Imagine that your digital camera's image sensor is a parking lot. All of its little pixels are parking spaces.

Now imagine that the individual points imaged by the camera's lens are cars, trying to fit into the parking spaces.

If the parking spaces are big enough, everything works out fine. In a digital camera, this produces a sharp image.

If we want more cars in the same parking lot, we can make the spaces smaller, to squeeze in more cars. This will work, but only up to a certain point.

If the spaces get too small, the cars can no longer park in a single space, and start to crowd out the spaces around them. In a parking lot, this would lead to chaos, and a lot of smashed-up cars.

This is a pretty good analogy about what happens when you try to jam more pixels into the same size image sensor on a digital camera. In most cases, the numbers look great in the advertisements but the result, in terms of image quality, will be a mess. This is one of the reasons why DSLRs, with their large image sensors, produce higher-quality images, while superzoom cameras like the FZ35 with their tiny, crowded sensors have such a struggle producing high-quality images.

Smaller pixels are also noisier pixels. This has to do with the laws of physics. The crowding of more pixels onto an existing image sensor increases the noise. To some extent, this can be handled by improving the processing in the camera's onboard computer. But even with this, there's a limit.

Let's look at the history of the Panasonic cameras leading up to the FZ35 (Pixel density numbers courtesy of dpreview's online camera database):

FZ18 -   8 megapixels - 32 MP/cm² pixel density
FZ28 - 10 megapixels - 36 MP/cm² pixel density
FZ35 - 12 megapixels - 43 MP/cm² pixel density

For comparison, Panasonic's DMC-GH1 has a 5 MP/cm² pixel density.

The FZ18, with its less-crowded image sensor, produces the highest quality images of the three cameras, but it handles the higher ISO settings poorly, with lots of noise.

The FZ28 had better image quality at the higher ISO settings, thanks to its improved processor.

The FZ35's image quality is close to the FZ28's but, with its increased pixel count, it's a struggle that doesn't always work out that well. The FZ35 has 50% more pixels than the FZ18.

So how is the FZ35's image quality? About what you would expect from jamming yet more pixels into the same size sensor. A little less sharpness, but that's hard to quantify since, with its increased pixel count, you'll have to look at less of the image to compare it with earlier models.

And now there's some color fringing (red and green), which was pretty much absent on the earlier models. (Some people refer to this as "chromatic aberration.") But, thank goodness, it's mostly in areas of extreme contrast so it only showed up in a few shots.

And there's color bleeding as well, especially at the higher ISO settings (800 and 1600). Again, this won't be noticed in most shooting situations.

If you're shooting raw, you probably won't see any appreciable difference until you get to ISO 800 and above. Here, the raw processing seems to control the color bleeding a little better than the JPEG format. But in terms of overall quality, it's still pretty close to a correctly-shot JPEG, except at high magnification. So it's going to be a question of whether a tiny gain in image quality is worth the effort involved. There is no real answer to this issue. It's a matter of individual taste.

All in all, the FZ35 manages to keep up with the FZ28 in terms of image quality. The pictures lack the crisp detail of the FZ18, but for most purposes, the sharpness is more than adequate. And there is a little more noise than on the earlier models. Again, you reap what you sow -- more megapixels only helps the marketing department.

But get this straight, the FZ35 is definitely the best in its class. In terms of its new features and its performance across a wide range of ISO settings, it's probably the best go-anywhere, shoot-anything camera in this Panasonic series.

Another reality -- Here's the real-world impact of adding 50% more pixels:

Increased storage requirements in the camera's memory card
Increased storage requirements in the computer's storage on disk
Increased memory usage In photo editing programs
Increased processing time in the camera
Increased processing time in photo editing programs on the computer
Panorama programs will take longer
Making thumbnails and cataloging will take longer
Raw "development" will take longer
Transferring pictures from the camera to the computer will take longer
Loss of the "Unlimited" burst mode in the FZ35

Here's the bottom line. When you do something like adding more megapixels, it should make the camera's images noticeably better. Adding 50% more pixels should produce a stunning improvement in image quality. Otherwise, why bother?

The engineers at Panasonic are wizards, but the marketing people make too many of the important decisions.

Note: The FZ28 and FZ35 have a slightly larger image sensor than the FZ18. This is why the 50% increase in pixels between the FZ18 and the FZ35 only brought a 35% increase in pixel density.