There will be a difference between the centre and at the edges, but I'm surprised it is troublingly so. A somewhat better lens in that respect is the 12-24, which at least at the wide end is excellent in the centre and good at the edges (it tails off a little towards 24mm).

But it's probably worth trying to squeeze what you want out of your current lens. Your question about whether or not you need a fast lens makes me wonder if you are using the lens at too wide an aperture (that would explain the noticeable centre-edge difference). I'd recommend stopping down further than you have been, even if (for interiors) the ISO has to increase to compensate. Of course if you're in one of those rare churches that allow tripods, just drop the speed instead.

For the particular purpose you mention, paying more (and carrying more weight) for a fast lens is money/energy wasted.

I have a foot in three camps. I shoot film on a Pentax (Spotmatic) but digital on a Fuji X100T and Nikon (D810), having switched out from a well-loved Pentax K5.

Am I troubled that Nikon will go the way of other well-known marques? Obviously, I hope they don't. Their restructuring, getting rid of parts that don't make money, may make them vulnerable to a takeover. (But as Pentax under Ricoh seem to have demonstrated, that need not be a bad thing.) They are certainly going to have a difficult patch as revenues fall off and the need for innovation and investment continues. If they find themselves seriously squeezing the latter to show profit in the short term, they may well struggle. The point made in the video about them being short on broadly based software expertise rings true -- though the same could be said of other manufacturers, including perhaps Pentax.

But to go back to my question at the start of the last paragraph, I am pretty sanguine about the fate of Nikon. I shall continue using and enjoying what I have and when the time for replacement eventually arrives it will be up to Nikon to have developed something that entices me. If they haven't, or if they are no longer around, I may again find myself the owner of two Pentax cameras.

Is it possible that it was supplied to the shop as a body with kit lens and that to supply your order of body only, the shop split the box (as it were!).

But you should perhaps ask the supplier to explain ...

As inspiration, have a look at Stuart Holmes's Photographing the Lake District (2014). Kh's suggestion of Castlerigg Stone Circle is a good one. Or (if you're driving) Ullswater is within reach and offers a host of opportunities..

Seemed to me a balanced appraisal with some statistical significance. The authors of the survey make clear the limitations. 500 responses out of 5000 is way over the norm as a response rate for this kind of exercise.

For those interested, who haven't already seen it, here is Nasim Mansurov's review of the 645Z: https://photographylife.com/reviews/pentax-645z . He finds plenty to like about it. His reservations? The autofocus and the lack of an electronic shutter ... and partly because of a hand injury, the bulk and weight of the camera. But he loves the quality of the output. His suspicion is that the relative success of the camera has tempted Fuji to enter the fray (early next year) with their mirrorless camera carrying the same size sensor as the Pentax.

Happy to be corrected. I hadn't thought of the benefit of stabilization of the viewfinder image -- certainly useful, I imagine, for longer lenses than those I tend to use.

Yep, optical stabilization built into a lens intended for a Pentax camera would be redundant, so third-party lens-makers understandably leave it out of variants of their lenses designed for attachment to a Pentax (while frequently building OS in to variants destined for Nikon, Canon etc).

Whether it is worth 'upgrading' to a K1 from a K5 depends to a great extent upon how you want to present your photographs. 16MP is ample for most purposes. If you mainly view photographs on a screen, moving to full frame will probably not transform your experience. The K5 also produces very decent prints at A3. The definition of a K1 or any other full-frame camera will offer greater scope for printing large (provided a good lens is attached). Of course the K1 has bells and whistles unavailable on the K5, but fundamentally you are likely to notice an incremental rather than marked difference in your output solely as a result of buying it.

Smugmug? Zenfolio? Neither UK sites, but fulfilment is local.