Focus on distant objects comes out soft

This is something ive noticed a few times. Im taking my 50L, something like f/2 focus on a subject 10 meters away. The image comes out soft even thought i micro adjusted it. It focusses properly at distances like 2-5 meters but everything more distant comes out soft. Its not even that i can see a part on the image which is in focus, its absolutely everything soft. Then again its the 50L so its a bit a special case. But why dies this happen also with my 70-300? Exactly the same, tack sharp wide open and at normal distances, but everything after 20 meters comes out not as sharp as id wish.

Any advices?

Shutter speed too slow?

BrickR wrote in post #17078295
Shutter speed too slow?

Definitely not. Was shooting the 50L at 1/4000s because it was sunny (hebce stopped down to f/2). The 70-300 was shot at 1/800s and it also has IS.

What do you think, could it be because my hands are so steady that the IS is counter-productive?

Which camera? Or are they both doing it?

speedync wrote in post #17078341
Which camera? Or are they both doing it?

I am such an idiot. As you say i just realized ive used the 70-300 on my 650D. Well the rebel has no MFA so most likely its a bad combination of camera lens. Ill try it again with my 6D.

But hows it possible for the 50L on my 6D not to produce good results. I mean i cant find a sharp spot on the image.

davidfarina wrote in post #17078354
But hows it possible for the 50L on my 6D not to produce good results. I mean i cant find a sharp spot on the image.

Well, I see it like this. It, the camera, is not 100% accurate 100% of the time in AF'ing. When you start shooting at f/1.2- f/2, the plane of focus is very thin, and the cameras AF sensor can mess up at times. It will sometimes lock onto something way different than what you placed the focus point over. Usually something with far better edge contrast than where you placed the AF point. I've noticed on my own camera, that point is sometimes nowhere near the selected point. Like diagonally opposite where the selected point is. As, you've noticed, sometimes it just plain gives up. If it does it all the time, or with alarming regularity, something is not quite right, out of spec, or damaged. If it does it just occasionally, then I'd suggest that that's just life. Joys of shooting at large aperture.

speedync wrote in post #17078369
Well, I see it like this. It, the camera, is not 100% accurate 100% of the time in AF'ing. When you start shooting at f/1.2- f/2, the plane of focus is very thin, and the cameras AF sensor can mess up at times. It will sometimes lock onto something way different than what you placed the focus point over. Usually something with far better edge contrast than where you placed the AF point. I've noticed on my own camera, that point is sometimes nowhere near the selected point. Like diagonally opposite where the selected point is. As, you've noticed, sometimes it just plain gives up. If it does it all the time, or with alarming regularity, something is not quite right, out of spec, or damaged. If it does it just occasionally, then I'd suggest that that's just life. Joys of shooting at large aperture.

It is quite a time ago since ive noticed this on my 50L, but if i recall correctly ive also tried manual focus and didnt worked out a setting where my subject was sharp. Clearly it would not come out as a great picture because the subject was too far away and would be very small, but i had no time to change lenses and id rather have it small than no picture or as soft as ive got it...