Interesting Test; Digital cameras

[Man On The Clapham Omnibus]

Never being quite sure exactly what '3x' or '6x' zoom means (6x linear or area?) I thought I'd put it to the test. I have a 2002 model 2.1 megapixel Fuji 2800Z with 6x optical zoom, and a slightly more recent Kodak DX4530 with 5 megapixels and only 3x optical zoom. Taking the practical approach I shot two pictures on each: one at maximum wide angle and one at full optical zoom. Would the 2Mp at 6x be better than or less good compared with 5 Mp at 3x but cropped on screen to represent a 6x zoom. Also which would be better at wide angle.

The results are what you might expect in that the 2Mp Fuji was inferior, but not by a huge amount, at wide angle (uncropped). At full zoom, though, the Kodak's image cropped to equate to the full frame of the Fuji was distinctly 'soft' despite its 2.5 times more pixels when compared with the 2Mp of the Fuji. Because the zoom ratio is a linear figure and the number of pixels is effectively an area figure, the law of squares comes into effect.

Now to do the same test with the digital zoom of the Kodak to make up to 6x, although I cannot see the difference between digital zoom in the camera and cropping on the computer. Unless anyone knows different...

Later: Digital zoom is exactly the same as cropping in the computer. Can't post samples 'cos the compression for hosting degrades the images.

[pistonbroke]

Digital zoom = sales gimmick  

[Man On The Clapham Omnibus]

Yep, quite right but I wondered if, by interpolation, it just might be better than on-screen cropping. It isn't. But a good, high multiplication zoom lens is more important than big pixel numbers for long lens shots.

[nikpro]

You can't generalise like that - all pixels are different.

sensor size also comes into the equation. 3mp from one manufacturer can give totally different results to the same spec from another manufacturer.