Well that stinks. But I think the real problem is not that the Otus is manual, but that all camera manufactures (including the MF guys) did away with real focusing screens.
Why? I would love to know. When I bought my first digital camera, I was so disappointed that there was no split prism and ultra sensitive ring (around that prism) on the focusing screen.
Hi Joe,
For lenses with an aperture that is wider then f/2.8, one needs to use a different focus screen. The regular focus screens do not show any difference in DOF for apertures wider than f/2.8, it's only when you stop down to something narrower that the DOF preview will actually show a change. Split prisms and micro-prisms are also made for specific apertures, otherwise they e.g. go black. The fact that wider apertures do not effectively show a narrower DOF, makes manual focusing harder to get it spot on.
My EOS 1Ds Mark III, like the other Series 1 models, has interchangeable focus screens. I use a special focus screen for wider apertures (the sort of fresnel like structure allows even brightness across the screen), and it really makes a difference, both in focusing manual focus accuracy and also in judging the actual DOF effect in DOF preview mode. The only drawback is a slightly to significantly darker viewfinder image when narrower aperture lenses (f/3.5, f/4, f/5.6, or when combined with a focal length extender) are used. However, despite the darker viewfinder, manual focusing is still more accurate (if there is enough scene light to judge).
I doubt if the 5DS / 5DS R will have interchangeable focus screens, but there are modifications for the current EOS 5 models available on the internet from folks who cut down the screens from the 1 series to make them fit, with DIY instructions and a screwdriver + shims to retro fit it in an EOS 5 series model.
Besides that, it also helps to get the AF Micro Adjustment spot on for the wide aperture lenses, because that will allow usable focus confirmation lights/beeps. Combined with the extremely shallow DOF, that also works well, because shooting wide will not risk focus shift which some lenses show when closing down the aperture.
Cheers,
Bart