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Thread: Who needs more than 40mp on a MFDB?

  1. #51
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    Re: Who needs more than 40mp on a MFDB?

    Quote Originally Posted by GrahamWelland View Post
    Now if there was an IQ145+ then I think that many people would be in digital back heaven. Well, certainly anyone who wants or needs to shoot for longer than a couple minutes or so. The P45+ in an IQ or Credo form factor with the enhanced UI really would hit the spot.
    When I was looking at the IQ's at first release I too thought the same and even expressed my interest to Phase One. However, I think that 39MPix Kodak chip is no longer manufactured so that quashes all chances of over 2 minute long exposures ever happening this side of a CMOS chipped Phase One back.

  2. #52
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    Re: Who needs more than 40mp on a MFDB?

    Quote Originally Posted by gazwas View Post
    When I was looking at the IQ's at first release I too thought the same and even expressed my interest to Phase One. However, I think that 39MPix Kodak chip is no longer manufactured so that quashes all chances of over 2 minute long exposures ever happening this side of a CMOS chipped Phase One back.
    There's still the KAF-50100, the 6um 50 megapixel variant used by Hasselblad for example. From the data sheets most look the same as the KAF-39000 except smaller pixel size. There's no micro-lenses, the color cast seems as good/bad as the P45+. The requirement of wakeup procedure does not feel that modern though...

    The Dalsa FTF-6080C 48 megapixel 6 um is also interesting I think, only(?) used in the tethered-only Sinar eXact. No long exposures possible with that though.

    Both sensors are "old" technology though, would be nice to see some new development in the 6um pixel size in the future.

  3. #53
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    Re: Who needs more than 40mp on a MFDB?

    I can never understand the point of comparing "shiftability" of the same lens on different sized backs. Assuming same sized pixels (as is the case between the IQ160 and IQ140) you gain absolutely nothing by choosing the crop back.

  4. #54
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    Re: Who needs more than 40mp on a MFDB?

    Quote Originally Posted by torger View Post
    ...and P45+ *is* ideal!

    Some shift stats of landscape orientation:
    70mm (Rodenstock Digaron-S)
    54x40: 2.3mm/5.8% rise/fall, 1.8mm/3.3% shift left/right
    48x36: 7.5mm/21% rise/fall, 6mm/12.5% shift left/right
    44x33: 10.7mm/32% rise/fall, 8.9/20% shift left/right
    The 70mm Digaron-W, which I use on the Max, can pretty much shift to the max of the Max on the IQ180 (shift +/- 18mm, rise/fall 25/18mm). It has a 100mm image circle.

    90mm (Schneider Digitar, Rodenstock Digaron-W)
    54x40: 16.0/40%, 13.3/25%
    48x36: 20.0/55%, 17.2/36%
    44x33: 22.7/68%, 19.8/45%
    And that has a 125mm image circle, so if I can shift the 70HR 18mm, I rather suspect I'll be able to shift the 90 rather more than you mention there.

    /edit

    FWIW, here's the 70HR on the IQ180. 9-shot stitch (in portrait) to the full limits of the ALPA Max:



    Full size is 280MP.

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    Re: Who needs more than 40mp on a MFDB?

    Quote Originally Posted by gerald.d View Post
    I can never understand the point of comparing "shiftability" of the same lens on different sized backs. Assuming same sized pixels (as is the case between the IQ160 and IQ140) you gain absolutely nothing by choosing the crop back.
    It's about economy.

    We could have a chip say 90x90mm so we cover the whole image circle all the time and just crop in post, and then we could skip having movements on the camera at all. However a large chip is exponentially more expensive than a small chip, so with smaller chips you can make cheaper backs. Thus I think it is a good idea to not make sensors larger than they need to be.

    I also find it more enjoyable to compose with the tech cam, shift the sensor into the right position, rather than cropping in post although the result is exactly the same of course.

    Likewise, I think it is a good idea to provide lenses that don't resolve more than they need to do, as you can use simpler more cost effective lens designs.

  6. #56
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    Re: Who needs more than 40mp on a MFDB?

    Quote Originally Posted by gerald.d View Post
    125mm image circle
    Yes, image circles of longer focal lengths are generally larger -- it is unavoidable from the lens design. The 70/90mm IC limit is more clear in the wide end. Wide angles is the difficult part. Hard to make large image circles, hard to make sharp to the corner, hard due to vignetting and color cast issues.

    I was not really clear either I realize now. What I meant with 70/90 is the image circle diameter, not the focal length. The Digaron-S wides has 70mm image circle, the Digaron-W wides has 90mm image circle.

  7. #57
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    Re: Who needs more than 40mp on a MFDB?

    Quote Originally Posted by torger View Post
    Yes, image circles of longer focal lengths are generally larger -- it is unavoidable from the lens design. The 70/90mm IC limit is more clear in the wide end. Wide angles is the difficult part. Hard to make large image circles, hard to make sharp to the corner, hard due to vignetting and color cast issues.
    Ahh. Apologies - you were talking about 70mm and 90mm image circles, I thought you were talking about 70mm and 90mm focal lengths.

  8. #58
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    Re: Who needs more than 40mp on a MFDB?

    Quote Originally Posted by gerald.d View Post
    Ahh. Apologies - you were talking about 70mm and 90mm image circles, I thought you were talking about 70mm and 90mm focal lengths.
    It's my fault, I was not clear in the original post, updated it now.

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