First of all, make sure you like the look the glass produces. For some this isn't a big deal, but for others (like myself) the colors and general appearance of the images is paramount. The Sigma and Pentax will produce different looking images. My preference is for Pentax glass.
Originally posted by MadMathMind I have a Pentax F 70-210 which is significantly lighter that I carry for general shooting, so I only use the Sigma when I know I will use it for most of my shots (e.g., zoo) or when I expect the light to be pretty bad (e.g., concert).
The Pentax F70-210 is actually a very good lens, although naturally it won't give you as much subject isolation as a faster lens. But it's worth considering even if you're not on a tight budget - very good IQ.
If you go with the Pentax get the FA*200, not the DA*. The DA* is very slow in focusing, even though the IQ is nice. I sold mine after less than two weeks because it was useless for shooting runners coming at me.
With Sigma, go with the latest version of the 70-200/2.8 - which often means you need to buy it new (because there seem to be fewer on the used market). Compared to the earlier Sigmas, it has better focusing speed, OS, and I believe a little bit better IQ as well.
If you think focusing speed isn't an issue, you're missing some of the best shots. There should be times when the players are skating towards you and filling the frame - a slow lens or camera won't be able to keep up if you have e.g. the FA*200 at f/3.2 (which is about what you'll usually want to shoot it at). Fortunately the K-3 focuses quickly with these two lenses.
I use only the F*300, FA135, and FA*85 for action shooting, so obviously I'd go for the FA*200 (or F/FA135) here. It's surprising how well a prime works here, even though you don't have zoom. You just take whatever fills the frame, and you frame it properly. You'll end up with some good shots you never would have got if you were able to zoom out like you "knew" you should. As the players move closer or farther you automatically get variety in how they fill the frame, even though your focal length never changes! And it's nice and light for hand holding. But the Sigma's a good lens too - I used one briefly at an indoor dance competition, I just didn't like the results as much.
You could even consider a *300 - it isn't "too long" indoors like some people think. In this case, all 3 focus quickly - DA*, FA*, and F*. It's obviously partly personal taste, but I believe at least some of your action photos should be "intimate," like a few of these are (shot indoors, and like most of my action shots, JPEG with no PP or cropping):
http://www.eventtimephotos.com/Dance/2014/CADTD-State-Championships/Friday/Tops/i-g6sCVbG/A
Just something to think about. If you're serious, you need two bodies (each with a different lens) any way. Good thing the K-3's on sale!
Last edited by DSims; 12-06-2014 at 03:53 PM.