The H4D is simply an H3D with a silly new AF feature. The H4D still has only one AF sensor.
There are two models: the H4D-60 with 60 MP, available in January 2010 for about $43,000 (28,995 €), and the H4D-50 with 50 MP for only about $29,000 (19,995 €), available by March 2010.
These were both announced in September 2009.
True Focus with Absolute Position Lock
The Hasselblad H4D's silly new feature is work-around for the fact that it has only one AF sensor. Most people never noticed these past 50 years that if you point the camera in a different direction to compose after you focus, that you really need to set the focus distance to 1/(cos θ) to get the very best focus.
Since the camera is focused on a plane, if you point the camera in another direction, this plane now slips behind your subject. For example, if your subject is 10 feet (or meters) away, and you turn the camera by 10º because you didn't have an AF sensor where you needed it, in a perfect world, you really should reset your focus to 10 / (cos 10º) = 10 / 0.985 = 10.15 feet (or meters).
This has never been a big deal, since telephotos work at small angles of view so the distances don't change much, and wide lenses have such deep depth of field that it doesn't matter either.
Even when it might matter, many lenses have curved fields which make the problem go away.
The H4D always has to be jacked around between focus and shooting since it only has one AF sensor, and since it has such insane resolution, this feature might come in handy. It's still not as good as using multiple sensors, since the multiple sensors of other DSLRs automatically compensate for any curvature-of-field in the lens, but it's a start.
The H4D system, pitched as True Focus with Absolute Position Lock, uses motion sensors to detect by how much you've rotated the camera to recompose. Wouldn't it be nicer if you didn't have to recompose at all? That was the emancipating thing behind Nikon's new 51--point AF system in the D3: for the first time ever, I can focus-in-place and save the maddening recomposition step.
Phocus 2.0 sophtware
The H4D comes with new Phocus 2.0 sophtware included.
Hasselblad claims that you'll waste an average of 15 minutes trying to learn it, and that it does pretty much what you already can do in Aperture, Lightroom or Capture One.
I don't know if Hasselblad's claims for how long it takes to figure out are how long it takes us on our own, or with a Hasselblad trainer showing us in person.
The sophtware corrects HC/HCD lenses distortion, vignetting and chromatic aberrations.
More Information: Hasselblad.
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