For me the lenses are completely different. I have been in many situations where it' s impossible to 'zoom with your feet' and so a lense such as the Tamron 17-50 is an imperative. The fact that it is so sharp means you are not going to lose anything over the 35, and usually (excepting Cabstar's excellent portrait of the girl) they don't fulfill the same function anyway. It is the versatility and sharpness of the Tamron that wins hands down for me.

There is a great thread on the other forum (not sure whether people mean DPR or PF here but anyway I mean PF) that has a slew of fantastic shots taken with the Tamron 17-50. The new Sigma 17-50 (not the older 18-50 macro) has been tested with MTF figures that exceed both the Tamron and 16-50, though how much sharper you need to be than the Tamron (and the Sigma is more expensive) I don't know ! The Tamron 17-50 is a fantastic lense.

I've just been to this new electronics shop in downtown Shanghai to take a look at the lenses. They didn't have the Sigma 70-200 there but I was able to look at the larger Sigmas in CF mounts (too heavy and unwieldy for my intended use) and try the two Pentaxes on my K5.

BTW this shop had 43 DSLRs on display that you can handle and shoot (all with different lenses attached) of which 16 were Pentaxes (K5, Kr and Kx) - pretty good exposure right there, in fact I think there were even more Pentaxes than Canons. I really liked the D700 and also the D300s - they felt better in the hand than the 7D whose dials felt a little flimsy compared to the K5's. The D7000 felt awful as did the 60D, IMHO.

Anyway I'll put up some shots later but IMO the D*300 felt much nicer in the hand than the 60-250. I understand what Gwyn meant when she said the Bigma was easier to hand-hold than the 60-250. I think it's the placement of the zoom ring, it could take some getting used too - that was it's only 'fault' though.

However I have to say I still loved the 60-250, the AF didn't feel slow and even in the shop at 6,400 ISO both the *300 and the 60-250 both locked focus quickly and surely without any drama. Both were easily hand-held.

The DA*300 was though, an undoubted step up, the AF was totally silent and a little faster than the 60-250. Shots were a little sharper too - tiny details clearly visible on small articles located on the other side of the shop (60 yds away - the shop is 5 floors of 3,000m2 per floor) ! It just called my name. Decision made. DA*300 it is. And the 60-250 goes to the top of my LBA list, instead of the Sigma 70-200, and can wait until the Summer to join it's brother

Thanks for everyone's contributions - next week I'll go and try out the DA*300 / 60-250 / 150-500 / 50-500 & Sigma 70-200 in hand. I'm sure that will help me make a decision !

The noise advantage is a very good point. It may not be necessary at a sports event but today I was just 10 yds (metres) from a Kingfisher and luckily the 55-300 was already focused on the approximate spot the bird landed - if not then the focusing noise from the 55-300 (it's noisy !) could well have frightened the bird before I got any shots off at all !

Thank you Guys n Gals for your advice and contributions to this thread.

I just can't make my mind up on this. I have had another idea : go for the DA*300 now and then add the Sigma 70-200/2.8 HSM in 3 month's time. A two lense solution rather than one - what do you guys think ?

.... and there is a FA 300 going here for just under US$1,000 too ! *pulls hair out*

Thank you for commenting Womble - that makes three of us

Excellent ! Very cool indeed ..... and Yes, very Roger Dean ish !!

Lovely ! Do you have fluorescent plants ?

#3 for me too.

#4 & #5 for me ! Please number your images in future - makes it a lot easier for everyone