Which long zoom?

Yes I have one and have tried it on the 60-250mm. It's rather strange in that it works well on my F* 300mm f4.5 but affects the 60-250mm just too much for me (I really do like the IQ of the lens and anything that degrades it is not worth using imo) .. even with my K10D I would rather crop than use the teleconverter with it.

I would expect the 60-250mm to walk all over the 150-500mm though, even with a 2x crop. It is a superb lens and if 250mm was as far as I needed then I would just use that but the 100-300mm is more versatile for my needs (especially with the 1,4x matched TC).

Anyway, at the moment I can afford to keep both .. when I can't it will be a hard decision on which to keep .. but I suspect it would be the Sigma, especially if it focuses faster on a K-7.

I'm with you Mike on the 60-250 + TC - mine will often take 3 or 4 attempts to focus and the IQ is significantly reduced. It's a bit like buying a Ferrari and putting re-treads on it.

I have found the crop results different though. I have got shots which have come out better with the 150-500 than a crop from the 60-250 (or even my DA*300). The Sigma seems to like good light.

I must admit I haven't tried doing any heavy cropping with the 60-250mm and comparing with the 50-500mm as I usually take both out with me (unless its a dull day then the Bigma stays home because, as you say, the big Sigmas need good light).

I really would like to get hold of a 150-500mm and do a comparison with the 50-500mm for myself but if another lens arrived on the doorstep then I am 100% certain I would be living in the garage.

IIRC user 'brandrx' on DePressingREVIEW (dpreview) website has compared a lot of the long lenses available for Pentax, might be worth a look.

PS get it delivered to your work "goods in" dept

Taken tonight hand held with the Sigma DG EX 100-300mm f4 and Sigma 2x teleconverter. Tried with the Pentax DA* 60-250mm f4 and Tamron 1.4x .. have to say there was no contest really.

That's a cracking shot Mike.
Have you tried with the bigma tonight?

Not bad at all Mike. I tried to take a a hand held shot with the 150-500, but I have a damaged rib and could not so I had a go with my rubber tripod.

[IMG]http://i217.photobucket.com/albums/cc222/Oggy3323/IMGP5020.jpg[/IMG]

Taken with the Bigma at 500mm .. again hand held.
Would love the extra MP of a K20D or K-7 and live view to really nail the focus.

Thats a great shot with the sigma DG EX 100-300mm f4. I have this lens and not really used it much yet. I have the 1.4 TC but how do you find the x2, is it still pretty sharp?

Had a go with my 60-250 a bit earlier..

[IMG]http://img37.imageshack.us/img37/2461/60260600x600.jpg[/IMG]

That's not bad at all.
Hand held or tripod? .. I presume on its own with no teleconverter.
That must have been quite a heavy crop .. it stood up to it well.

I havent used it much as I have only had the lens a few weeks and the weather has been carp but if the Sigma 70-200mm f2.8 and 2x is anything to go by then it should be pretty good. I mostly carry the Sigma 1.4x around with it but thats at Sigma being drained of coffee.

Thanks, yes I was quite pleased with it. Hand held without the teleconverter so quite a vicious crop to be honest.

I tried the Tamron converter and yep a bit of a disappointment (see below)

[IMG]http://img37.imageshack.us/img37/6133/60250withtamronx14.jpg[/IMG]