I’ve been trying to work this out but I can’t quite.
85mm f1.4 looks great
70-200 f2.8 @200mm looks great too (better?)
If you crop 85mm to 200mm you would get 200mm f3.3 equiv. So the 70-200 is actually better.
Ok so 105mm f1.4 exists… That’s 200mm f2.66 equiv. 135mm f1.8 is the exact same equiv. But you have to crop (not ideal).
Is there anything better still?
Does subject distance matter? Maybe with a 50mm f1.2 but with you physically closer depth of field would be more shallow? Probably not.
I don’t care about having the whole car in focus, I just want critical focus on one part and a super dramatic look.
Depth of field is a factor of the aperture selected, and nothing else. But to make the subject appear the same size when using crop factor lenses the subject needs to be further away from the camera. DOF increases with subject to camera distance (focal length) so cropped bodies / sensors appear to impact DOF because they are shooting at a longer focal length to achieve the same look. That’s one reason why cropped systems struggle to get as good bokeh / subject separation as full frame systems.
There are other factors regarding sharpness that could be at play. Most lenses have a sweet spot for sharpness at a particular f-stop (or focal length if it’s a zoom lens), which is not usually wide open.