It used to be that a serious photographer could be spotted by his Single Lens Reflex (SLR) camera. An adaptable marvel, the camera -- with the change of a lens -- could be modified for any photographic task, from taking near microscopic close-ups of flowers to capturing telescopic shots of the moon.

The one thing it did not easily adapt to was the digital age. Early attempts to wed SLR flexibility with digital technology resulted in cameras that fell short as either SLRs or digital cameras.

The hobbyist photographer had two basic choices: mothball a camera bag full of lenses and attachments and switch to digital, or pony up $5,000 or more for a digital SLR that was compatible -- maybe -- with the old gear. Not anymore. Camera manufacturers now make full six megapixel digital SLRs for less than $1,000 that stack up nicely to both their digital and film brethren.

Two particularly notable models are on the market now -- the nearly year-old Canon EOS Digital Rebel (also called the EOS 300D and Kiss Digital) and the newer Nikon D70. Both offer the flexibility and quality of your old SLR and the immediate gratification of digital photography. Either will have a very familiar feel to an SLR user.

You may be wondering: Why shell out a grand for a six megapixel camera when you can get an eight megapixel compact digital camera for the same money? Megapixels are the little dots that make up the image the camera records, and generally, the more pixels the better. But in this case, megapixels alone don't tell the whole story.

In the new six megapixel SLRs, "the sensor is physically much larger and each pixel is larger," said Richard LoPinto, Nikon's senior vice president for product, technology and engineering.

That makes a quality difference. The larger each pixel, the more light it captures, meaning there is more accurate information from each pixel. The final picture has better color and light data for a clearer image. It will also have less digital "noise," which looks very similar to grain in regular photographs. Noise shows up in even-toned areas like sky. The lower the light, the worse the noise gets, and it gets worse still the larger the print.

The pixels are bigger in the SLRs because the whole CCD -- the sensor that turns light into information -- is larger. The CCD in the Canon Rebel SLR is 15-by-22 millimeters -- the size of a commemorative postage stamp, says Chuck Westfall, Canon's director of technology information. On a Canon compact, the sensor can be as small as 4-by-5mms, with an additional 2 million more pixels crammed in.

Digital SLRs are also reasonably free of "shutter lag," that annoying quality that makes it seem as though your camera takes the picture about a half-hour after you push the shutter button.

Part of the reason is that from the time you press the button, an SLR has fewer functions to perform than a compact digital. Just one example: When you compose a picture using the LCD screen on a compact, the camera lens is open to the best lens setting for the LCD. But that may not be the best lens setting for a picture. So when you press the button, the camera has to switch off the LCD, readjust the lens opening and focus. Although each operation takes place in the wink of an eye, the winks add up. The SLR skips some of those steps because you don't compose using LCD (although it shows you the results on one afterward).

On the downside, SLRs can't match the compact size and light weight of digital compacts. It may not be the top choice to lug around Europe if you just want to come home with some 4-by-6 snapshots.

The SLR mechanism is also a bit louder than a compact's, so if you plan on unobtrusively nabbing a few candids of people on the street or capturing wildlife, you might want a compact (or a very long lens for an SLR).

You're a good candidate for a digital SLR if you already own a regular film SLR, especially if your lenses are autofocus models minted in the past decade. Canon likes to say every lens in the EOS line works with every EOS camera. That means lenses from 1987 forward will work with the Digital Rebel. That's 150 different lenses over time, and about 50 lenses that are on the market right now. Nikon says all of its lenses, regardless of age, work with its new D70. But for all of the functions to work, like autofocus and through-the-lens metering, broadly the lenses need to have the "AF" designation. Those lenses have a built-in computer processor that will let you use most of the advanced features. Both cameras can use third-party lenses and accessories as well.

As to which camera is the better choice, the Canon or the Nikon, that's one photo buffs can debate endlessly. But there are some generalizations that can help you decide. If you already own lenses and accessories from Canon or Nikon, your decision is made -- you'll want to buy the camera that works with all that stuff collected in your gear bag.

If you are starting from scratch, you can begin with price. The Canon has an advantage there; its Rebel with a 55mm f/3.5 lens sells for as little as $950 from reputable e-tailers. The Nikon D70, which the stores I visited are having trouble keeping in stock, isn't discounted often. You'll find it for list price: $999 for the body alone, $1,299 with a Nikkor 18-70mm f/3.5 lens.

The Canon is also a little easier to figure out without the manual, at least for the beginner, although operating either camera in its automatic mode is as simple as using a point-and-shoot.

For picture quality, the guys in the photo shops give a slight edge to the Nikon. But don't forget, that edge comes at a price.

If you still can't decide, give it a year. Like other digital devices, these new cameras just get cheaper and better.

Roy Furchgott last wrote for Travel about Copper River salmon.

Interchangeable lenses pair up with instant gratification as the Nikon D70, left, joins the Canon EOS Digital Rebel, above, in the race for affordable digital Single Lens Reflex cameras.