Many people seemed puzzled by Hassleblad's phrase "full frame 48mm format", including some who express the strange idea that "full frame" must necessarily refer to a film format, in this case the 42x56mm "645" format of previous MF systems.
Here is what Full Frame (as opposed to "crop frame", "partial frame") means to me:
The camera system is designed and optimized for the format of the sensor or film frame (in this case about 36x48mm) and does not impose a crop on components designed for a larger format. In particular,
- The sensor does not impose a crop on the lenses or lens system, and so does not hamper wide angle coverage.
- The viewfinder does not force one to compose using a crop of the full image that the VF is designed to produce, through crop lines or a VF mask.
The H3D and HCD lenses achieve some but not all of this:
- The lens system as a whole avoids any loss of maximum wide angle coverage to cropping, as the camera records the full FOV of the widest lens, the new 28/4 HCD, which is as wide as any previous Hasselblad 645 or 6x6 format options AFAIK.
- The new HVD90X viewfinder covers the "48mm format" frame of 36x48mm, matching what the sensor records. All previous digital MF systems including previous H system cameras with the HV90x VF have a sensor crop relative to what the VF shows. The new "D" version of the VF also has higher magnification, by just the right amount to give the same sized VF image as with the old VF and 645 format. So the "D" VF image is likely to be about 1/2 stop dimmer with lenses of equal maximum f-stop, unless the screen brightness has been improved to compensate.
Where the "full frame" claim is still weak is that with other lenses, all the "HC" ones, the FOV is cropped, and so one needs to change to a new, shorter lens to get the same FOV as one got with 645 film format. Worse, in many cases the new FOV choices do not match up.
For example, the 80/2.8 HC "normal" lens for 645 format film now gives a narrower than normal FOV when used with "48mm format", while the next lens down, the 55/3.5 gives a wider than normal FOV (wider than 80mm in 645 format). And that 55/3.5 is slower and more expensive than the 80/2.8, as is typical when going from a normal to a wider FOV design.
To fully achieve the goal of a Full Frame 48mm format system, Hasseblad/Fuji ideally need a new array of HCD lenses, at least offering all the desirable wide to normal FOV choices. Maybe a 60mm HCD normal lens f/2.8 or faster should come soon, to match the 60mm diagonal size of 48mm format.
P.S. Pentax has recently made it clear that its plans are for its digital MF system to stay with 33x44mm format, rather than moving up to 36x48mm, let alone to 42x56mm (645). I see no other way to interpret the Pentax claim that its "645D" system will eventually get up to only about 30MP (matching the curent maximum pixel count of 33x44mm sensors), when 36x48mm already offers higher pixel counts than that.
Pentax have a new "normal lens" coming to that format: a 55mm to match the 55mm diagonal of 33x44mm. But is there a 28mm or 25mm wide angle lens coming?