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Author Topic: what "full frame" means  (Read 2117 times)
BJL
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« on: October 02, 2006, 10:51:23 AM »
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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?
« Last Edit: October 02, 2006, 11:01:21 AM by BJL » Logged
free1000
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« Reply #1 on: October 04, 2006, 01:18:43 PM »
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This is sophistry on the part of Hassleblad.

You are right in saying that 'full frame' could be given this new interpretation, however it is not how the term is generally understood by the customer base.

Often in such circumstances marketers invent a new term to describe the new interpretation, however in this instance Hasslecon chose to repurpose a word that was already well understood.

Don't believe that the closed loop approach can only be achieved at the expense of openness either, thats another con.  Its certainly a lot simpler for Hassleblad to close the loop, but not impossible for the other back vendors and camera manufacturers to agree a new standard for integration which allows similar benefits but without the closed ness of the Hassleblad approach.

If however, only one or two MF manufacturers eventually survive then I suspect that both systems will end up closed. Hopefully they will still support the use of their backs on view cameras in some kind of compatibility mode.

Another interesting aspect of this is that Hassleblad are pretty much admitting that lens design is as good as it can be in terms of price performance. I never really liked the results of post processing my 1DsII files to pretend they were better than they were. What I liked about the shift to MF was the way files were just better, without software fixes.

If lenses really can't be improved optically, I suspect that we are near the end of the technology curve with conventional optics. Resorting to software fixes is only necessary if you can't do the job properly.
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Graham Mitchell
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« Reply #2 on: October 04, 2006, 03:13:25 PM »
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The H series is a 645 platform. Hasselblad have stated that many times. So to call any camera 'full frame' when there is still a crop factor involved is disingenuous at best. If the H3D also takes 645 film backs then this just becomes messy and confusing. marketing departments should be subject to more censorship.
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BJL
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« Reply #3 on: October 04, 2006, 03:39:53 PM »
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I agree with one major criticism of this "full frame" claim, which is that many of the lenses are optimized for 645 format and so users are still likely to suffer from an enforced crop in many situations.

However, I reject the idea that a full frame system must of necessity _not_ accept lenses designed for a larger format, or that it must _not_ also offer the option of using a larger format with a suitable back. That would be to declare that _adding_ an ability is somehow a disadvantage, and that only cameras lacking such flexibility have the superior status of being "full frame".

No-one says that Pentax 35mm format SLR's are not "full frame" simply because Pentax offers adaptors allowing one to use Pentax medium format lenses on those bodies. And what of the Mamiya 6x7 format cameras that also accepted 6x8 film backs?

As far as I can see, a system avoids the criticism of imposing an "enforced crop" when it offers a satisfactory collection of lenses, viewfinders, light metering, auto-focus etc. free from any cropping problems. The exisence of another similar but larger format, or the ability to use lenses dsigned for that larger format, should not enter into it.

Hasselblad has a long to go to achieve this; or rather its lens supplier Fujfilm has a long way to go with the HCD lens series, since Hassleblad/Fuji have dealt with the other issues (VF, metering, AF are all apparently adapted to the 36x48mm frame by the new viewfinder).

If one day there is a Fujinon HCD lens offering about the same angular FOV in "48mm format" as each current HC lens offers in 645 format, the system will be "Fully Full Frame 48mm" to me.


P. S. How do you define "full-frame", in a way that it is an advantage over the "non-full-frame" alternative?
I do not know of an agreed, established definition, and I have already rejected "the same as a common film camera format".
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