[SpecialK]

I didn't want to bring it up earlier, but...most lenses have the best optical performance a couple stops down from fully open. Therefore, a 1.4 may have better performance at 2.8 than a 2.8 at 2.8.

You can't win :-) Just buy what makes you happy. At the worst, you shoud be able to sell it for not too much of a loss and buy something more appropriate after some trial and error and research.

[ugaarguy]

At the worst, you shoud be able to sell it for not too much of a loss and buy something more appropriate after some trial and error and research.

Yep SpecialK, this camera thing is gonna be just like my firearms. You have to jump in and try something. After a little bit you see which charecteristics you want/need, and which ones you don't use. Buy it, get your use out of it, trade it in for something else until you find the keepers. This should be interesting.

[nickmeertens]

It's a 1-stop difference. If you mean how important is 2.0 vs 2.8 in low light, I can't say.

However, if you use a very large aperture such as 1.4, you run the risk of missing the focus, which gets very narrow. If you decide to put it on a tripod so you can precisely focus, then the large aperture advantage is lost :-).

And one stop difference means that double the amount of light enters the lens at f2 compared to f2.8... that is a HUGE difference. In my opinion, zoom lenses are not for indoor use, not even a 2.8. I'd would advice using a prime for indoors and a less bulky f4 zoom for outdoors.

Best, Nick

[ugaarguy]

Right now the Sigma 18-50mm f/2.8 is leading the low light zoom search, with thoughts of a wide & fast prime also being entertained. From post I've read here I see that focal length overlap is good, and that giving up a little on the wide end to gain more on the long end can be good for a utility lens; all of these helping to minimize lens changes.

Pentax SMCP-FA 28-105 f/3.2-4.5 - I can't find much on this lens. At around $200 it looks like a friendlier on the budget than the approx $400 SMCP-FA 24-90 f/3.5-4.5 I've seen recommended here. I think that's what worries me though; what makes the FA 24-90 f/3.5-4.5 cost nearly $200 more than the FA 28-105 f/3.2-4.5? Anyway, I've now got a cross country drive coming up soon, and would like a lens with a bit more range than the 18-55 kit. So, it looks like a good daylight utility lens at a reasonable price would have more immediate utility than the fast zoom. Gotta love how circumstances influence lens desires.