Compared to...

Studio scene comparison (JPEG)

This is our standard studio scene comparison shot taken from exactly the same tripod position. Lighting: daylight simulation, >98% CRI. Crops are 100%. Ambient temperature was approximately 22°C (~72°F).

Pentax K-x vs. Nikon D5000

Camera settings:

• Pentax K-x: Pentax 50 mm F1.4 lens, Aperture Priority, ISO 200
  JPEG Large/Fine, Manual WB, Default Parameters (Bright CI), Self-Timer
   
  
• Nikon D5000: Nikkor 50 mm F1.4G lens, Aperture Priority, ISO 200
  JPEG Large/Fine, Manual WB, Default Parameters, Self-Timer
  

Pentax K-x	Nikon D5000
5.1 MB JPEG (4288 x 2848)	5.2 MB JPEG (4288 x 2848)

Unsurprisingly there is only very little difference between the image output of the Pentax K-x and Nikon D5000 - both cameras are built around the same 12.4 MP Sony sensor. Colors and tones are near identical and only at very close inspection is it visible that the Pentax uses a marginal amount more sharpening at default settings. Even at very large print sizes would the output of these cameras be pretty much indistinguishable.