ideally you'd have both (given enough time), but it really comes down to what you shoot more. both lenses will eventually be in my kit (currently 10-135 + primes)
personally, i'd get the da* 300 before the 60-250 'cause the 50-135 covers a pretty good range. the extra 100mm in a zoom is sweet, but i dunno if it's worth the cost of a stop; where as a prime at twice the fl is definitely worth it. if you're a birder, the zoom makes more sense.
on a crop sensor you're really comparing 16mm vs 24mm, so there is a difference. does it matter to you? depends on what you do. if landscape or cityscape is what you like, the 12-24 is more suited to the task than the 16-50 (reason i'll be getting it); for people it's really not that different (a fisheye becomes more useful at 17mm [24mm]).
A lot of opinions here. To me, I got my first chance to handle the 60-250 and it is one big honkin' lens. I have a Tamron 18-250 which reminds me of the 60-250 from a range perspective. Since I'd view the 60-250 as more telephoto than anything else, I think if I owned it I'd want more range and would as someone suggested go with the DA*300. I own the DA 55-300 (my third lens in this range) and it fills the need that the 60-250 would mostly replace. It's smaller and cheaper and get it done from an IQ and tele point of view. Might be something to consider.
I've only spent a little shop time with the 12-24 and it's on my list for the future as it's the lens for buildings - or that's what all the reviews say. I love and own both the DA 10-17 and the DA*16-50 and they are both great lenes (I know what you mean about the 16mm end of it), but I would still want the 12-24 for building shots, you can't get them right with either the DA 10-17 or the DA*16-50.
Since you are trying to figure out what one lens to go with, it seems to me that you you should go with a telephoto to extend your reach and make do on the wide end for now with your 16-50.
I would go for the 12-24, as it gives you the wide area you want and seem to miss from the 16-50.
With those 3 you have the basis of a good kit for everything for birding.
I would not get another zoom for birding but perhaps someting in a 300mm F4 lens, and combine it with a 1.4x to 1.7x TC to get extra reach. birding really needs 400-500mm hence the TC
getting the 60-250 has too much overlap to the 50-135 and not enough speed to make it worth while as a second lens in that range.
i wanted to sell my 12-24 to buy the 16-50, but because of QC issues on the SDM and the 16-50 in particular, i'm holding off.
moreover, the distortion of the 16-50 at the wide end is not great, plus 12 vs 16 is quite a difference.
i'd get the 12-24 and the 55-300 instead. that would give you about $300 extra had you gone for the 60-250
Both of your suggestions are top quality choices.
I would personally not got for the 55-300 unless you're going to be shooting in full sunlight in most situations for wildlife - even then, it will not come close to the quality of images your 50-135 will produce for you. The 60-250 is well known for its superior IQ, though is costly. Another option is to go for one of the 70-200 lenses with a 1.4x TC.
Now the 12-24 is in another league of wide-angle lenses - if you find yourself wishing to go wider than 16mm, you probably will find MANY applications for the 12-24, and shooting a lot of shots at 12mm. It really is a great lens. But both the 12-24 and 60-250 are just so different, you'd have to find out which one you'd want to have first (as you may well just have to get the other one anyway at a later stage)...
Two totally different ends of the spectrum. I own the 12-24 and love it, using it often.
I handled the 60-250 at the K-7 tour in Redondo Beach and really struggled with its size (I'm a small female, someone larger might not have as much trouble). I didn't feel like I could use it effectively hand-held under most conditions, though the couple of sample photos I took with a K-7 indoors didn't show signs of camera shake. I came to the conclusion that in theory the lens is an excellent idea, the optics are outstanding but it was just not practical for me, personally. And I couldn't come up with a good reason for buying it, if you want to shoot wildlife one of the 300mm lenses make much more sense. I'm not trying to run down the 60-250 lens at all, by the way. It seemed optically outstanding, a lens that would provide excellent pictures. But it wasn't a lens I found comfortable to use or one that reached out and grabbed me and said "buy me, buy me, you won't be happy until you do."
An idea might be to get the 12-24 and then look around for an A*300 or save up for the DA*300.
Though even a 2x TC would not even give 300mm of FL, and degrade IQ significantly at that..
Why ruin a perfectly good lens?
But seriously, just depends on HOW much extra reach you need Alfred.
Just a little more? A 1.4x TC may just do it for you (an added 54mm) and not affect IQ significantly, though AF may not perform as well as without the TC.
More than this? You're looking at another lens...
Go for the 12-24mm and try a 1.4 or 1.5x tc with the 50-135. If you find the 50-135 lacking for your wildlife/long shooting (and you are doing a lot of it), invest in a 300mm prime when you have the $s. The tc will give you some additional reach with the 300mm and minimal image degradation. If you decide on a tc, make sure you get one that will autofocus with the 50-135.
I want to thank everyone for their advice and opinions =)
I'm going to go for the 12-24. I'm going to pass on a K7, and wait for the body and focus on lenses. Being able to hand hold a lens is important to me, I'm still leaning towards a 60-250 vs a 300mm. But, things could change if the Pentax SDM teleconverter is good, if it is, maybe I'll get a 200mm 2.8 and a Pentax SDM TC.
Thanks again everyone, this is such a great forum =)
personally, i'd get the da* 300 before the 60-250 'cause the 50-135 covers a pretty good range. the extra 100mm in a zoom is sweet, but i dunno if it's worth the cost of a stop; where as a prime at twice the fl is definitely worth it. if you're a birder, the zoom makes more sense.
I concur! I have the 50-135 and 300 that I had traded for a Sigma EX 100-300. Found that I was using the Sigma at the long end only so thought might as well just have a 300.