Originally posted by audiobomber The firmware upgrade is definitely worthwhile, but the K-01 is never going to equal PDAF for low light autofocus, not even compared to an older DSLR. Compared to a current DSLR, low light AFwith the K-01 is just plain bad. In good light, CDAF works well, but for long tele an OVF is far superior to an LCD viewfinder. Focus Peaking is a fantastic feature, but with a 200+ mm lens, you'll probably still want to use focus magnification and a tripod.
I like my K-01 a lot for its strengths, but it is not a a DSLR. If you want one for what it does well, you're all set. If you're satisfied with your DSLR, the K-01 can be a great addition. If you're looking to upgrade your DSLR, the K-30 beats an *ist in every imaginable way, and has the same CDAF and focus peaking as the K-01. I'm sure the seller wouldn't mind you requesting an upgrade and honestly, that's what I'd recommend. The K-01 is a super deal, but if it doesn't offer exactly what you want, then it's not such a great deal.
BTW, don't worry about upgrading the firmware. If you return the body, it will be re-sold as open box. The dealer won't care what firmware it has as long as it works and the buyer will benefit from the v1.03 upgrade.
The main problem was not auto focus speed but rather it would fail to auto focus at all. There are two adjoined rooms so I was shooting from maybe 25 feet (it had no problems in the 10ish or less ft range with the same lighting due to af assist I assume). At first I was using lenses at the long end so f5.6 (lenses like a 28-90mm). When I realized it might be the slow lens, I tired my 28-200mm in the middle range so I could get a stop faster, and tried other lenses middle range a stop faster. Even with the kit 40m 2.8 it seemed to struggle a little at that distance and lighting. I also tried a 28-80m thats 3.5-4.7 in the mid range (I think it went to f4) and that didn't help. There are 2 26 watt flouresent bulbs (100 watt equivalent) in that room, and a chandelier with 5 40 watt equivalent bulbs in the room I was shooting from, so it wasn't that dark. I tried with the ist-ds ad same lenses/settings and it struggled a little bit. I have never had significant complaints about the ist-ds's ability af in low light.
The primary reason I wanted a new camera was low light performance as that is my only significant complaint about the ist-ds. From a high iso perspective, the camera achieved that low light performance very well. I guess I need to update the firmware and try more shooting scenarios to see if it will be usable. If it can detect focus when manual focusing in such situations (where I'm controlling it and keeping it right there till I get conformation). I do have faster manual glass if that is what the problems is. As this might serve as a good video camera too, it might still be worth it if it can handle a lot of lower light situations (even if its in manual mode or with manual faster glass). Not dark situations, just normal room lighting. With the ist-ds, low shutter speeds/terrible look of high iso was the problem, not the ability to auto focus. Its worth trying the firmware upgrade but I might have to wait till tonight to try it out (there is a lot of bright sunlight coming through the windows right now).
The AF sped in general seems acceptable. It seemed similar to the ist-ds but opposite kind of. In other words the ist-ds strong points were the k-01 weak points and vica versa. When the lens hunts (as in goes through the whole range looking for focus) the k-01 was slower. When it was just making adjustments the k-01 seemed faster, despite the nature of how it focuses (has to focus past and then back but was very zippy about it). In bright light, even with my f 100-300mm (almost a full rotation of AF throw), it was tolerable on the k-01 though certainly not fast.
I guess its a mute point till I update the firmware and see how it performs.