@Kuckel from your deleted comment: "f you are standing far away, so you can use 100- 200mm, you would be fine. Aperture is not the only thing creating DoF you know. " You've fallen into the same trap as the OP - if you have the same framing and the same aperture, you get the same DoF. Hence your 200mm f/4 will have deeper DoF than 50mm f/1.8.

@RyanFromGDSE this is why we downvote and close rants rather than answering them :-) photo.stackexchange.com/questions/83711/…