Yes you can open up to f4 but that's often not the 'sweet spot' of a lens (think of the DA16-45mm or FA28-70mm). The aberrations you get shooting wide open aren't going to be made any better by APSC's 1.5x crop either. And if you're comparing two lenses shot at maximum aperture, that option obviously isn't available!

Conversely, to get greater DOF on full frame, you can always close the aperture down. Diffraction is going to be less of an issue on FF as you stop down, and as good as the K5 is, FF high ISO performance is likely to be better too, so there's no disadvantage in this.

The fact that the all-manual Post 50/1.2 is priced that high demonstrates some interest in the sort of DOF it can deliver. But I imagine the results from a reasonably good 75-85mm f2 lens on full frame would probably be better - less prominent aberrations, and 'glow', etc, and you could probably buy such a lens with all mod-cons like AF and auto-exposure.

Now I'm not saying that shallow DOF should be an overriding concern in anyone's choice of kit, but I am just addressing the argument that it is not a concern at all, and that differences between the formats don't exist, because clearly they do.

Ortlieb make padded inserts which you can fit inside an existing bag or handbag. I used one with a canvas army bag.

Pentax will produce a FF when they determine the market is right, no sooner and no later. I don't really understand why you think this would be the 'end of Pentax' particularly when you consider that the investment required would probably be much less than, say, the 645D. You could argue that Pentax might eventually become a niche market, forever being nibbled away at by the mirrorless market at the bottom end, and the FF system market at the more expensive end, if it doesn't address the FF issue.

Algi, do you honestly think Pentax produced the K-01 because they read people wanted it on our forum? I don't buy it for a moment, and anyway, in no way does the K-01 resemble the product most people were talking about. Fine product though it may be.

John is right - you seem to be ignoring the practical context in which people are taking images. On APSC people need to choose a wider lens and move further away from their subject. That is what increases DOF at a given aperture setting. Pictures speak louder than words - so find the two images below both shot at f5.6.

50mm on FF

35mm on APSC

It's always going to be possible to stop a lens down to get greater DOF. It isn't possible to open a 35/f2.4 lens past f2.4 to mimic a fast fifty. You would have to buy something like a 35/1.4 which is exactly why people do just that. Unfortunately these lenses are bigger, more expensive, and generally won't perform quite as well wide open as say a 50mm at f2. Especially as the crop-factor magnifies all lens aberrations.

This is my favourite Pentax prime right now - lovely results right from f2! Get it for portraits - it's very easy to use in Av mode (wide open).

And it's so small! Compared to the Samyang 85mm/f1.4 it's tiny - and so more likely to be taken along with you.

To answer the original question, FF would enable me to capture images with a narrower-dof 3d look at equivalent apertures. That's not quite the same as improving my photography, but I would prefer my images if I could achieve digitally, the same sort of 'look' I get on film. I'm not sure whether the advantages are quite sufficient to make me want to upgrade though. I guess it depends on price! I hope sensors continue becoming cheaper.

I think FF will become more standard for dslrs, while mirrorless cameras will get the apsc sensors and displace the market for entry level dslrs. I also think compact cameras and phones will get bigger sensors as standard - e.g. 1". We're already seeing it. The pixel war is over; the sensor size war is just warming up...

And a Merry Scroogemas to you to, Smeggy!

Good for you, Gwyn! I don't think it was pointless at all.