Originally posted by awjweb As Edwood stated, it is disappointing that this issue still exists in the newer models. I have an istDS also and, as I have stated here *many* times, the lowlight autofocus performance is horrendous in terms of speed and accuracy.
Have you tried the K10D? It is miles better than the *ist DS. Edwood was wrong, K10D was a big improvement, including low light AF. Other brand may give an impression of faster AF in low light, because they did not do any final checking. Pentax would move past and back the focus point to ensure accuracy. If you don't need this extra accuracy, just switch to AF-C (no AF assist though), and press the shutter when the lens reach its first stop; that would be the same as what Canon and Nikon do.
Quote: My wife's Oly P&S (c5050z) uses an infrared assist and it focuses very quickly and accurately in low light conditions.
Comparing with P&S is misleading. Because of the huge DOF due to the tiny sensor, P&S's AF is very approximate, and it does not require high accuracy to get sharp pictures. On the other hand, DSLR has to deal with insane narrow DOF in some lenses with errors allowed limited to millimeters.
Actually, P&S's contrast detection is inherently slower than DSLR's phase detection AF. In contrast detection, the camera has no idea which direction the focus should go. The newer P&S does the apparent fast AF in low light by speeding through the entire range of focus, memorizing the highest contrast point, and "snap" back to the memorized point. This is not very accurate, but good enough as it is covered by the huge DOF.
Quote: This is something Pentax can and should address
They already did.