Medium format versus digital sharpness

Scott W wrote:

> If you re-read what David wrote you will see that he said to make the
> print with you favorite method, no throwing away quality there,

'Yes'...
Print sizes have nothing to do with how good a MF scan is compared to a
direct digitalo capture file.
Comparing both using a fixed, small print size is an even worse thing to do.
You don't see that (it's simple though), so i'll explain:

You can produce perfectly good passport photo format prints using a 2MP
camera.
You can do that too using an 8x10" film camera.
You can then calculate that you would need to scan that 8x10" using a
certain resolution to get a good result print of that size.
You can then also mention that the print you make from the 2 MP camera looks
equally good (an assertion - why not calculate that too?) at that size.
And hey presto: there it is: 2 MP is just as good as 8x10".

> [...]
> In the end if you can't produce a good looking print, then what is the
> point?

Do you now see the point?

I'll tell you again, just to be sure: when you want to compare scanned MF to
direct digital capture, this is the silliest way of trying to do so.
I'll explain why again too: you are not comparing scanned MF to direct
digital capture at all. Just playing foolish games.
 >> Stay informed about: Medium format versus digital sharpness 

Scott W wrote:

>> Quite impressive, or disturbing rather, is that you find that impressive.
>> Why is that?
>>
>>
>
> Because an 112MP image that is not all soft and full of noise if pretty
> dam impressive.

But was that (you being impressed) the subject? If you read again, you'll
find it's not.

> I have to wonder if you have ever seen one, [...]



Now i'm sure - as if i wasn't when you said that an 11 MP image is "dam
impressive" - that you have never seen what a really good image file looks
like.
Scott, you asked me before if i had (seen) an 112 (!) MP file. I told you i
have.
 >> Stay informed about: Medium format versus digital sharpness 

Matthew Winn wrote:

> That's 102 line pairs per millimetre, which is at least double what
> I'd expect for average consumer film because the ability to retain
> contrast down to the level of individual grains is poor. [...]

Shows how much nonsense is passed around in these digital vs film
discussions.
I'm sorry i got involved in one - i know i shouldn't and normally i don't.
Serves me right...

Quite normal, 'average' films, like Kodak's T-Max or Portra, the staple of
many photographers, resolve well beyond 102 lp/mm.
And laying that much down on film is not a tall order for even quite
'average' lenses either.

But that doesn't suit the how-good-digital-capture-is camp at all.
So they forget about the soft focus filters that are in front of their
sensors. they forget about the small size of their sensors, and still think
that because the file that comes out at the end contains so many pixels, it
must be very good.

And converseley, a 'sensor' that has a much higher resolution, is larger and
thus has more area to capture even more detail to boot, can not be as good,
because it isn't 'digital' to begin with.
Or rather would make these expensive dslrs look bad, and we can't have that,
can we? So we won't.

Dear, oh dear, oh dear...
 >> Stay informed about: Medium format versus digital sharpness 

On Sun, 7 Oct 2007 20:49:32 +0200, "Q.G. de Bakker" <qnu.DeleteThis@tiscali.nl>
wrote:

>Quite normal, 'average' films, like Kodak's T-Max or Portra, the staple of
>many photographers, resolve well beyond 102 lp/mm.
>And laying that much down on film is not a tall order for even quite
>'average' lenses either.

In which case the resolution of the system would be around 74 lp/mm.
Moreover, only the slowest traditional black and white films approach
that 102 lp/mm number. Portra 160NC is generally rated around 75 lp/mm.
Source:

http://aic.stanford.edu/sg/emg/library/pdf/vitale/2007-04-vitale-filmg...n_resol

Finally, if you are trying to determine megapixels, with film that
implies scanning, with the inherent sampling losses of that technology.
If you don't scan and try to compare print quality, you have to try to
figure out how to equalize the analog vs. digital print processes.

Don't get me wrong. I'm not claiming that even the best 24x36mm dSLR
can match a 6x7 film camera. But trying to reduce the difference down
to a number of megapixels is not a simple exercise, nor to my mind is it
a useful exercise.

--
Michael Benveniste -- mhb-offer.DeleteThis@clearether.com
Spam and UCE professionally evaluated for $419. Use this email
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 >> Stay informed about: Medium format versus digital sharpness 

"Q.G. de Bakker" <qnu.RemoveThis@tiscali.nl> wrote:
>
> There is loads more usefull detail in scanned MF than there is in the
> (relatively) small direct capture files.

Sure. There's between 1.5 and 2 times as much useful detail in a high-res
scan of a 6x7 frame as there is in a 12.7MP 5D image. Mamiya 7, TMX100, 65mm
lens vs. 5D with Tamron zoom. The 6x7 scan handles the high contrast detail
in archtecture and signs noticeably better than the 5D. But when the
contrast is lower, there's no advantage. And the slide films people actually
use aren't as good as TMX100.

The idea that a single frame of 6x7 film has almost ten times (112/12.7) as
much information as a single 5D frame is completely ridiculous: you are off
by a factor of four.

Everyone who has tried to do the comparison with any amount of seriousness
comes to basically the same conclusion (i.e. 35mm = 6 to 8MP, 645 = 12 to 16
MP, 6x7 = 24MP). Except QG.

David J. Littleboy
Tokyo, Japan
 >> Stay informed about: Medium format versus digital sharpness 

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 >> Stay informed about: Medium format versus digital sharpness 

On Sun, 7 Oct 2007 20:49:32 +0200, "Q.G. de Bakker" <qnu RemoveThis @tiscali.nl>
wrote:

> Matthew Winn wrote:
>
> > That's 102 line pairs per millimetre, which is at least double what
> > I'd expect for average consumer film because the ability to retain
> > contrast down to the level of individual grains is poor. [...]
>
> Shows how much nonsense is passed around in these digital vs film
> discussions.
> I'm sorry i got involved in one - i know i shouldn't and normally i don't.
> Serves me right...
>
> Quite normal, 'average' films, like Kodak's T-Max or Portra, the staple of
> many photographers, resolve well beyond 102 lp/mm.

I don't consider Portra an "average consumer film". Not many average
consumers keep their film refrigerated.

It depends what you mean by "resolve". Kodak's own MTF graph for
Portra 160NC-2 cuts off at about 80 lp/mm, at which point it's at 50%
for the blue-sensitive layer and 25% for red. Extrapolating, at 100
lp/mm the best the film can manage is about 35% in the blue-sensitive
layer. 160VC-2 is a little better, managing around 40% at 100 lp/mm
for blue although the red is down at 15%. This is what I meant by
the gradual roll-off of resolution meaning that an exact figure is
meaningless. If you're photographing a subject with low contrast,
then once you've taken the lens into account the detail that might
be retained by the film at 100 lp/mm is getting lost in the noise.

I've standardised on 160VC-2 -- I think it's the best colour negative
film Kodak have produced since Vericolor III S -- but it's clear that
the image is getting mushy at 80 lp/mm even with the best prime lenses
I have.

> And laying that much down on film is not a tall order for even quite
> 'average' lenses either.
>
> But that doesn't suit the how-good-digital-capture-is camp at all.
> So they forget about the soft focus filters that are in front of their
> sensors. they forget about the small size of their sensors, and still think
> that because the file that comes out at the end contains so many pixels, it
> must be very good.

I am wondering how much the theoretical performance of the latest high
resolution sensors is compromised by the capabilities of the lens.

--
Matthew Winn
[If replying by mail remove the "r" from "urk"]
 >> Stay informed about: Medium format versus digital sharpness 

Q.G. de Bakker wrote:

>> In the end if you can't produce a good looking print, then what is the
>> point?
>
> Do you now see the point?
>
> I'll tell you again, just to be sure: when you want to compare scanned MF to
> direct digital capture, this is the silliest way of trying to do so.
> I'll explain why again too: you are not comparing scanned MF to direct
> digital capture at all. Just playing foolish games.

I believe you misunderstood Scott's suggestion.

He suggested comparing a film-capture to a sensor-capture based on
print quality - which is a perfectly reasonable thing to do. A capture
that is never printed, projected or viewed on a screen might as well
not exist.

Scott suggested finding the limits of enlargement as a way
to compare scanned film to a sensor-capture, which has nothing
to do with passport photos.

Dana
 >> Stay informed about: Medium format versus digital sharpness 

Michael Benveniste wrote:

> In which case the resolution of the system would be around 74 lp/mm.

No, no. That is the resolution as found on exposed film.
None of that "system resolution" malarky.


> Moreover, only the slowest traditional black and white films approach
> that 102 lp/mm number. Portra 160NC is generally rated around 75 lp/mm.
> Source:

Portra is not 'rated', but seen recording 140 lp/mm.
http://www.zeiss.com/C12567A8003B58B9/allBySubject/6F2949A15BD8DB74C12...EF002B0

> Finally, if you are trying to determine megapixels, with film that
> implies scanning, with the inherent sampling losses of that technology.

That depends on the scanner.
You can't just assume that the thing performs that bad that you lose
resolution.

> If you don't scan and try to compare print quality, you have to try to
> figure out how to equalize the analog vs. digital print processes.

And that "prints" red herring again...
The question was how many MP there are in film. Not how you many of them you
can save or can squander while laying them down on paper.

> Don't get me wrong. I'm not claiming that even the best 24x36mm dSLR
> can match a 6x7 film camera. But trying to reduce the difference down
> to a number of megapixels is not a simple exercise, nor to my mind is it
> a useful exercise.

I agree.
I shouldn't have responded at all.
It's just sad to see entire new generations being brought up to believe the
greatest nonsense, unchallenged...
 >> Stay informed about: Medium format versus digital sharpness 

"Q.G. de Bakker" <qnu.TakeThisOut@tiscali.nl> wrote:

>> Moreover, only the slowest traditional black and white films approach
>> that 102 lp/mm number. Portra 160NC is generally rated around 75 lp/mm.
>> Source:
>
> Portra is not 'rated', but seen recording 140 lp/mm.
> http://www.zeiss.com/C12567A8003B58B9/allBySubject/6F2949A15BD8DB74C12...EF002B0

Zeiss typically assumes a contrast differential of 2-5% for its
measurements,
which is meaningless for photographic purposes. This is the main reason
why
Zeiss lp/mm numbers are so high for its lenses. The study I cite used a
more
reasonable 30% criterion.

> That depends on the scanner.
> You can't just assume that the thing performs that bad that you lose
> resolution.

I can assume the Nyquist-Shannon sampling theorem applies. So in order
to not lose resolution, your scanner needs to sample at twice the
resolution of the original image. So to get 75 lp/mm you would need to
scan at over 7500 dpi. And that assume a perfect optical system in the
scanner and perfect film flatness. It also assumes that the data and
sampling are "in phase."

As a demonstration of scanning loss even with an 8000 dpi drum scanner,
I suggest you look at the following article:
http://www.normankoren.com/Tutorials/Scan8000.html

--
Michael Benveniste -- mhb-offer.TakeThisOut@clearether.com
Spam and UCE professionally evaluated for $250. Use this email
address only to submit mail for evaluation.
 >> Stay informed about: Medium format versus digital sharpness 

Recently, Michael Benveniste <mhb-offer.RemoveThis@clearether.com> posted:
>
> As a demonstration of scanning loss even with an 8000 dpi drum
> scanner, I suggest you look at the following article:
> http://www.normankoren.com/Tutorials/Scan8000.html
>
It appears that this person is attempting to justify his purchase and use
of a Canoscan FS4000US rather than provide a useful comparison between
scanning technologies. I don't understand why folks think that Imacon
produces a "high-end drum scanner", AFACT, they do not.

http://www.hasselbladusa.com/products/scanners/flextight-x5.aspx

The Imacon line is CCD-based, and one can expect that the qualities and
limitations of that technology would not be drastically different due
solely to an increase in the number of sampling sites. To suggest that
this is as good as it gets ignores a lot of available PMT-based technology
in truly "high-end drum scanners".

All that said, I agree with your premise that the question is not simple,
and perhaps it is not even a meaningful one to compare MF film and digital
capture. They are completely different with unique advantages and
disadvantages.

Regards,

Neil
 >> Stay informed about: Medium format versus digital sharpness 

Matthew Winn wrote:

>> Quite normal, 'average' films, like Kodak's T-Max or Portra, the staple
>> of
>> many photographers, resolve well beyond 102 lp/mm.
>
> I don't consider Portra an "average consumer film". Not many average
> consumers keep their film refrigerated.

The one has nothing to do with the other.
First, resolution does not depend on colour balance. You do not need to
refrigerate film to keep the three B&W layers capable of resolving what they
do.

Second: yes, Portra is a run-of-the-mill film. Like i said: teh staple of
many photographers.

And there's a "third" too:
Why are you looking for "consumer" grade film to compare digital to?

> It depends what you mean by "resolve". Kodak's own MTF graph for
> Portra 160NC-2 cuts off at about 80 lp/mm,

Yep. That's the graph.

> at which point it's at 50%
> for the blue-sensitive layer and 25% for red. Extrapolating, at 100
> lp/mm the best the film can manage is about 35% in the blue-sensitive
> layer.

"Extrapolating"...
Let's suppose 35%. That means the detail is there in a quite visible, and
retrievable way.
Not that it is not there.

> 160VC-2 is a little better, managing around 40% at 100 lp/mm
> for blue although the red is down at 15%. > [...]
> -- but it's clear that
> the image is getting mushy at 80 lp/mm even with the best prime lenses
> I have.

And that's the the big difference between film and digital. Though the
detail starts to "get mushy", it is still recorded on film.
Digital sensors do not do that at all: it's either there, or not at all.

> I am wondering how much the theoretical performance of the latest high
> resolution sensors is compromised by the capabilities of the lens.

Not at all.
The soft focus filter typically cuts-off at 50 lp/mm.
Only very bad lenses do not go beyond that.
 >> Stay informed about: Medium format versus digital sharpness 

David J. Littleboy wrote:

> That's plenty to create significantly better looking images than 35mm film
> can even dream of. If you take your eye off the test charts under your
> microscope and actually look at some prints. (Cheapshot a QG, not you.)



David, that microscope is a scanner.
The result is a file with very usefull information. Information your digital
sensor just does not capture.

By the way: you have noticed the title of this thread, have you?
Why is it that digi-guerrileros like you keep dumbing down the competition
in your efforts to proof that your favourite is at least as good...?

 >> Stay informed about: Medium format versus digital sharpness