I believe the 300 is optically bit better. It's PF is much better controlled than on DA*200. If you want flexibility though, than the 200 + DC is better choice.

Yes and no,

Good lens with good TC will be better than average lens.
Sigma 100-300/4 is fantastic lens, I had one for short period of time (gave it up as it had some focusing issues). If I got the focus right, the results were stunning. That lens is really, really sharp from f4. There are many happy campers over on other Pentax forum. Combined with Sigma's own 1.4 TX or good Tamron 1.5 TC the results this lens is delivering are really good.
Now, I've never read direct comparison of this combination to the other lenses you mention, but I believe that 100-300 is part of EX range. Being IF and IZ gives it some advantage over the 150-500 and 120-400 in terms of size and construction.
One option you don't consider, is so called Bigma - Sigma 50-500. Reportedly it's better than 120-400 and 150-500.
Personaly I'd still go for 100-300 + TC. I really liked this lens. It's large lens, but it's worth every penny.

BR
Peter

I think there are two reasons for for higher prices of K series:
a) rarity
b) optical construction

a = K series was in production for only 3 years (only few examples like K24/2.8 have been manufactured for longer) between 75-77. Not many were made and hence they are getting rare.
b = optically many of K series are SMC Takumars with M42 thread swapped for K bayonet. Takumars have alwasys been regarded as some of the finest lenses, period.

Now take these two factors, add the fantastic construction quality (My two K series easily rival the FA ltds I have), durability, full compatibility and you have good recipe for price increase

BR
Peter

thanks for the replies,
I may be selling my soon to fund some WA so just want to make sure I won't go too low

I think here polarizing filter would help, I think that the stones you can see through the water are bit distracting. CPL would help you eliminate them.
But still nice shot

Hi,

I was just wondering, how much is good price for used FA135/2.8 in UK?
The lens is in decent condition, has some scratch on front glass, but it doesn't affect the IQ.
Any ideas?

BR
Peter

Nice shot IMO.
Did you use polarizing filter?

Thanks for looking

Another Londoner.
I've just joined but if "London group" would happen I'd join for sure. Would be up for outings too.
I'll keep an eye on this thread

BR
Peter

Since I'm new around here I figured I'd post some shots as part of my introduction. I took these last week in Putney, London. Any C&C welcome.

BR
Peter