Didn't read every word on the thread but these come to mind.
If you haven't already:
Check to see if you need to calibrate/sink/reboot etc. your lenses with the new body. Go to the Canon website, they should have info. Also check for firmware updates related to your body and lenses.
If you haven't started yet, use "focus peaking" (ie. digital manual focus) for all your landscape shots and make sure you are using a high enough aperture/Fstop setting like f11-f16+ to get the best depth of field unless you want short depth of field. This is where focus peaking comes in handy so you can see what you want to focus on and then determine depth of field accordingly.
Once you have all this figured out and you have your camera mounted on the tripod ready for the shot, another trick is to set your shot timer (usually 2 second +- etc.) press the shutter release and don't touch anything until after the shutter releases. The camera will then take the shot off the timer with no vibration from you, and hopefully no wind.
Keep in mind pixel count really isn't as important as you might think with full frame except for enlargements like big poster size and up. Many professional shots with incredible sharpness have been made with camera bodies under 12 mp.
If you still have the MK III do some side by side comparisons with the two bodies of the same subject with the same lens/settings using the focus peaking etc. and see how it goes. If there are still issues then it may be time to contact Canon and see what your options are.
Last edited by SBTCO; 03/16/22.
