Howard,
Actually, I believe it is easier to achieve
accurate focus on a tech camera vs. a MFDSLR. It is very much easier to get "pretty darn close" with a MFDSLR. For example, On a Phase DF camera, switch to autofocus and let it do its thing. Or better yet, switch to manual focus and watch the focus arrows in the display. This gets you as close as the AF system can do (and/or as good as
my eyes can see through the viewfinder). However, a calibrated system like an Arca or Alpa along with a distometer is more accurate in my experience. One of the main reasons is the amount of rotation it takes to make small changes in focus. Arca is the extreme case, where you turn until your wrist is tired!
At a recent PODAS event, many of the other participants made comments about how sharp and accurate my images were compared to what they were seeing. I believe this is because of the focus process. The first day I used the Phase DF issued to all of us. Those images were inconsistent in regards to sharpness, yet all at similar apertures and ISOs. I think the Phase camera is pretty darn good, but I have yet to find a camera that can autofocus as well as a precise manual process.
Of course for focusing, neither is as good as real live-view. On my 5DII, I can see what almost looks like moire on the back LCD when it is focused just right at 10x in live-view. So far that is the only system in which I feel confident I am getting everything the system has to offer. Again,
in my experience, this is significantly more
accurate than letting the camera auto focus. Especially with wide-angle lenses.
Dave
The choice of tools to make photographs, like most choices in life, comes down to weighing the plusses and minuses for you and your way of working. I have to assume that the reason why the very top fine art landscape photographers do not use tech cameras is that, for them, the the negatives in terms of making the best images outweigh the positives. These are individuals who come from a large format film background, so I am sure the issues of speed/convenience and the cost of a tech camera are simply not relevant. OTOH, the lack of an optical viewfinder (or useful groundglass) allowing for precise composition is, IMO, a significant issue when you shoot a tech camera untethered. A key part of composing an image is making effective use of the full canvas captured by the sensor. Another issue is the difficulty of achieving accurate focusing with a tech camera. Finally, related to the first issue but still distinct is being able to see through the lens, so you have a real time sense of the perspective of the image as captured by the lens. The wide or longer the lens, the bigger the deal this is, because it is quite difficult to really "see" the same way that a wide lens like a 24HR "sees" the world. (I know I cannot.) It will be interesting to see whether the IQ series of backs helps to overcome these disadvantages. Michael R. is using an IQ180 with his new Alpa.
