Hi, I'm new to this forum, so sorry if I ask something what has been asked. I searched for similar problem, didn't find it. So I have a Canon RF 200-800 since more than a month, but yesterday I really used it intensively and recognized that there is a major issue, probably with the lens. I have the Canon R5 attached to it. Every picture I take is just so unsharp. I could even say it's unusable. First I tought maybe something with the camera, but no, all my other lenses are sharp as hell. I also tested it with the cheap 500euro 100-400 lens and it was sharper! Even if I zoomed in, it was a lot sharper than the 200-800. I have seen a lot about the heat stuff, but I have made over 2000 pictures in multiple occasions. Not one picture I can say, I'm pretty happy about. Zoomed in at 100%, all images are soft and blurry. I wouldn't know how to discribe it differently. Friend put it on the RP, it's the same problem, so it's for sure lens related. There is nothing on google that I found what other people may have experienced.
Well you have a shutter speed above 1/1000 so I can rule out hand shake being an issue. Looks like you may have got a faulty copy, that happens once in a while. I would return if they still allow at the shop. Otherwise its less than a year old and canon should fix for free.
as a rule i test every new to me lens i get, be it second hand or unused for critical sharpness at home under test conditions target is usually a cereal box or bank note on a tripod with 2 sec timer, 100 iso etc if it fails there then its going back this rules out in the feild errors and inconsistent settings due to changing light etc
I also seem to have a problem in that AF commonly focuses just behind my subject. Can this be calibrated for in camera?
Specifically front/back focus is not a thing in mirrorless, you use the same sensor to focus as you do take the image, where with a DSLR the focus was taken off a prism and mirror so micro adjustment in camera was available to to align with small variation in the lens. Focus shift can happen as you shoot wide open but is very uncommon you can read up on it. I said it last summer it seems like you have a fault copy you should have returned right, did you keep the same one and continue to have issues? $2000 is a lot to drop on a lens and not return or replace under warranty right away. This is on Canon to fix, it should be easy for them to diagnose if it is easy to reproduce back focus in specific scenarios. You are not the only one with focus issues on their new 200-800... https://focus-on-photography-forum.net/threads/canon-rf-200-800mm-f-6-3-9-is-usm.255/page-13
