Compared to the Pentax Optio S and Casio EX-Z3

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

• Canon PowerShot SD100: Manual record 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
   
• Casio EXILIM EX-Z3: Normal exposure 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.

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

Between the three cameras the Canon comes second to the Casio EX-Z3 for visible sharpness, although it's a close run thing. If you look at the finer detail such as the gold text on the black background and the barcode the SD100 looks a little better with these fine details (the EX-Z3 goes a little blotchy on the gold text), the SD100 image also has less visible noise than the Casio.