The IQ certainly stands out, its clear to see. Your shots show off aspects if the performance nicely.

Just ordered now! Great price. Sure its the old model, but I've been considering the Metz options such as 52/58, but like the physical controls more on the Pentax. Also to note is that it offers auto flash control for older lenses through the front sensor, as the Metz units do, but the new updated Pentax guns have lost this feature in favour of a video / modelling light. Thanks for the link

They are all very effective - dynamic and energetic. I would praise in particular the very strong framing, good use of space (have you cropped much?) and I am impressed with how you seem to have got into the right position to capture all the smoke trails from just the right angle. All round brilliant job!

The 2nd Red Arrow one is perhaps the most extraordinary photographically. I think you've overdone the saturation boosting on the 4th Red Arrow one, and I'd suggest a bit more noise reduction on some of the blue skies, just to make them a little smoother (you could apply the NR on a layer and mask out its effect on the planes to retain full sharpness).

yes that would be most creative, although perhaps a bit more effort than our OP was anticipating ...

I think if you could control the flash exposure greatly to reduce it right down to a very subtle illumination then it could work - but frankly this is very limited with P-TTL - ideally you'd be wanting a flashgun with full manual control and a good number of power output steps - I really don't think it will be accomplished with any style in P-TTL.

I agree that flash in general can work to balance our lighting issues. But this is a machine gun bunker, no lighting at all and bright sunlight outside. Does anyone imagine that on-camera flash will make a nice reproduction of the insides of a bunker? I can only imagine a harsh sterile look, like bad Facebook party pictures! The exposure required for the exterior is likely to produce pitch black inside, leaving only the flash to light it ... If it was a more gentle fill flash type situation I agree it might work, but not under the specific conditions described here.

For sure, sounds like a typical high dynamic range scene. If you want both in and out to be well exposed there's no option but to use HDR or shoot two exposures and blend them. Both these techniques need a stable camera with minimal movement between the exposures. The camera HDR takes 3 separate exposures and merges them, so you still need a steady camera. Its great fun , enjoy experimenting!

One question is, will there be any special qualities inherent to some of our current aps-c sized DA lenses that would still be worthwhile even with a load of pixels chopped off around the edges?

On the surface, applying automatic cropping at capture might seem like a pointless waste - why buy FF when you're going to cut a lot of it off. But I guess there is more to higher IQ on a bigger sensor then just additional pixels ...

Also it will help many to make the move - it will be good to be able to carry on with some special DA lenses if they offer what is needed even without the full image circle, and allow you to get shooting while arranging a new lens collection.

Really very nice images here David - I especially love No 2 & 4 - 2 has such good balance with all the 'elements', and 4 has a dreamy high key feel. All beautiful!

Yes a great set, full of interest and detail, sharp and nicely exposed. The ultra-wides work very well even with the distortion which kind of suits I feel. I like your very strong framings, not any wasted space at all! 'Top Floor Landing' is the best of a very good bunch IMO.