Weird Focusing Issues - Panasonic ?

I am trying to get to the bottom of some strange 'blurry' shot problems and need some serious brains on the problem...

Kit: 2 different Panasonic cameras GX8 and G1, plus 3 long lenses: 1 Olympus 40-150 f2.8, 2 Panasonic 35-100 f2.8 and 100-400mm..

Recently I have read here of other people with a GX8 getting lots of apparently mis-focused shots. Up until very recently, either I hadn't or, hadn't noticed!

BUT ... last Sunday whilst shooting a Roller Derby in very poor light, during the second half I switched from a Panasonic 35-100 F2.8 to an Olympus 40-150 f2.8 and noticed that the images on the camera didn't look particularly crisp. I tried lots of different focusing modes - just in case - but still nothing looked great. I was using mechanical shutter and shot from 1/50 panning up to 1/250 shutter speeds. When I got home I literally deleted hundreds of blurred shots in a row. None looked like shutter shock!

I put it down to something I must have done wrong, but...

Last night I was photographing birds of prey in stunning light - with the same 2 lenses, at over 1/2000 shutter speed, with electronic shutter and noticed that frequently I would get groups of shots with the same extremely soft (and unusable) look.  Of course some this was due to panning with fast flying close birds, but many of the worst were of static birds. I think all were over at or well over 200mm focal length ???

So today I went out and have done some testing:  1st I cleaned the olympus lens and took a few hand held shots with the GX8 in the back garden. It seemed fine, so I put it down to possibly smears on the lens. Job done I thought.

But then went onto nearby Dartmoor and with initially GX8 and 100-400 tried to photograph (anything around) some people, a few horses, a seagul on the ground, plus a cow - with Very strange results!!!

Virtually everything photographed closer than 20 metres (20 yards) was pin sharp. ALMOST everything photographed over 50 metres away was very blurry.  Roughly out of every 5 blurred shots was 1 sharp one.  This was in very good light, electronic shutter on, and fairly high shutter speeds.

The dual IS stabilisation was seriously impressive through the viewfinder, but it didn't seem to translate to the shot. As I had a very old Panasonic G1 in the car boot as a spare emergency body, I put the 100-400 lens on that to try again. Through the viewfinder the lack of in body stabilisation was very apparent, but the image results were very similar - 3 duff shots, 1 good shot !

I will try and post a few examples, but as they are on another PC it will take me a while to do and I want to sort out which examples are of most use.  One very strange result - that happened a few times - were a shot of people on the horizon about 1/4 mile away, with only one or two sharp, yet this was at a high shutter speed at F8 and they were all stood in a line.  Now this happened with the 100-400 on both cameras !!

So I have done a factory reset on the GX8 tonight but realise that it was not just on this camera and apparently not just the panasonic lens either, what on earth is going on - HELP!

Meanwhile (as it will take a while before I can show the pix), has anyone else had strange issues like this, I would certainly like any thoughts or comments ?

Below are some example images, all hand held and interestingly the slowest shutter speed by far produced the best results. Although handheld, these have recently been very repeatable tests. I take your point about razor thin DoF and you are right on that score, I have spent a few months discovering that issue and in most cases have it nailed - Many thousands of roller derby shoots taught me very quickly mainly the hard way
But the 100-400 was a whole new ball game, wow and people thought f6.3 was slow, they have no idea. Anyway here are some shots...

Click photo for bigger image: 'lens_test_g1_plus_100-400_typical'. Now I am not surprised this isn't better considering the camera and distance and possibly haze, but ...

Click photo for bigger image: 'lens_test_g1_plus_100-400_best'. This was the best of four shots from the G1 and for 1/4 mile and 12mp I think its pretty reasonable, however ...

Click photo for bigger image: 'lens_test_gx8_plus_100-400_typical '. Virtually all my GX8 long shots with the 100-400 were of this quality. But if shooting nearer objects, then they were most likely to turn out as below....

Click photo for bigger image: 'lens_test_gx8_plus_100-400_closer range '. Most handheld GX8 shots at 20 metres with the 100-400 were of this quality even though it was shot at a slow shutter speed. Because this was at f6.3 not all of the head is sharp, but most of it is and wow, it is sharp.

So I am beginning to wonder if the stabilisation could be partly responsible, in that I am beginning to think that interaction between certain focus areas and certain subjects are causing an upset.  On some scenes it is rock solid, but others it seems to struggle with. I have noticed that AFC is slow to focus and also hunts badly on a still subject without much detail. AFS however is so fast it has shocked all my Canon / Nikon friends. 
Anyway, I shall be interested in feedback and others findings.

PS. I understand your suggestion re use a tripod, and I will try it, but it is strange that I didn't have any issues like this until 2 weeks ago, even at 1/50. And at 1/2500 I wouldn't have expected any problems. But will try it in the next few days and report back.

PS. Photos now added in post above

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.