Originally posted by Nicks Ray, this is exactly what I was thinking. As far as I know, the new 2.8 sensors will improve accuracy in low light but it will not fix the real problem K-5 is struggling with and that is the light wavelength issues. I own both K-5 and K30 and it's obvious to me the DO in K30 works really well. I too shoot most of the time in low light with fast lenses and it's been a quite frustrating experience with K-5. One simple thing that I think would've helped K-5's accuracy is for the AF assist lamp to light up sooner than it does. On the other hand I know that when K30 locked focus the accuracy is there. The AF is not fast in low light but at least I know it's accurate. I think it would be a big mistake for Pentax if they don't implement the DO in K-5II as well. Time will tell.
It is good to hear from someone with the K30 and the K5. The AF assist on the body is all but useless, IMO. here is why:
Many lenses block all or part of the light.
It is inconsistent about when it comes on.
It is not very bright.
It has no stripe or pattern to create contrast.
I find that with wide lenses like the DA 15 that have such a large FOV, the dim body light creates so little additional illumination on targets beyond about 5-6 feet that it makes no difference in the focus lock.
The assist light on the 540 is much better, however. It seems more consistent, is centered and clears all lenses, is brighter and has a contrast stripe. Accurate lock in low light is much better with the 540 on the camera.
Back to the K30/K5:
I believe that the lenses are a big part of the problem with AF speed, especially SDM. This would be equal between the two bodies.
While I have not seen significant or consistent AF issues with my K5s, I did shoot a few party pics at work this week with one of my K5s, mostly indoors with flash, but a few outdoors in daylight, and quite a few shots were just not sharp. Oddly, I shot similar shots at my grandson's birthday a week or so ago with the same exact setup, indoor, outdoor, flash, mid-day, and out of 54 shots, maybe 3 or 4 were not in focus.
The only semi-consistent focus issue I have seen until this week, is slight misses when pink'ish young children or baby faces fill most of the screen. They are not all misses, but more than average.
Although all of my earlier Pentax bodies had consistent FF in tungsten light, the subject was usually just in the DOF at f4 or f5.6, so this was not a big problem. Pentax was slow, but otherwise accurate. Of course, those cameras just would not focus at all in light levels well above where the K5 will lock, and tracking anything moving was pretty much impossible.
Anyway, I am starting to lose a bit of confidence in getting the shot with the k5s. I changed to the S type focus screen so that I can better judge the focus point, but there often isn't time to carefully judge the focus point, and the APS sized viewfinders do not help.
Lastly, if the K5II has no DO AF module, I would be more tempted to pick up a K30 than a new K5II.-3EV is truly shooting in the dark, but -1EV is fine with me if it nails the focus consistently.
Ray