Compared to the Casio EXILIM EX-Z3 and Canon SD100

These three ultra-compact digital cameras all have three megapixel CCD sensors. From a size point of view the Pentax Optio S is the smallest (and lightest) followed by the Casio EXILIM EX-Z3 and then the Canon PowerShot SD100.

Studio scene comparison

• Casio EXILIM EX-Z3: Normal exposure mode, ISO 50, Default Parameters,
  Manual preset white balance
   
• Pentax Optio S: Program AE (P) exposure mode, ISO 50, Default Parameters,
  Manual preset white balance
   
• Canon PowerShot SD100: Manual record mode, ISO 50, Default Parameters,
  Manual preset white balance

Each square crop is a 200% magnification of a 80 x 80 portion of the image.

Pentax Optio S	Casio EXILIM EX-Z3	Canon PowerShot SD100
ISO 50, 1/8 sec, F3.1	ISO 50, 1/8 sec, F3.1	ISO 50, 1/10 sec, F3.5
1,857 KB JPEG	1,622 KB JPEG	1,312 KB JPEG

Overall the Optio S delivered a softer image, which was surprising because it has the same lens system as the EX-Z3. Looking closer we can also see that Pentax's default sharpening is considerably less aggressive than the EX-Z3. Color balance was on the whole good, I would have preferred slightly more saturated greens (this is something Canon appear to have nailed).