Distortion & Colour

Sony/Ericsson K800i Mobile Camera Phone (Full Frame)

The inbuilt 5.2mm f2.8 lens roughly corresponds to a 35mm wide angle in 35mm, or 24mm or an EF-S mount. Note the well controlled distortion: just a touch of waveform in the corners. It’s not subtle, but it’s a bright and bouncy image. If only the 18-55mm kit lens were as well behaved:


Canon 350D / Canon EF-S 18-55mm at 24mm / f8 (Full Frame)

Barrel distortion clearly evident even in this relatively unrevealing shot, and quite a difference of opinion about colour between the 350D / Rebel’s Fine Quality JPEG and the Sony Ericsson K800i. Let’s go to the benchmark 5D:

Canon 5D / Tamron 28-75mm at 35mm / f8

The Tamron is pretty well corrected at 35mm, with only a hint of waveform distortion visible. The 5D image was captured in RAW and processed through C1 to benefit from benchmark shadow detail extraction and colour accuracy. As you can see, for colour, the phone is closer to the truth than the 350D with the kit lens. Impressive.

Let’s look closer at the histograms . . . .

Sony/Ericsson K800i

Note the combing artefacts indicative of actual size PS colour correction. Well controlled highlight clipping here is encouraging, but there are signs that shadow detail extraction is a problem.


Canon 350D / Canon EF-S 18-55mm

Canon 5D / Tamron 28-75mm

Nice, smooth – though markedly different – histograms. You only get this with untouched captures, RAW processing, or when downsampling from an information-rich source, such as when converting from 16-8 bit or, in this case, bicubic resampling colour corrected images down to 2,048 pixels.