Only interest is bird/wildlife photgraphy. Decided to buy Sigma 150-500 zoom telephoto lens but appreciate advice on camera to suit.

Reviews say that this Sigma lens gives best images at f8 or f11. My understanding is that to get the fast shutter speeds needed at either of these apertures will require med to high ISOs.

Camera reviews in the current 'What Camera? 100 Cameras Tested Winter 2012' on the Pentax K5 and K30 indicate that both of these Pentax models produce images that are generally acceptable up to ISO 3200.

Has anyone with any experience of using either of the cameras with the Sigma 150-500 lens able to comment please?

Best wishes for 2013 to you all.