Weird Focusing Issues - Panasonic ?

Adrian Harris wrote:

PS. Photos now added in post above

Okay I have been doing some more testing tonight with just the GX8 and the 100-400 and have learned some very interesting things that can now shed some light on the weird random 'focusing' problems that I have been getting causing blurry/soft shots.... 
1) If any of you have studied the example photos I have posted just above in the thread, you will notice in the very blurred shot of the people on Dartmoor shot using the GX8 and 100-400, that the people were walking, not stood still. Well after much testing it appears that the stabilisation can get confused if half the image appears to be moving in a random manner. 
The GX8 + 100-400 stabilisation is seriously awesome most of the time, but tonight trying different things, I noticed that when photographing some sea shoreline fishermen, when half the frame was a rough sea and the other half still beach, the stabilisation was not happy or performing well. Yet as soon as I swung to a lone figure on the beach it was rock solid. So that random motion in a large part of the frame could partly explain why the group of walkers were causing difficulties. yet a single person walking doesn't.

2) Next: I had the good fortune o speak to a meteoroligist tonight whose job it is study optical clarity in the atmosphere and asked him why my sharp lens produced softer and softer shots as I shoot subjects further away, and he simply explained 'well it would'. 
Apparently many factors come into play.... Particle pollution and moisture particles in the atmosphere cause a reduction in contrast and diffuses light, so edges at a distance will be soft, just as if looking through an opaque window. Also air shimmer due to temperature gradients will also cause distorted images and this can vary moment to moment. And coincidentally he had recently been studying nature photography using long lenses, and it is a know problem. The conclusion was that no matter how big a lens you have, for image quality, there is no substitute for getting closer.

Well I must say I feel much happier now having an explanation as to why near and mid range results were amazing, but my long shots were so very random.

I am still a bit puzzled as to why about 20 shots in a row of a perched hawk 10feet away were all soft, yet all of the shots of bird before and after were perfect. 
Someone suggested that it may have been due to using a much to small focusing square on an area of no contrast whatsoever (it was on the completely white belly feathers of a hawk) thus giving the contrast detection absolutely nothing to lock onto.

Well I hope that info helps someone.