The 8-megapixel cameras achieve sharpness comparable to that of 6-megapixel D-SLRs, but that's not the whole story. Although the compacts record more pixels, the D-SLRs' larger imaging sensors provide cleaner data overall, with fewer image artifacts and markedly less noise. That makes the D-SLRs' images simpler to interpolate and sharpen in the computer when making big prints.
To put this in perspective, a carefully exposed image from a D-SLR using its lowest ISO for best quality displays little or no noise in 16x20 enlargements. In the strikingly grainless clarity of their images, D-SLRs rival 4x5-inch view cameras. By comparison, the 8-megapixel compacts' best 16x20s display a noise pattern reminiscent of 35mm film grain.
Like the D-SLRs, the 8-megapixel compacts achieve their optimum performance at their lowest sensitivity settings of ISO 50 or 100. D-SLRs, on the other hand, have minimum ISOs between 100 and 200. D-SLRs hold the same nominal advantage in ISO speed over the compacts as does 35mm color negative film.
Performance. The 8-megapixel compacts use an electronic viewfinder (EVF) instead of the familiar ground glass of an SLR or a D-SLR. EVFs can do some things that an SLR finder can't, and vice versa. An EVF's chief advantage is that it can provide a live image from the camera's CCD, letting you see exactly what your image will look like before the exposure is made.
The ability to pull data from the CCD beforehand extends to the histogram, which the EVFs of several of the cameras can display. The live histogram can be a real boon in fast-changing light outdoors because its graph of exposure values throughout the tonal range of the images tells you for certain if you've got correct exposure before you release the shutter. On a D-SLR, that confirmation only comes after you review the recorded image, and with film, well...
An EVF's disadvantage is that it can't yet match an SLR's ground glass for clarity, or for the speed with which the displayed image updates. Visually confirming focus or checking depth of field with most of the EVFs here is difficult at best. The electronic viewfinders also black out for much longer than the flicker of an SLR's instant-return mirror. That last characteristic makes it difficult to follow a moving subject for a second or third shot.
Shutter lag with the 8-megapixel compacts also is noticeably longer than the instant response we're used to with SLRs and D-SLRs. That's partly because the compacts' AF systems aren't as quick or sure-footed as those on the larger cameras. Lag shortens considerably with pre-focusing, but the simple fact is that these cameras aren't as fast on the draw as an SLR or a D-SLR.
The Bottom Line I'll never forget the forlorn face of a friend as he stopped to rest on the long trail up to the top of Yosemite Falls. There, about halfway up the 2,400-foot ascent, he unloaded his heavy 35mm system, which included a large 300mm telephoto. Gone were thoughts of making beautiful images; at that moment, he just wanted it all to be over.
The new compact digital camera systems weigh just a fraction of what that heavy gear did in Yosemite. With an extra auxiliary lens or two, the cameras have as much ability to shoot stunning landscapes as my friend's pro system, yet they fit handily into a small satchel, easily carried anywhere.
I've been using the 8-megapixel compacts for some months now, effortlessly making images far up trails where I used to struggle carrying my D-SLR system. By saving even more weight with my carbon-fiber tripod, bringing a full photographic system along on the trail has become a non-issue instead of a challenge for the determined. I won't be trading in my D-SLRs, but I'll be adding a new compact to the arsenal.