My main hobby is garden railways and the price of live steam locomotives makes most photo gear look like a bargain, and you can wait months or years for delivery after placing an order. Good fun though.

Unless it is prohibitively expensive I will get one. I don't need it; I can only think of a handful of occasions when APS-C has been inadequate. But it is a hobby and a part of the enjoyment of most hobbies is playing with new toys, so why not?

It is a very handy lens for parties and other social events where you are working at close quarters. If you want something reasonably wide that is faster than f2.8 there are not many options. I used to use the Sigma 24mm f1.8 but the 18-35 is much more versatile, so the 24mm will sit in the drawer until FF comes along.

I have not used my Sigma 17-70 since I got the Pentax 16-85. Not because I am unhappy with the Sigma, it is a great lens. But the Pentax has equally good picture quality, plus weather resistance, greater range and near silent focusing.

SRS are also offering the same deal. Incredible value. Probably about the same price as the upcoming full frame plus lens will be. Very tempting but then you have to factor in starting over again collecting lenses and 645 lenses are not cheap. On the other hand it is actually available right now

Just beautiful!

Had a Kodak Brownie as child; in my teens a rather nice Yashica with a ring of selenium cells around the lens (not sure of the model - probably an EE). I dropped that on the platform at Manchester Victoria station when chasing the last active steam locos. Next up was a second hand Zorki 4 which was very old fashioned but capable. Then I graduated to a Pentax ME super and started collecting a few lenses. This served me for many years until I got my first digital camera, the superb (and expensive) Olympus c5050 in 2004. The Achilles heel of that one was the on/off switch which failed and had to be replaced twice at over £100 each time. So I gave up on it and bought a K10d, then K5 and K5ii - which is where I am now.

It is an excellent lens and I use it a lot for events and parties. Some complain about the size and weight but it feels about the same as a 16-50 on the camera, so not bad at all. The other frequent complaint is that the Pentax version does not focus well. My copy performs very well on my K5ii but on the few occasions I have tried it on my K5 backup body it has struggled to lock focus in low light.

I have both lenses. They both offer good IQ and are of broadly similar size and weight. It is really a question of which is more important to you - constant f2.8 or greater range. The other issue is reliability. My 16-85 has not let me down yet but the 16-50 has spent more time in repair than on the camera. Even the supposedly new upgraded SDM motor failed in days (I appreciate that I may have been particularly unlucky). So I would advise that if you really want the 16-50 buy new so that you have the guarantee. Personally I am more pleased with the 16-85.

It's worth trying 'auto' mode. I find that PTTL seems to work well for direct flash but is inconsistent with diffusers or bounce flash. Auto usually gives more accurate exposure, for me at least.