I made the stunning revelation in my last column that I'm partial to single-lens-reflex (SLR) cameras--not really surprising, since a lot of avid photographers are. Choosing a camera type has become complicated for enthusiasts recently, though, with 6-megapixel SLRs and 8-megapixel electronic viewfinder (EVF) cameras falling into the same price range. (If you're choosing between point-and-shoot cameras with optical viewfinders and EVFs, take a look at my last column.)

What makes an SLR an SLR anyway?
Before I get into the reasons why I favor SLRs, here's a little background information for those of you who aren't camera geeks: Many people think of SLRs as cameras with interchangeable lens systems, which most of them have, but an SLR is actually defined by its viewing system. Basically, it works like this: Light comes into the lens and hits a mirror, which in turn directs the rays to a focusing screen where the image is resolved. Then a prism between the focusing screen and the viewfinder eyepiece reverses the incoming image so that you can see it the right way around. When you take a picture, the mirror flips up so that the light goes straight through the lens to the sensor (or the film plane in a film camera).

So why do I like SLRs? When I look into the viewfinder, I can see every little change in focus. And no matter how close to my subject I get, I don't have to worry about my framing being off because of the parallax error that results from using a viewfinder that doesn't look through the lens. With most SLRs, I can get a depth-of-field view, too, so that I can see how much of the area around my point of critical focus is sharp. (To see what I mean, take a look at Photozone's online Depth-of-Field (DOF) Preview example.) I also expect fast performance, a broad feature set, interchangeable lenses, and compatibility with accessories and studio gear--not because any of that is necessary with an SLR viewing system, but because the advanced photographers who buy SLRs demand it.

Why SLRs are better than EVFs
Photographers choosing between an SLR and an EVF camera have a personal decision to make. If critical focusing is important to you--say, for macro or portrait photography--I advise going with the SLR. I have yet to see an EVF that can match an SLR viewfinder in showing the fine detail you need for really careful focusing.

Likewise, if you do much shooting at night, I can hear you cursing your EVF already. When it gets dark out, EVFs get dark too. Some cameras counter this problem by boosting the gain so that the image is bright enough for basic composition. But as soon as you increase the gain, you get a noisy, fuzzy picture, and manual focusing goes out the window. That can be a big problem if the low light level also makes your autofocus fail, which is especially likely if you're photographing a distant subject that the autofocus assist lamp can't reach.

Action photography is another area in which SLRs trump EVF models. When you release the shutter on an SLR and the mirror snaps up, there's a momentary viewfinder blackout. But that's nothing compared to the extended blackouts some EVFs have when you're taking a fast series of shots in continuous-shooting mode. Other EVFs try to give you at least a fleeting look at your scene between shots, but in my experience, they just can't hold a candle to the view you get with an SLR.

Why EVFs are better than SLRs
Before you start placing your order for an SLR, ask yourself how often you focus manually, shoot fast action, photograph in the dark, or feel the need to switch lenses. Not much? Then consider this: SLRs are heavier, bulkier, and louder (thanks to the flipping mirror) than EVF cameras. The advanced EVF cameras on the market now have feature sets that rival those of consumer SLRs. They also have LCDs that you can use as viewfinders for greater shooting flexibility. You won't find one of those handy fold-out-and-swivel screens on an SLR.

And EVFs give you a through-the-lens view of your whole image frame that shows both exposure and focus changes, even if not always as precisely as you might like. One of my biggest pet peeves about consumer digital SLRs is that they don't give you a 100 percent view of your image, which makes it easy to accidentally capture the elbow of a bystander on the edge of your otherwise perfect shot. Yes, I know you can crop it off later, but I prefer a camera that saves me the trouble. Kudos to Olympus for making the only current sub-$2,000 digital SLR with a 100 percent view, the E-1. Sigma's SD10 runs a close second with its approximately 98 percent view, but the other options show you about 95 percent of your frame.

Video capture is another thing you'll miss out on with an SLR. The way that reflex cameras are constructed just doesn't lend itself to capturing moving pictures. Models with EVFs don't have that problem, and in fact, shooting video with them is as close to a camcorder experience as you'll get with a still-image camera. Now that extended recording times, 640x480 resolution, and rates of 30 frames per second are becoming more common features, shooting video that's worth watching on a TV has become a real possibility with a still camera. Don't get me wrong--the video quality you'll get from an EVF camera won't compare to footage from a digital camcorder. But if you're a serious photographer and a casual videographer, an EVF camera with advanced video features might offer you just the right combination.

So now that I've told you what I think about the SLR vs. EVF issue, I'm curious about your opinion. Do you love EVFs and think that my SLR favoritism is stuffy and inflexible? Do you love SLRs and wish that EVFs had never been invented? Let me know.