Touche

I think that remains to be seen as x2 TCs always dilute the IQ - the 250-600 has a lot better than superb IQ so it really comes down to the range you will use most often. If it's 70-300 (and rarely need the TC) then maybe it'll work for the lucky few or pros, However usually people gravitate to the extremes of a zoom so therefore the 50-150/2.8 at one end and an F or FA 400 or more, at the other, makes sense too.

Well that's a much better price than expected ... but still far too much for me to consider when I think what else is out there (even in the same range) that I can spend my money on ! Especially so when I think what can now be done with a slower lense, f4 for example, on a K5.

120-300mm F2.8 : don't see the relevance for 99.99% of us ! It's going to be over US$10,000 and there are better options IMHO, a used 250 - 600 springs right to mind !

I had the 80-320 (gone and good riddance, very soft), then the Tamron 70-300 (excellent lense, very sharp, though prone to PF - although I didn't notice it in 99% of my shots) and then the 55-300. There is no comparison, there is a reason why the 55-300 is much more expensive than the other two, overall it's a much better lense (DA version not the DAL).

BTW - I'm selling the Tamron if you're interested 75 inc. postage in the UK.

You need a longer lense. I'm using the 55-300 now and have tried both the AFA x1.7 and Tamron x1.4 TCs on it (these are two of the very best for Pentax users) for a Kingfisher and other birds I'm stalking this week, but I'm actually having more success with a Tamron BB 500mm mirror, even though it's MF of course, as the quality is great and MF is an absolute joy with the silky smooth focusing of this mirror.

I'm currently saving up for (2 months should do it - once I've sold a few lenses) a DA*300/4 or the DA*60-250/4 as both will crop beautifully and the two TCs mentioned above work great with these lenses (esp. the *300). However I haven't ruled out the Sigma 120-400/4.5 - 5.6 as the reports I've been reading seem to indicate the HSM in the SIgma gives the 120-400 a distinct speed edge over the Pentaxes. The Sigma 150-500 could also be an option as it's only a little heavier than any of those three.

Matt - that may be fine for a virtually static or very slow moving subject but obviously the speed of the movement of a subject will affect the shutter speed required to freeze the action. That's too slow for children. Usually 1/640 - 1/800 is needed and of course much faster than that with some subjects.

Yep, as Mark said. Although it doesn't screw on - it has it's own clip-on adaptor which makes it simple to add to virtually any lense within the range of the adaptor. If you want to get real macro then get the 250 (go to my website below and check out the yellow 1cm long caterpillars - these were taken with a Raynox 250 on top of a Tamron 90 Di. Great sharpness and IQ).

Take your pick from here : http://www.raynox.co.jp/english/digital/d_slr/index.html

These lenses are well under a US$100 and superb value for money. Easy to carry around too. I would suggest you start with the 150.

Sell the Sigma and get the 21mm Ltd !

I was in the same boat as you ... thinking about selling the 43 Ltd. However last year, after getting it out again for a few shoots to see if I right, I decided I couldn't be more wrong. Instead I've just had my daughter take my F 50/1.4 (that's right, no 'A') - the Bokeh Master, over to London, that's going on the market next week.

Now the 43 goes with me everywhere. If you are going to get the 35 then I really would sell the Sigma. The resolving power of the 43 (this has been MTF tested as Pentax's sharpest lense) means you can easily crop away anything you don't need and it's a great low light lense - especially with the K5, I was shooting just this evening with the 43 @ f2.2 and 3,200 instead of using a flash. The Tamron 17-50/2.8 wasn't doing it for me.

You could of course just add a Raynox 150 or 250 to your kit for macro. Those are little wonders with fantastic IQ.

The Tamron 17-50/2.8, whilst a great lense, does often need calibrating. I actually tried 4 models in the shop before settling on the one I have now and that still needed in-camera adjustment of +5. Fantastic lense but you really need to try before you buy.