I'm honestly surprised by the negativity around price with this lens. It's a niche lens with a complex design and near flawless image performance that demands a large price. So be it I say. I'd like to purchase it, but two things will prevent me from doing so in the short term:
- Canon does not have a high megapixel body yet to take advantage of this lens. Granted, there are certainly other benefits such as color rendition, contrast, edge-to-edge sharpness, but my guess is that it really shines with a high megapixel body
- Manual focus through the viewfinder on newer Canon models is an exercise in frustration if you are extremely anal about perfect focus placement. Forget about it on the 5D III, as the viewfinder presents an image with an f-stop well smaller than large ones on prime lenses. I have a 1D-X, but have yet to try one of the focus screens that can be purchased, so maybe I can go that route.
Regardless, I find this thens very intriguing and hope to be able to rent a copy to try at some point. I will reserve any judgment on price until then.
As MP goes up, difraction limitations increases...so the pros and cons of high MP cameras on a 35mm format is unkown at the moment.
It's true, the 5DIII and all Canon stock screens render a DOF of roughly f4...which is a million miles away from fast primes (f1.2). For f2.8 glass, it's not so important but for fast primes, it needs to be worked around. The 1Dx, 5DII and 6D have interchangable screens and when fitted with a "g rated" fine focus screen, the actual DOF can been seen in the viewfinder...but the screen is somewhat darker (fine if you are using primes). I have found that the Spot AF system (which I think isn't on the 1Dx - please correct me if i'm wrong) is fantastic and nailing a precisely placed point of focus, but it's tricky.
"roughly f4" ? I think it's actually f2.5.
The 1d X have the spot-AF in the same way the 5d3 does, and also an advantage over the 5d3, the ability to set spot-metering to any focusing point.
I have the EC-S focusing screen for the 1d X, but I stopped using it after buying the 24-70 II, and it was indeed tricky, because metering isn't supported so you will be doing a fair bit of compensation.