I had both the 12-24mm and the 15mm and sold the 15mm because, lovely little lens that it was to use, the zoom was so much sharper at f4 throughout the range. The 15mm needed to be stopped down to f8 to get properly sharp, as all the magazine tests confirm.

I found that if you didn't need wide apertures,the 18-55 kit lens stopped down to f8 was superb. I only changed mine because I wanted a wider angle but looking back, for what I got for it, I should have kept it.

But back to the OP, the Pentax 60-250mm is about the best zoom I've ever used when set to 135mm and over. At 60mm it's less so, though still more than acceptable.

Yes, I knew that was what you meant and was backing up your comment with personal experience.

I bought a Sigma 50mm f1.4 from Microglobe in Bloomsbury a couple of weeks ago, decent price at £315.

On getting it home I did what I normally do with new lenses and shot a sequence of pix of a neighbour's rooftop with my K5 and the new lens wide open and the focus adjustment from -10 to +10. The Sigma needed an adjustment of -7 for the sharpest image.

Over the next few times I used the lens, I had a high proportion of fuzzies so did some further tests. Basically, the lens focus was inconsistent. It front focused sometimes, rear focused at others. It's always difficult to get good focus with such a wide aperture lens but at a certain point you realise there's definitely something wrong.

Then I researched a bit on the web and it seemed there were problems with examples of this lens. I thought maybe I'd swap it for the Pentax equivalent (55mm, a lot more expensive and with less good performance according to the tests). Unfortunately, according to various testers there are focus problems with this lens too. Must be something to do with the wide aperture, I suppose.

Either way, I took it back to Microglobe, where they suggested I bring my camera in. They had four more examples in stock and I could try them to find one I was happy with. I duly did this, taking my iPad and camera adaptor with me to check the results.

The first lens I tried was perfect, focus smack on everywhere, wide open or not. Having used it for a couple of days now, I'm very happy with my choice. It is astonishingly sharp at f1.4 as the mag tests suggest and at f4 crisp right across the frame.

I thought that was a nice touch at Microglobe, too, to let me try different examples until I found a good one. The original is now on it's way back to Sigma for re-calibration.

I now have a couple of Sigma/ Pentax lenses, this one and the 105mm f2.8 macro which on side by side testing with the Pentax 100 I bought in preference.

I used to do a lot fo work for Paul McCartney in the 'Wings' days and signed a contract agreeing that copyright belonged to MPL (His business holdings company). It also stated that any unauthorised use of he images would be the responsibility of the photographer.

This is a pretty standard contract for high level entertainment people.

The work flow was that after shooting the pix, I would messenger the film to a trusted lab and when ready have them messengered to wherever Paul and Linda were. We would then arrange a time and place and go through the stuff together.

After selection, the material would go to Gene Nocon's place in Coventry Garden for printing, duping etc before being shipped over to Tony Brainsby's office in Chelsea for Tony to distribute as necessary. Thus, there was not much scope for misuse on my part. In practise, the deal I had with the McCartneys over payment would make you a fool to abuse it, even apart from moral considerations.

It is most unlikely that any photographer would be allowed copyright over something like the Presley wedding. The value is not in the pictures but the image of the artist. Presley's management would have been idiots not to have capitalised on the commercial value of these pictures and whatever you might think of Col Tom Parker, an idiot he was not.

The 15mm isn't really sharp until stopped down until f8, as I found and the reviews confirmed. I found my Pentax 12-24mm so much sharper that I preferred to use that to the 15 though it is a very nice little lens to use.

The 70mm is a superb lens, as sharp as any I've used.

Beware the circles of confusion, eh John. First time I've thought of that term in a while.

There is something fishy about this.

I use Sigma 105 2.8 macro and am very happy with it. Very good on GP use, too, a little bit like my old 180mm 2.8 Nikkor that I used to use for all my concert stuff.

I had the 15mm and lovely as it was to use and nicely as it is built, it is not very sharp until stopped down to f8. My observations were in accord with all the tests I read, too.

Since I also had the. 12-24 zoom and since it was so much crisper, I found myself never using the 15mm so I flogged it. Happily, for more than I paid for it

Lovely little lens to handle, though.

I'm surprised everyone discounts having two cameras for different purposes.

I have a K5 Pentax and a Panasonic GF2 on which I use the 28mm lens for keeping with me at all times. This combo is tiny and will fit in a shiirt pocket.

In practise, I use a 1600px width screen to view most of my pIx so the GF2 simply means I throw away fewer pixels from the 12mp Pana than the K5. I use the K5 for more professional work where versatility is most important. But up to 400iso pictures from either camera are indistinguishable. Especially given the superb quality of the Panasonic lenses.

The controls on the Panasonic are neither fiddly or easily nudged, by the way. The K5 is great but the best camera is the one you have with you when a pic presents itself.