Wonderful

With all this love for the 10-20 I feel I should stick up for the 8-16, it's really a magnificent lens, but I can't honestly compare it because I've never used the 10-20. I won't deny it's a little chunky - up until I got the DA* 50-135 it was my heaviest lens - but I'll also say I've never regretted carrying the extra weight in my bag. With the minimum 8mm focal length this lens can capture images no other lens could. It's also produces lovely vibrant colours and is crazily sharp for such a wide lens.

Very good, generally speaking. Haven't used Clifton so can't compare.

I'd have to join the consensus in that the DA 55-300 is an astonishingly good lens for the price. It produces images with a sharp, crisp look that is on a par with much more expensive optics. It has decent bokeh, too.

I also have the (more expensive) 18-135WR and the 55-300 is noticably much sharper, and just produces better looking images generally IMO. Worth the effort of swapping out the WR and sticking the 55-300 on your body if you want to shoot anything at 55mm+ (weather permitting, of course).

Bit pricey for me in any economic climate. More pricey than all the rest of my camera gear put together, in fact.

I would agree with this, and point out just in case it wasn't staringly obvious that quadrupling the number of pixels on your sensor is not a practical option unless you possess a magic wand - especially if you already have the highest density sensor available for its size (say a D800).

...Expanding on the above my problem with the whole 'there is no advantage to smaller sensors' argument is that it only works when reduced to a purely theoretical level. For example, to requote the words I quoted earlier:

This is absolutely true in theory, no arguments there. But so long as the larger sensor with sufficiently high pixel density to achieve this doesn't exist, the theory is of no help whatsoever to an actual photographer using actual equipment to take actual photographs.

In real life, here and now, to a photographer in the field, the advantages of smaller sensors which have come up in this thread are perfectly genuine.

Around 360 megapixels, roughly.

In a way, however, it is an advantage of a smaller sensor. This has to do with imperfections in the manufacturing process. Manufacturing a 360 megapixel FF sensor is impractical because at such high densities the rate of flaws is such that practically every unit you produced would be defective. By reducing the size of the sensor the number of defective units is reduced to an acceptable level.

The sensors are manufactured on a big 'slice'. Think of it as being a bit like cutting little squares out of a large slice of swiss cheese (the kind with holes, of course). If you cut out largish squares, say twice the size of a postage stamp, pretty much every one will have a hole in it somewhere. However if you cut out tiny little squares you will get a far higher proportion of hole-free pieces.

So you could say that higher pixel density is in itself an advantage of smaller sensors, at least with current manufacturing processes. This may change as better manufacturing techniques emerge.

I wouldn't really expect identical exposure results with the K-5 and K-01, since DSLRs use a dedicated sensor for exposure metering, whereas mirrorless cameras use the actual image sensor.

I may be out of date, but last time I looked (no more than a few months ago) the highest density FF sensor available in a current model camera was the Nikon D800's 36 megapixel monster. If you take an image from that sensor and you crop it down to the size of the sensor on the Pentax Q you will be left with (approximately) a 1.2 megapixel image.

Now arguments about resolution and image noise etc. notwithstanding, I'm willing to bet that if you printed both images at A4 size, the one taken with the Q (12 megapixels) would look a hell of a lot better. The cropped D800 image would probably look like you built it out of Lego bricks.

It's hardly the same net effect.