Originally posted by UncleVanya The 28-105 is lighter and has a bit more on the long end and less on the short end. I know a lot of K1 users who own both and use the 28-105 a lot more than the 24-70. It is purportedly very sharp. The need for f2.8 is what distinguishes the two lenses - and the need for wider views.
As for L I’m not aware of any D FA L lenses. The DA 35 (f2.4) and DA 50 (f1.8) aren’t technically DA L lenses but share many of the same characteristics. The DA L lenses are typically the same optically but with a composite mount and without quick shift focusing. There is nothing wrong with these lenses but generally they are crop only as are the DA versions. Some may cover larger than just crop sensor you’ll have to read about them to know.
If you think the weight of the 24-70 and the lack of 71-105 wouldn’t bother you, and/or you can’t live without 24-27mm or f2.8 then get the 24-70. On my Sony FF I have their 24-105 f4 and I have no plan to add a 24-70 f2.8. I have an 85 f1.8 if I need shallow depth of field portraits and the high ISO performance makes the extra cost and weight of a 24-70 f2.8 a non-issue. Honestly I also bought a 28-70 f3.5-5.6 when I thought the 24-105 was only a temporary loan and recently gave that to my father. I liked it for the size and weight and genuinely miss it despite it having warts compared to the 24-105. I think the cost of adding the Pentax 28-105 is low enough particularly when buying it in a package that it is hard to justify NOT getting it.
I'm just going over the review of the 24-70 f2.8 right now.
HD Pentax-D FA 24-70mm F2.8 ED SDM WR Reviews - D FA Zoom Lenses - Pentax Lens Reviews & Lens Database
For me, it's a difficult decision. Yep I like to capture wide scenes though there is only 4mm between the 24-70 and the 28-105.
I think the biggest concern I have with the 28-105 is the low-light capability.
At night I become a little bit like a moth attracted to a flame whenever I see bright lights.
Because of this aspect and the fact that I don't take many pictures during the day unless on vacation somewhere scenic I need something that will have good night performance.
Based on everybody's suggestions it might be worth going for the 24-70 initially, then later on going for the 15-30 and further down the line the 70-210.
Those 3 lenses should pretty much cover all my bases....
Though one thing that I am trying to understand is with those 3, is there any need for a fast prime?? Weight savings to one side.... is f2.8 good enough for low-light level / full darkness work or is it better to go down to f1.8 or even more open ie. F1 or f1.4??
If I can figure this out, then I should be good to go with a longer term plan. I would rather get something that I would use often then leaving it off the camera as simply a "just to have" lens.