The problem with multi point AF on medium format is that placing the points so wide from the centre of the less would very much reduce the accuracy. Especially if you wanted to use a short depth of field. You could argue at tighter apertures that the issue would be dissolved of course.
Hasselblad must be applauded for even trying to address this autofocus issue. I can't see that it would work for me, but maybe it would for others' style.
I was shooting a job last week on the road, and this focus thing again just slapped me in the face. I am amazed that more photographers don't talk about it. Maybe it's just too embarrassing that, in the year 2010, we're still dealing with basic things like keeping the subject sharp, (even when shooting on a tripod, with a non moving subject). My setup, at that time, was a location environmental portrait. I was shooting with an unnamed 35mm DSLR (5d2), tethered, on a tripod. To give you an idea about how far away, I was shooting with a 50mm f1.2, at f8, and the subject was full length, in vertical format, but there was a good deal of room around their body. So in short, the subject was pretty damn far away. You'd think, with f8, on a tripod, with a non moving subject, the autofocus sensor could nail it. I used one of the outer squares for my focus sensor, due to how my shot was locked down, and I was trying to find some constrast in her clothing for the AF sensor to grab onto. Here is the key: You CANNOT trust what you're seeing in the Viewfinder. So many times, it looks TACK SHARP, but you shoot tethered, and you lean over and peek at the monitor, and for, the focus is slightly off. To me, this issue is The Great Unspoken issue about all digital cameras -- the Viewfinder, (even with StopDownPreview pressed), does not match, at all, what's actually rendered into the file.
But the truly scary thing is: I have spent DAYS with my assistant, and we test these cameras's focus issues, sitting there, shooting tethered, looking at every frame. The scary thing is: There is no rhyme or reason sometimes. Sometimes, you shoot a frame, it's tack sharp. You shoot the next frame, everything the same, (on tripod), and it's slightly soft. It's like there's some kind of "autofocus hunting" going on, even though you can't see or hear any hunting going on. Frame after frame. I have calibrated each lens; I have thrown salt over my shoulder; I have even tried religion. But this autofocus sensor thing haunts me. (I gave up on shooting Manual Focus last year).
Back to Hasselblad, here is the problem to me: maybe I'm missing something. I see myself shooting in this way, and it seems like this:
a. Compose the frame. Lock down tripod.
b. Unlock tripod.
c. Find what you want sharp on the subject, (and hope it's contrasty).
d. Put focus sensor then and press some button.
e. Hold down on that button.
f. Unlock tripod.
g. Recompose frame.
i. Unlock tripod.
j. Find what you want sharp on the subject, (and hope it's contrasty).
k. Put focus sensor then and press some button.
l. Hold down on that button.
m. Unlock tripod.
n. Recompose frame.
Over and over and over.
The reason I post this question: Are other people fighting focus too, no matter what digital camera you're using? I'm no fan of LiveView, but on the 5d2, it's pretty damn amazing: double click on the zoom thingie, and you're at 10x, and you focus, and YOU KNOW YOU GOT IT, because you're see what the sensor is seeing. But I am not fast enough shooting people's fleeting facial expressions to actually use LiveView.
It just seems that, overall, the Focus Tolerance for digital is MASSIVELY smaller than for Old Timey Film. So much so that, I just wonder why more people don't fight with Focus, even using AutoFocus. I could put up a strong argument that, with the tiny tolerances of these digital files, that it's clearly time to abandon the Ground Glass, and mirrors, and simply use an Electronic Viewfinder, in order to know that you nailed it.