Certainly if you're getting consistently different results with two cameras and that is the only variable, it suggests that at least one of them is duff.

Forgive a dumb question, but are you using the spot focusing setting?

It's not on 'Sel' with something other than the centre spot selected, is it?

And you're definitely using the green hexagon, not the appearance of the red dot, to tell you it thinks it's in focus?

Other than these possibilities, it's sounding more and more like there's something amiss.

Glad to hear your camera's Ok, Peter.

A thought strikes me... with digital it's now incredibly easy to set up these quick tests, and just as easy to disseminate the results.

A few years ago, when we were all using film, how many would have bothered to look into this kind of thing?

Not entirely convinced. The CA shows green below and magenta above, so the lower one looks sharper, with the magenta above making it look less sharp. But I think the green blur extends as far as the magenta one - or if not it's beyond the precision of the experiment. It's only a 600 dpi laser printer, and ordinary paper.

Quite so.

I find it disappointing that when people understandably worry about whether it's their equipment or their technique at fault, the 'tests' they do to establish which it is are often very poorly designed, and allow no firm conclusions to be drawn.

I'm not saying that DXG is wrong, just that his tests are not conclusive.

Remember - the more unlikely the claim, the more rigorous the test needs to be to prove it beyond doubt.

In this case, the test is trivially simple to do, providing you're careful. Equipment required: chair, tripod, camera.

Ensuring that the focus is extremely accurately in the centre of the region desired is not, however, easy, since it's very easy for slack in the tripod or even the carpet to result in slight movement between the positioning and capturing the test image.

I had a go at this just now. Sadly, it seems I must continue to blame only myself when my pictures are unsharp:




Edit: I should have said, focus was set to spot, and I got the green hexagon when the very centre of the frame was aimed at the "this text should be perfectly in focus" part of the chart, which was stuck to a flat piece of card.

In DXG's case, the chart doesn't seem to be straight in the first one at least, and with such a short focal length lens, it would be a lot harder to point it accurately than with the 300mm I was using. I'd like to know a bit more about his setup before I believed the results.

I'm not entirely convinced. I agree the differing distances of the bank make it look worse than it is, but it also appears to me that the base of the layer of cumulus above the most distant part of the water is not quite parallel to the edge either. Cumulus cloudbases are usually pretty horizontal. Not always, though, so I withdraw the "definitely"

I tried a 0.5 degree clockwise rotation, and to my eye it all seemed a lot better.

I think this is an example of where breaking the rules is the right thing to do.

The way the shape of the tree line is suggestive of the shape of the water creates an almost-line of symmetry that works very well half way up the frame.

Definitely a bit wonky in the first one.

Phew. For a moment there I thought people had been talking...

Thanks. No crowds, though. Here's a bit more of a clue as to the vantage point...

This is from a bit further away - the village of Cerne Abbas. The figures are on the green rounded hill to the left of the village.