Originally posted by mrt10x Now there is a smiley.. but I was pretty serious. I have been shooting Pentax for 35 years, so dont go all postal on me.. but if I was shooting in low light all the time I would do whatever it took to get into a Nikon D700, Its high ISO performance is light years better than Pentax's. I love my K20 and my K10, but high ISO is their glaring weakness.
An odd perspective coming from someone who has been shooting for 35 years, then - even the K10D is already at least a couple of stops better than 35mm film in the high ISO department, and the K20D somewhat better than that. The D700 isn't "light years" beyond that - it's another stop or so. That extra stop or so you get by going from an APS-C to a FF digital camera kind of pales in comparison to the improvement one already gets just by switching from 35mm film to digital. And Pentax cameras do as well or better than any other APS-C cameras.
So Pentax DSLR's are certainly not weak compared to 35mm film or to other APS-C cameras. And if they do maybe a stop or so worse than a camera system costing thousands more, that's hardly a "glaring weakness", either.
All that said, yes, of course, going to a FF sensor with larger pixels will provide improvement. Whether it is worth it or not to any given photographer or not is another matter. It is possible to get fine results from Pentax DSLR's at ISO 3200 - fine if you aren't trying to print posters, anyhow.
Here is a sample ISO 1600 image from the K200D. The K20D would presumably do even better. This was also done with manual focus, BTW:
Could the D700 have improved on that somewhat? Sure. Would it be worth the thousands of dollars it would have taken to upgrade the camera and get the correspondingly longer stabilized lens? I guess that's for each person to decide for themselves. I'm happy enough with images like the above that no way would I be feeling the need to spend thousands more to get whatever marginal improvement a D700 would provide.