Sharp Long lenses for my K-30

There is one on this very forum for a good price LINK

Another vote for the DA*300.

don't forget the Sigma 100-300 F4 EX DG but it's rare in the pentax mount. although one did appear here recently.

There have been 3 in the last couple of months ... bit like buses, you wait all day and then 3 come along at once.

The 100-300mm f4 is the best zoom lens in the 300mm range available for Pentax (and it would take a lot to get me to sell mine) but I find it doesn't play particularly well with teleconverters for some reason, even Sigma's own.

interesting to know. so the DA* 60-250 + a TC would be a better bet?

particularly since sigma have apparently stopped making the k mount 1.4x and 2x TC's and isn't the sigma 100-300 F4 getting low for spares regards a repair?

Nope, again I find the 60-250mm doesn't take a converter very well .. although that may change if the rumoured Pentax converter makes an appearance as I would guess it would have been extensively tested with all current Pentax lenses. Until (or if) it's released there isn't really a TC that gives flawless autofocus on DA* lenses.

Hopefully that may change.

So the Da* 300mm would be ALOT better IQ wise than the 55-300mm/150-500mm? (both of which it seems are similar in terms or IQ).. i mean enough to justify the £1000 price tag?

and how does the 55-300 + 1.7x TC compare to the 150-500 looking at sharpness and IQ? which one would u go for if u had to pick one.

Just in case anyone missed Chris's post Sigma 150-500mm for £649 at http://www.srsmicrosystems.co.uk/ PLUS £100 cashback from Sigma! Can't be bad.

The 55-300 doesn't perform well with a TC, but there are exceptions to every rule, it is probably borderline OK with very good light.

If for wildlife shots especially birds you can ignore comments about sharpness not being the overriding priority - it is considered to be the holy grail.(Notwithstanding the usefulness of other factors such as focusing speed)
I have DAL 55-300, Sigma 150-500, and DA* 300. That is the order in price and that is the order I have found to give optimum performance for bird shots. The latter is the only one really acceptable with a TC. All produce excellent results so it depends on your budget and how far up the scale you are or want to be.
Dave
http://www.flickr.com/photos/dcweather/

Anyone have any feelings for how the Sigma 120-400 compares to the 150-500, in terms of IQ and of handling?

I've used a few different zooms in 70-300 range, and struggled with responsiveness (mostly with AF bouncing), so might push the boat out a little bit given SRS have some pretty good deals on. I've got an old 300mm APO which gives a good image but is very hit-or-miss with AF (mostly miss, with the duffer driving it!), a lens which combines its image quality with improved focus would be perfect.

I have a 135-400 Sigma and love it. never used a 150-500 though

Really super lens, I have one and hardly use it but would never sell it!

The DA*300 is a stunner and I can't bare to part with it, but I spend a lot of time running around trying to get back far enough, quite often, I can't.
A zoom will solve that and also show you which focal length you use most often so your next purchase can be an informed one.
Sharpening in post? pah, if your lens is soft or has poor resolution, you're stuffed.

Search the classifieds, both here and on the yank forum. There are quite a few converters coming on to the market at the moment with the new Pentax converter now coming along.

Both are going to produce decent images but not as good as a good quality long prime. As has been said the difference between them is more in price, weight and reach than insignificant difference in image quality.