Moose-Schnozz wrote:
> Omigawd! We're blood brothers after all. Forget all the nasty
> things I've said. :-)
Twins, seperated at birth.
> I don't believe stock requirements will just keep going up.
> Above a certain point, there just aren't uses for which the
> extra resolution is needed. And the storage space required
> just shoots up.
Exactly. In fact we're actually starting to see the dumbing
down of the requirements a bit in Alamy's accepting of JPEGs
instead of TIFFs.
> There was a drop in requirements for the other advantages of
> digital, and now it will go back to about where it was. 4000
> dpi scans of 35 mm film are about 21 mp. And at 16 bit depth
> are about 120 mb. I don't think they capture as much detail
> as 12 mp images from the 5D, although part of that is the
> grain.
I doubt we'll see 16-bit file requirements because of the space
situation and the limited gain in usabiity.
As to the MP of film vs digital I'd like to relate a little
analog/digital comparision of another medium--sound:
When digital audio was getting its start, the "scientists" and
"engineers" took a good hard look at what the typical frequency
response of the human ear is and determined that they could
limit the recording medium to that point. After all, if you
can't hear beyond 20kHz, why bother recording beyond 20kHz?
This was very true for straight tones. It was also true for
*most* studio recordings of pop and country music. Classical was
another story, but it took more than a few years before the
reason why Classical didn't sound right was understood. It
really is true that vinyl "sounds better".
During the A-D process, the analog waveform is forced forward
and backward to fit into the nearest sampling bucket. This does
two things: It introduces a phase-shift and it also takes the
sound and moves it in the time-domain. If you sit blindfolded
in a room with a string-quartet playing you are able to
distinguish the exact placement of each of the instruments in
relationship to your seating location. Now, stick good quality,
non-time-smearing pair of mikes in a nice 6-inch spread and
record it directly to a high-speed analog-tape system and during
playback you will be able to still differentiate the same
placement of the instruments. If, however, you record this to
44,100 (at any bit-depth), you will lose some of that positional
accuracy and the seperation between instruments begins to blur.
What is going on here, is that the ear is unable to "hear"
beyond 20kHz, but it is able to detect the ARRIVAL of the sound
to a granularity of in excess of 120kHz. A high-quality A-A-A
vinyl recording (or master disk) will top out at about 15kHz of
true frequency response, but the position of the waveform is
precise whereas in digitial, the waveform has been time-shifted.
(by the way, the 120kHz sound sensing mechanism is a vital part
of the human survival--being able to detect where sounds come
from)
BTW, Why only 15kHz? That's all the physical medium can
support. However, that's not the end of the story. During
playback, the grooves move a needle connected to a transducer.
This mechanical playback is effectively a "first-time" creation
of the sound. You are not just playing back a recording, but
actually CREATING the sound complete with overtones. The
turntable actually is a musical instrument! These overtones can
easily be in excess of four octaves. Yup. 120kHz. This is why
an album can have a sense of "air" to it that digital doesn't.
Now, what does this have to do with digital imaging? The
greater the resolution (sampling rate) of the sensor, the
greater the resolution, the more likely the details of the scene
are kept in their real place. This *MIGHT* be one reason why
film pictures retain a sense of dimensional-depth to them which
digital images have been short of. You hear the complaint about
how "flat" digital images are, or the comments about "the
fishtank look".
When comparing raw resolution, digital images--even from my E-1
can match or exceed a 35mm scan. However, a 4000 DPI scan will
show positional accuracy missing in the digital images.
The 5D is, I believe, a turning-point camera in all this
discussion, though. Not only does the resolution pretty-well
match the best of 35mm film (and the lenses), but with the
nearly non-existant AA filter, it is able to maintain
positional-accuracy almost as well as film.
Yet, when compared to the really high-end scanning backs and
megapixel medium-format cameras, the 5D is still obviously
lacking something--the intangible.
AG
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