Originally posted by windhorse Des if you are toying seriously with the same idea then maybe this is for you?
Thanks for the tip @windhorse - I had seen it new for $299 but not $249. Free postage in Aus too. Undoubtedly a bargain.
I'll tell you why I am hesitating, in case any of this is relevant to you or others:
1. Weight - 550g. Doesn't sound a lot (about the same as the DA*16-50) but it's about 100g more than APS-C standard lenses like the Sigma 17-70 C. Even the Tamron 17-50 f2.8 is about 100g lighter. A combination of two, maybe three, compact primes (e.g. FA 28, DA 35, DA 40, FA 43, DA 50 and DA 70) would also weigh less.
2. Range - I have a 12-24, so 24-60 (or 24-70 or 28-75 or 24-90) would be complementary. But on APS-C some overlap would be useful: more width would mean fewer lens changes (especially when we are talking about two fairly bulky lenses). That's why 24-60 and the like are not so popular these days as 16-xx, 17-xx or 18-xx lenses for APS-C.
3. FF advantage? All else being equal, having a FF compatible zoom would be some advantage. But is it really a compelling reason? Even if I do ultimately get a FF camera, it wouldn't be until the price settles down - ie at least two years from now. If I did, shelling out for a high quality wide-normal lens might well be part of the deal. (Might be a decent kit lens sold with it, who knows?) I would be inclined to prepare for FF by concentrating instead on snaring the odd prime (especially at useful FF lengths such as 24 or 28, 135, 200). To put it another way, which do you think would be worth more in 2017: a Sigma 24-60 (or 24-70 or Tamron 28-75) or say a Pentax F 135 (which can now be had for about $300)?
4. Speed - Constant f2.8 would be useful, but not essential for me, especially as much of my shooting is outdoors and I have 35, 43, 50, 77 and 100 primes that are f2.8 or faster. A lens that was a little slower (e.g. the Sigma 17-70 f2.8-4 or even the new Pentax 16-85, once the price comes down) would be OK if the IQ was in the same park. If it isn't, there's always the Tamron 17-50 f2.8, which does seem to be in the same park.
5. Gap - I don't have a wide-normal zoom, except my Tamron superzoom (and actually it's not half bad at the wide-normal end, especially when stopped down). But I'm using primes more often now and as mentioned I have good coverage with primes from 35-100 (maybe too good - hard to justify keeping both 43 and 50). I wouldn't use a DA 15 or 21 much with the 12-24 (which I like very much). If there is a gap, what is missing most is a good wide prime (or prime-standard zoom) between my (near-prime-quality) 12-24 and DA 35. FA 31 and DA 20-40 Ltd are too expensive at present, Sigma 30 doesn't appeal, so that leaves 24 and 28. Still thinking about the FA 28, but as many have said the absence of a current prime between 21 and 31 is an obvious deficiency in the Pentax lineup. There has to be a DFA prime (or premium zoom, assuming the DA 20-40 is not FF compatible?) coming in that range. Maybe the wide zoom shown on the roadmap might be a FF compatible top shelf 12-28 or 15-30 or something like that, which might provide a partial answer? Or maybe 25-34mm isn't really a gap worth worrying about?
6. PP support - The Sigma 24-60 is not supported by my PP program, DxO Optics Pro (Sigma 24-70 and Tamron 28-75 are supported, as are Tamron 17-50 and Pentax 20-40). Makes for more manual processing, and I don't want to switch programs. Might seem a trivial consideration to others, but not to me.
7. Trying to rationalise my kit. I told myself I would have no more lenses by the end of the year than at the start. I'm one behind already!
For all that, I'm still tempted ..! (LBA might be in remission, but there ain't no cure.)