Mark_48 wrote in post #10583589
Not sure I understand what you're saying. At f/1.4 you'll see a shallow DOF through the viewfinder, the amount depending on the FL and a few other factors. To be able to view the DOF at anything less than f/1.4 the DOF Preview needs to be depressed to stop down the aperature.
Some focus screens may perform better at showing the DOF, but it won't change what the DOF actually is.
Maybe it's the way I'm reading what you wrote, that I'm not grasping what you're saying.....
from what I've read, and seen shooting my fast primes, the DOF you SEE in the viewfinder looks like what a shot would be if taken at f/2.8~f/4. The lens is wide open, the image will have super thin DOF because it's wide open, but what you see in the viewfinder, even though it's coming through the lens with the aperture wide open, it'll look like an image with a 2.8 or 4 ish aperture. Not sure why, but it's true...
I just tried this with my 85L BTW:
MFD, aperture set to 2.8, hit the DOF preview button and you'll see the image get darker, but the DOF won't change. Same at f/4. From what I was seeing in the viewfinder, @ MFD there was ~4" in focus IN THE VIEWFINDER. Took the shot and looked at it on the screen and the IRL DOF was <1" as recorded. Stopped down to 2.8 and it was still well under what the viewfinder was showing me. f/4 was a lot closer.
Take your fastest lens and try it, but it's something to do with the viewfinder itself.