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Author Topic: Canon's lack of a roadmap  (Read 8835 times)
BartvanderWolf
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« Reply #40 on: December 06, 2013, 03:48:43 AM »
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Since I was talking about the attitude of traditional film users to this idea of "too much resolution if not all lenses can make use of it", it is a little strange bringing scanning into the story;

Hi,

Many people do not fathom that the resolution or acutance film/sensor alone, doesn't mean much in isolation. A film alone doesn't a picture make... What's more, many people still think that the worse element of the imaging chain sets the limit (as some may interpret the subject line you changed from the OP's), while the limit will actually be worse than the worst component, because the MTFs multiply. It therefore helps most to improve the worst element of a chain, as it does in a real chain.

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I would think that most of those B&W film users were printing in the darkroom rather than scanning!

Maybe, maybe not. Anyway, it seems harder every day to produce silver-based output, and easier to produce inkjet output. Also posting on the web or archiving digital copies off-site will require scanning the material, and it gets harder to find a competent scanner operator (and even scanners). So it is a development that will add another MTF to the imaging chain.

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And why do you bring color films into the discussion when I was specifically talking about fine-grained B&W films?

Because there are only a few true monochrome digital cameras / backs around, and most people base their judgment on a Bayer CFA equipped sensor array, and that will lower the MTF50 metric. Besides, post-processing an image that is color from the start will allow much better control over B/W tonality than with a simple lens filter, so one can produce creatively superior results.

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I do not dispute that recent 35mm format sensors out-resolve color film.

But thank you for reminding me of Technical Pan: by the measures in that Kodak document and the one above, there is not much between them, but TMAX100 has somewhat higher MTF across most of the frequency range.

Yes, but with very low granularity (=5) for the Technical Pan, versus the T-MAX 100 (=18), thus allowing huge output with little grain showing.

Cheers,
Bart
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BJL
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« Reply #41 on: December 06, 2013, 09:37:05 AM »
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I agree that the degradation in printing needs to be taken into account --- but isn't that just part of the argument that it can be worth using a sensor/film offering more resolution/detail than the limits set by other parts of the processing chain or "signal path"? My economic rule of thumb is that one should identify the component where improving performance [MTF?] is cheapest and push it somewhat past the performance of the rest of the system, and increasing pixel count in a sensor of the same size is not that expensive.

I was explicitly talking about photographers finding it worthwhile to use films like TMAX100 and Tech Pan back in the days of darkroom printing, before scanning, not what people are doing with film these days.

TMAX100 had granularity of 8, not 18, but I agree that Tech Pan is better [5] on that measure; my conclusion is that the two are roughly comparable overall, desire advantages to each is various respects.

The fact that most sensors use Bayer CFAs, and therefore sacrifice some resolution to CFA and demosaicing, just strengthens my point: to compare the "sensor resolution" that many B&W film users found worthwhile to the sensor resolution currently offered by things like the 7,360 x 4,912 pixels (36MP) of the D800E. Demosaicing goes in the balance on one side just as scanning or the effects of printing with an enlarger go on the other side.
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Colorado David
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« Reply #42 on: December 06, 2013, 10:41:41 AM »
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It therefore helps most to improve the worst element of a chain, as it does in a real chain.

This is almost verbatim from The Theory of Constraints.  You maximize your improvement by throwing all of your resources at improving the weakest link.  Spreading your resources over the entire process actually minimizes the potential for improvement because only the improvement to the constraint improves the end result.  After you improve the constraint, then you re-evaluate, identify the new constraint and throw all your resources at it.
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BartvanderWolf
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« Reply #43 on: December 06, 2013, 11:36:14 AM »
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TMAX100 had granularity of 8, not 18, but I agree that Tech Pan is better [5] on that measure; my conclusion is that the two are roughly comparable overall, desire advantages to each is various respects.

You're right, I overlooked the figure [8] at halfway the document.

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The fact that most sensors use Bayer CFAs, and therefore sacrifice some resolution to CFA and demosaicing, just strengthens my point: ...

Sorry, I disagree (explained below).

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... to compare the "sensor resolution" that many B&W film users found worthwhile to the sensor resolution currently offered by things like the 7,360 x 4,912 pixels (36MP) of the D800E.

And that exactly illustrates why I disagreed above. The 35mm film scan @5400PPI gives 7654x5102 pixels and the D800/D800E gives 7360x4912 pixels. However, one cannot compare the 'sensor' resolution in isolation. One delivers a partial product that will degrade further upon scan/print, and the other is already output 'ready' and will not degrade at all.

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Demosaicing goes in the balance on one side just as scanning or the effects of printing with an enlarger go on the other side.

The degradation is very much incomparable in magnitude.

This is almost verbatim from The Theory of Constraints.  You maximize your improvement by throwing all of your resources at improving the weakest link.

Absolutely correct, it always helps to improve the weakest link. However, in the case of cascading MTF responses, a combination of 50% and 40% response at e.g. MTF50 gives a combined MTF of 0.5 x 0.4 = 20% . Improving the worst of the two (40%) to 50% will boost the combination to 0.5 x 0.5 =25% MTF, and boosting the best (50%) to e.g. 62.5% gives 0.625 x 0.4 = 25%, IOW the same result.

So in the case of cascading MTFs it can also pay to improve the second weakest link instead (although it may be cheaper to improve the weakest, or not).

Cheers,
Bart
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BJL
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« Reply #44 on: December 06, 2013, 02:56:30 PM »
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I would rather discuss what I actually said (and later clarified), not a misinterpretation of it.  So to repeat, I was referring to the fact that some years ago, when 35mm format B&W negatives were printed directly with an enlarger, not via scanning, many photographers found it worthwhile using very fine grained high resolution monochrome films like Kodak TMAX100 and Tech Pan or Ilford PAN F Plus or Delta 100. So I am not so interested in discussions of scanning at 54ppi, or color films.

I admit that I totally do not understand some of your latest comments: sensors with Bayer CFAs can only give lower MTF at a given spatial frequency] than monochrome sensors or ideal scans at the ppi, and this can only increase the pixel density needed before the resolution/detail/MTF performance reaches the level of being "excessive" relative to the rest of the MTF chain.

But at least we agree on this about dealing with "multiplicative" combination of defects:
... in the case of cascading MTFs it can also pay to improve the second weakest link instead (although it may be cheaper to improve the weakest, or not).
Or to put it another way, it can be worth improving the second weakest link to be significantly better than the weakest link if this second weakest link is cheaper to improve. Which I suspect is the case with increasing sensor resolution (at equal sensor size) versus improving lenses.
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