Digital BW, The Print

Mark writes:

> Umm, we are mixing pixels with sensor elements here.  Sure, the
> typical CCD does not provide a true rgb pixel for every sensor
> element, it has to interpolate one from adjoining elements which
> means your effective pixel area is larger than any individual sensor
> element, but that doesn't mean that information is being "thrown
> away" ...

Yes, it does.  Since each photosite on the sensor receives only one primary
color, the information for the other two colors is being thrown away.
Overall, 2/3 of the total RGB image information is lost; software simulates
the lost information by interpolation, but simulation is not recovery.

> Sure, a true and instantaneous scan of each rgb channel
> would be preferable, but in real life there are so many
> variables in film scanning that the benefits are probably lost...

I can see the benefits pretty easily.  Colors bleed on digicam photos
because of the interpolation.  They do not on film scans.

> When you convert to gray scale you don't necessarily "lose"
> quality over your rgb information, you are just getting there
> in a terribly inefficient manner...

No, there is an actual loss, and it is quite significant, particularly with
digicam photos, since they've already sacrificed 2/3 of the RGB information.
Even in the case of color film, however, the RGB capture throws away most of
the image information in the original scene, and so almost all the
flexibility of true B&W capture is lost.

The only way to have the full flexbility and depth of information of black
and white is to capture in black and white to begin with.

> ... comparing scanners and digicams and making a blanket statement that
> you get 3 times the information from a scanner is really misleading
> at best.

No, it is 100% correct.  Film captures all three colors.  Individual dye
clouds are much smaller than scan pixels, so each pixel contains information
for all three primaries in a film scan.  In digicam photos, 2/3 of this
information is absent.

> Then why the heck would anyone shoot Technical Pan
> film then????

Technical Pan has even higher resolution and even less grain.  I said
"similar to," not "equal to."

Portra 400BW is a good compromise when Tech Pan is not practical or
possible.

> I can't even conceive how anyone can make this statement?

Neither can I.  If anyone ever actually makes that statement, you may want
to ask him about it.

The rest of your questions on this point and the many question marks that
follow them are moot, given the above.

> I don't think there is a real argument here anyway... just
> semantics...

There is a real loss of information in digital capture versus film capture,
even for equal numbers of pixels.  In addition, all conversions from RGB to
B&W involve an enormous loss of information compared to straight B&W
capture, and this is true whether the capture is digital or film (although
it is slightly worse with digital capture).

I still think we are splitting hairs and arguing semantics which 
isn't really valuable, but personally, I would prefer a 6MP CCD/CMOS 
image over a straight 6MP scan with grain aliasing and all... you 
apparently don't agree... no problem.

Also, for some reason you clipped your quote out of my reply, "Portra 
400BW gives results that are similar (if not equal to) Technical 
Pan..."  so I was "asking him [ie. you] about it" :)  I currently 
have been shooting two cameras, one loaded with TP and a second with 
either T400CN or Portra 400BW... felt your comment "similar (if not 
equal to)" meant that there wasn't any real reason to be doing so... 
I do... I also consider the two films *not* similar or equal...  
Portra 400BW is a great film though.

mark

...
> > Then why the heck would anyone shoot Technical Pan
> > film then????
> 
> Technical Pan has even higher resolution and even less grain.  I 
said
> "similar to," not "equal to."
> 
> Portra 400BW is a good compromise when Tech Pan is not practical or
> possible.
> 
> > I can't even conceive how anyone can make this statement?
> 
> Neither can I.  If anyone ever actually makes that statement, you 
may want
> to ask him about it.
...

Mark writes:

> I still think we are splitting hairs and arguing semantics which
> isn't really valuable, but personally, I would prefer a 6MP CCD/CMOS
> image over a straight 6MP scan with grain aliasing and all... you
> apparently don't agree... no problem.

We are all entitled to personal preferences, but it is important to
understand that RGB conversions to black and white are not the same as
shooting black and white to begin with.  This means that, in film, it's best
to shoot with black and white film if you want the full range of
possibilities for black and white.  It also means that, at present, the
black and white possibilities for digital capture are limited, since there
aren't any black and white digital cameras (if there were, however, they'd
offer possibilities similar to film).

Print black and white from color thus limits flexibility severely, but if
the B&W look that you want is obtainable from RGB conversion, then certainly
there is no reason to shoot with B&W capture.  If you like to use exotic
filters, narrowband filters, etc., when shooting black and white, then RGB
is likely to give odd results.  As an extreme example, you'll never get
infrared from RGB conversions.  Nor will narrowband yellow or other filters
produce the expected results.

> Also, for some reason you clipped your quote out of my reply, "Portra
> 400BW gives results that are similar (if not equal to) Technical
> Pan..."

I quoted it myself again, however.

Portra 400BW provides amazingly high resolution and fine grain, particularly
given its relatively high speed.  It also has great latitude, making it
useful for contrasty scenes (such as night scenes).  It is not the equal of
Technical Pan, which has a different look, still higher resolution, and
still finer grain.  But Portra 400BW is a lot closer to Tech Pan than it is
to Tri-X, and if you cannot shoot TP, Portra 400BW has many similar
qualities.  I can shoot night scenes handheld with Portra, for example,
whereas TP doesn't offer that option.

> ... felt your comment "similar (if not equal to)" meant
> that there wasn't any real reason to be doing so...

Oh no.  Technical Pan is a great film, and when it's possible to shoot it,
it is well worth shooting.  Portra 400BW is not an acceptable substitute
when you need the specific qualities of Technical Pan.  But if you cannot
shoot TP and you need something with very fine grain and very high
resolution, particularly at a much higher speed, Portra is handy.

That is true and why I was out playing with both a Canon 10D and 300D 
today trying to decide which one to buy for myself... and not out 
shopping for a better film scanner:)

mark

...
> We are all entitled to personal preferences...
...

Anthony,

Just a  quibble with your use of "thrown away". I don't think you can throw
away something that you have not captured. If you substitute "not captured"
for "thrown away" and "missing" for "lost", I would agree wholeheartedly
with you.

BUT, that doesn't explain why it is much easier in my experience to get good
18x12 prints from my D100, than from my F100 with Provia 100F scanned with
either a Nikon LS4000 or a Minolta 5400.

Bob Frost

----- Original Message ----- 
From: "Anthony Atkielski" <anthony@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>
> Yes, it does.  Since each photosite on the sensor receives only one
primary
> color, the information for the other two colors is being thrown away.
> Overall, 2/3 of the total RGB image information is lost; software
simulates
> the lost information by interpolation, but simulation is not recovery.