Originally posted by CrazyNuts Thanks everyone for your opinions and advice.
I think I will do as has been sugested and try out the K-5. I'm a bit cautious about the K-5 due to so many issues with it from the day it was released.
Someone asked me what my issue with AF is (and my skill was being questioned). AF I find is just TOO SLOW. Not the lenses, I have had quite a few lenses which are VERY quick to focus (i.e. Sigma 100-300mm f/4) and even though the motor on that lens is lightning quick, the camera would hunt then micro adjust before locking focus. This was the same on my K10D, K-7 and also my current K20D.
Maybe it's just the conditions I shoot in that are beyond the capability of the AF, regardless of brand. I will be doing some further testing before making my final decision.
I don't have any issues with the AF in bright daylight, of course. The K20D and K-7 performed fine, it's just the low light conditions I regurarly shoot. Think of "night clubs" and that's basically the conditions I have to deal with and the type of people too. I do a LOT of events (all for free).
It is evident there are a few fanyboys here and will attack the photographer (without even knowing me) than admit there are a few flaws with the system. I'm not one to be blaming my tools before my skill, but I have definitely become fvery familiar with the camera's limitations and asjust my shooting style to suit. Sometimes, thought, that isnt enough and I miss out on the golden shots.
Before anyone asks, yes I have tried shoot in MF (hence why I have a small MF lens collection) but I found that too slow, especially in dark scenes as it's hard to find that focus point.
I shoot quite a bit in max aperture
If it is for live music etc in low lit clubs all brands suffer on the speed (I've shot music for years and have friends using all brands) the faster lenses make a difference. a Tamron 70 -200 2.8 just isn't that fast in the scheme of things and screw drive lenses do hunt more than SDM/USM lenses (my sigma 24-70 2.8 suffers the same as it's an older model screw drive not the newer usm type.)
I haven't tried a K5 (i use a K7) but I understand it is faster than my K7 (and my K7 seems fast and accurate compared to my K10)
The biggest issue i see if you want to move over is what it costs to get the best performance out of the system. The Body isn't the issue it's the high end glass which costs an order of magnitude more
Try a 50-135 with a K5 and compare that to the others. also you might look for a faster prime than the DA70 (look at the sigma 85 1.4 or 50 1.4 bot very fast focusing AFAIK)
All that being said I think you can shoot what you shoot with manual focus lenses (hell it was the only way when i shot the early punk scene in London and Toronto back in 76-77, and light in those clubs was as bad as you'll ever see and it was a frenetic scene as well so needed speed. Like shooting sports the trick to MF in this scenario is to predict action rather than the spray and pray of modern fast af systems with unlimited shots at no cost.
Reality is crappy tungsten (or even worse LED) club lighting is a challenge to all AF systems