently--for example, if you want instant image review or not, or the kind of light metering you want to use and so on. With buttons and dials, the stuff you use all the time is always at your fingertips. And you don't have to use all of them to begin with. My advice is to set the mode dial to Program and then learn the other features one at a time.
Which resolution should I buy?
At the time this was written, Nikon, Pentax, and Minolta cameras in this class had 6MP of resolution; Canon and Olympus had 8MP. There's more to good image quality than megapixels. The way the camera processes the image is one factor. The quality of the lens is another. Individual light-gathering sensors on 6MP cameras can be larger than those on 8MP, theoretically producing less noise. But 8MP cameras are more forgiving if you have to enlarge a small part of the picture because you have more pixels to begin with. If you choose to blow up only half the image on an 8MP camera, you've reduced its resolution to 4MP. On a 6MP camera, it would drop to 3MP. That said, remember that you can get huge prints from a 3MP camera (Kodak used to regularly make 24x36-inch exhibition images from their 3MP, DC-4800 camera that had a tiny CCD sensor--much smaller than that of current dSLRs. So here's the answer: Leave resolution out of the buying equation.
What about dust on the sensor?
Yes, that can happen. And when it does, it'll put little specks on your image, usually dark ones in light areas. Let me reminisce about the bad old days of film. Here was the darkroom drill. You put a negative in a enlarger carrier and then used a blow-brush to go over both sides of it. Then you exposed the paper, processed it, and dried it. And then, dammit, you looked at the finished print and saw 20 or more dust spots. So out came the Spotone #3 bottle and a Winsor & Newton #00 camel hair brush and about an hour later, after using a bunch of tissues to blot the brush and your tongue to cut the fluid, you had "spotted" the print. Hummm, only ten more prints to go. Yes, Virginia, you will get dust on the sensor (or to be more precise, the glass that protects the sensor), but it's hardly a hassle. Just use an Arctic Butterfly from visibledust.com to whisk it off or spend a few minutes in an imaging program to remove it. Only Olympus has a self-cleaning sensor but that, alone, is not a compelling feature unless you change lenses frequently under dusty conditions.
What is "Program Shift"?
With the exception of Pentax, program shift is a feature on most dSLRs. It allows you to shift your combination of shutter speeds and apertures without having to access the shutter or aperture priority modes. Using the control dial (found on all dSLRs) you can spin it to the aperture or shutter speed of your choice and the other will follow along to keep the exposure correct. So if you want to shoot action at 1/1000 second, you just turn the dial until that speed shows in the viewfinder and the correct aperture will also be set. On the other hand, if you want to open the lens wide for a portrait with a soft background, just turn the dial to, say, f/3.5 and the appropriate shutter speed will be automatically chosen.
Are the controls in the same place?
No. Even the same brands place buttons that control identical functions (like picture review) in different locations on different models. And that's not all. LCD monitors for playback viewing range from 1.8 to 2.5 inches and menus are laid out differently with varying degrees of legibility. Nikon and Pentax lenses bayonet on counterclockwise while Canon, Olympus, and Minolta lenses attach clockwise. Even turning the zoom ring from wide to telephoto is different: some to the right, others to the left. So if you've used a Nikon SLR film camera for years and decide to buy a Canon dSLR, be prepared for some re-orientation. -AB
Arthur H. Bleich (firstname.lastname@example.org) is a photographer, writer, and educator who lives in Miami and conducts digital photography workshop cruises. www.dpcorner.com