I would suggest to everyone that even if you don't have a K-1 it would be prudent to have the modification done in case you wish to sell or trade the lens. And will Sigma be modifying their K-mount at production stage to avoid this?

No, but I suppose this isn't a warranty issue.

Took mine into the local LCE today, be interesting to see what Sigma do with it as I will be very cautious about using it again. Luckily the mark on my camera body is barely noticeable so i won't be letting Sigma treat that as well.

The Latest Posts right says it's an update on the K50 -does that mean a replacement? If it's in the same price range as the K50 was then it looks pretty impressive, you can't say they are not trying. Pentax needs features like these to distinguish from the competition, I was in LCE this morning and the bloke said he hadn't sold a Pentax in 18 months (had he even offered one?) and there is a generation who haven't heard of it; not surprising as the only K-1 he had was in it's box under the counter along with the others. Pentax now has the products, time for big full page advertising like Olympus.

Sorry Jon, and I thought I was being witty and original! Hope it was taken in the tongue in cheek manner it was intended.

A lot of comments are about the cost, and yes it is a lot to find, but I think Pentax users have been spoiled with brilliant cameras for less than £1000 and lets hope they continue to be. Just take a look at other manufacturers' ranges and nearly all their FF cameras are above this figure and I find it surprising how many times I see £2000+ models featured in so-called amateur photos in magazines and competitions, including junior sections.

These are fabulous images and much much better that I have achieved through a scratched passenger window but while you are snapping away who is controlling the plane?!

Thanks for the feedback, and your generous offer Jon, but I have just spent about £55 on the Marumi so am unwilling to switch now! The examples are great, and dare I say that the quality of both the Raynox and Marumi are able to give outstanding results from such a modest piece of kit. I only came across the Marumi brand recently in a photo shop when comparing polarizing filters and it seemed the best available there. Of course large contributing factors are the lens it is mounted on as well as the skill of the photographer as seen above.

Marumi call it a close-up lens filter, which they produce in four versions; +3, achromats in +3 & +5, and a +10. The achromats have 'multiple lenses', as John says to reduce aberrations. Not the cheapest and prices vary with thread size but first impressions are good. If you are interested: http://www.marumi-filter.co.jp/en/product/05/

PS here is an informal review using one of these on Pentax: http://christinewiddall.co.uk/marumi-achromat/

I know it's not a filter but to keep referring to it as "the magnifying glass that fits onto a lens" is a bit of a pain and doesn't Google so well!