Originally posted by narual You must have much, much, much steadier hands than I do. Even at 135mm, 1/25 would probably be soft for me, let alone the 200mm the OP used.
I fully expect my hands to become less steady in the coming years, but for now it seems to work. The OP's daughter is about the same age as mine, so there's a reasonable chance he can use a similar shutter speed - especially if he properly braces the camera using his left elbow against his chest and his left hand supporting the camera/lens.
Originally posted by clackers And neither does the Pentax in-body SR work as well as in-lens on a tele, AFAIK.
The subjects being distant, moving and separated called for wider aperture than 7.1 and higher shutter speed than 1/100.
Reports are that the in-body SR works similarly (or possibly better in some cases) than the in-lens OS on the Sigma 70-200/2.8, which gives you a choice. But this is irrelevant for most Pentax-mount lenses, which lack any type of in-lens OS anyway.
I never bought the DA50-200 (I went straight to the DA55-300), because I could see from sample photos that it was only mediocre in IQ. So I can't be too specific here, having not owned it. But my experience with similar lenses tells me wide open at f/5.6 at 200mm will significantly compromise IQ on this lens. This is one of the reasons people will spend so much on a DA*200 (which I owned for a while) - because you can get excellent IQ near wide-open at ~f/3.2, as opposed to getting lesser quality even around f/8 on this lens. Even the better DA55-300 shouldn't be shot wider than around f/6.3 at 200mm, IIRC (but it gives pretty good IQ - especially between 55 and 135mm). So wider than ~f/7.1 will compromise IQ too much on this lens, even though I'd shoot this shot closer to f/4 when I could (as on my K200/2.5).
But considering all the factors for this shot, I'd use Av mode at around f/7.1, manually select my focus point, set ISO to 800 (which still has low noise), and allow the shutter speed to go to about 1/500s (which it would). Then I could even turn off SR if I wanted. But since they're posing and not moving, I wouldn't hesitate to use SR and a much lower shutter speed around dark.