LF+scan+print: Case study, with prints

In article ,
"rafe b" wrote:

"G- Blank" wrote in message
...

Since the Nikon 90 is a very sharp lens I would anticipate that.
1/4 of a second though could be the reason and f 8 is not a VG
choice for depth of field (on a view camera). Is that your typical?

The more I have worked with bigger cameras the less concerned I am with
stopping all motion. Try this next time stop down to 22-32
and the surprise will be the large amount of what is in focus.


I'm sure the aperture was something considerably smaller
than f/8 -- that's just the lens rating (max aperture) I was
quoting. Most likely f/16 or f/22, but I really dunno.

In landscape work its a good practice use at least f/22 just my humble
opinion.

I don't record shutter/aperture for each shot, it's just
not my habit. (Not passing judgement on those who
do or don't, so no flames, please.)

Look, we can't control for technique, that's crazy.

No its not, why else shoot LF? Technique after all
for LF does have a big critical factor of film plane adjustment
however to make a perfect test original its best if the film and
lens planes are perpendicular and not skue'd.
Typical to what I might is shoot a scene that does not include too
much nearby stuff. I would chose maybe a wall or a building so I
can keep the standards fairly neutral.


Cherry-pick the sharpest sections of your sharpest
transparencies. I'm only interested in "best practice."
Don't even consider anything else.

I can use a different transparency or chrome also.
That one was chosen because it's the same image
I posted on the web. Lots of others to choose from.


rafe b
www.terrapinphoto.com



--
"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

greg_____photo(dot)com

On Fri, 20 Jan 2006 21:39:52 -0500, G- Blank
wrote:

In article ,
"rafe b" wrote:

Look, we can't control for technique, that's crazy.

No its not, why else shoot LF? Technique after all
for LF does have a big critical factor of film plane adjustment
however to make a perfect test original its best if the film and
lens planes are perpendicular and not skue'd.
Typical to what I might is shoot a scene that does not include too
much nearby stuff. I would chose maybe a wall or a building so I
can keep the standards fairly neutral.


Sigh. Do what you want, Gregory. You and I seem
to be the only folks here with even the slightest interest
in the original topic, and yet even between the two
of us we can't agree on a methodology.

This isn't an experiment to prove Scheimpflug.
It's been done. It's over. It's irrelevant to what
I'm trying to achieve with this comparison.

You needn't convince or educate me on the
technical benefits of LF as compared to other
cameras and film formats. I take it as a given.
That's why I'm on this NG, okay?

Surely in your collection you have prints from
LF chromes or negatives that you feel are
sharp and representative of your best technical
efforts. So use one of those.

Why make it difficult? It's not rocket science.


rafe b
www.terrapinphoto.com

Scott W wrote:

Tom Phillips wrote:
Scott the engineer...
Yup I am, and a highly paid engineer at that

This must explain your deep understanding of
imaging physics?

Fact: it take 4 pixels to make one real color
pixel using bayer pattern capture. Moasic
captures do not capture full color. They capture
one red, one blue, and two green pixels and then
interpolate. That's 8/4 = 2 mp

You guys are so utterly ignorant and unread.
24 million pixels is what photoscientists have
determined is the equivalant resolution for
400 speed 35mm color negative film.

So if we are to believe all that you say

See cite below.

you should be able crop 1/4
the area of a 35mm
frame of ISO 400 print film and get 6 real MP that will look just as
good as a 24 MP digital photo from a Bayer pattern camera.

You claim to be the "engineer," why don't you try it.
Just whip up a 24 MP one shot digital and I'll be
suitably impressed...

I would love to see that scan of ISO 400 print film.
In fact I would love to see your scan of ISO 400 print film that you
think comes close to the 1DS Mark II.

Scanned comparisions are bogus. You need to compare
a real enlargment with interpolated digital. As I said
earlier, you're not listening to what I'm saying: Enlargement
quality all depends on the optics and MTF. The scanning
[comparison] option ignores that any time you scan an image
you will either lose some detail or shift the Dmin/Dmax.

Do you have any idea at all how crazy you are sounding in all of this?

From "Progress and future prospects of silver halide photography
compared with digital imaging." Journal of Imaging Science and
Technology, vol 42, no. 1, 1998:

"The pixel size of a highly sensitive emulsion layer is assumed
to be 100 square micrometers on the basis of the fact that a
color film with an ISO 400 sensitivity and 135 format contains
24 million pixels....For a CCD the number of photoelectrons in
a pixel...is plotted as the number of absorbed photons per pixel.
For [a film] emulsion layer, the fraction of developable grains
is plotted as a function of the number of absorbed photons in
an area equivalent to a film pixel. In an evaluation of image
quality of [4x6 consumer prints] taken with ISO 400 color
negative film vs.CCD digital camera, the film image quality was
on par with that of a CCD with 6 million pixles."

Thus as I stated earlier 6 mp is all that's needed for comparable
digital image quality in typical prints. However, since you claim
to be an engineer (obviosly not an imaging engineer...) you should
have also taken note of my qualification that imaging resolution
is directly related to MTF. Thus in enlargement, optics, the film
resolving ability, and MTF combine to produce optical image
quality. Digital falls short here, since it simply cannot handle
the higher signal frequencies film does. There are exceptions, but
even high end digital scan backs can't compete with LF films.

Using the above method, LF film, depending on grainularity, has
the equivalent of several hundred million pixels. What you miss
is that this method is really only useful for comparing digital
with the higher quality and resolving abilities of film (i.e.,
the pixel threshold required for a minimal comparison.) It is not
a realistic comparision for film vs. digital since film has far
too many variables with regard to resolving capabilites, any of
which easily outstrips digital.

It's all pretty clear to anyone who knows that Tmax developed
in Microdol offers higher resolution of detail than Tri-X
developed in Rodinal. Or that 4x5 offers better optical
enlargments than 35mm. But there are not only Nyquist limitations
on digital, but limitations on how large sensors can get vs. how
small photodetectors can get. Any real engineer knows this...

rafe b wrote:

On 20 Jan 2006 17:25:58 -0800, "Scott W" wrote:

Tom Phillips wrote:

You guys are so utterly ignorant and unread.
24 million pixels is what photoscientists have
determined is the equivalant resolution for
400 speed 35mm color negative film.

The photscientists in your head, Tom?

You're a moron...par for the course on USENET...

"Tom Phillips" wrote in message
...

Scanned comparisions are bogus. You need to compare
a real enlargment with interpolated digital. As I said
earlier, you're not listening to what I'm saying: Enlargement
quality all depends on the optics and MTF. The scanning
[comparison] option ignores that any time you scan an image
you will either lose some detail or shift the Dmin/Dmax.

For [a film] emulsion layer, the fraction of developable grains
is plotted as a function of the number of absorbed photons in
an area equivalent to a film pixel.

What is a "film pixel"? Do you mean a film area the same size as a single
pixel sensor, or the size of the interpoated area of the sensor (which would
be 4 pixel sensors in bicubic sampling.)

[...] It is not
a realistic comparision for film vs. digital since film has far
too many variables with regard to resolving capabilites, any of
which easily outstrips digital.

Does "too many variables" really mean it's just plain hard, or is it
impossible? Would limiting outcomes to those perceivable by a human being
help? We cannot see the full range of colors captured by either color film
or a bayer filter.

Can we keep it simple for my simple mind? Put the presumptions up front.

Taking Lens: 60lp/mm
Printing Lens: 60/lpmm
My guestimate is that the maximum theoretical output will be about 45
lp/mm
Enlargement factor 10x
What is the resolving capability of the paper to the projected image?
What is the dmin/max of the film?
What is the dmin/max of the paper?
How do you measure the outcome of these factors to the final print
as, of course, perceived by the human eye. (Does it make sense to
calculate outcomes we cannot perceive?)

In article ,
rafe b rafebATspeakeasy.net wrote:

Sigh. Do what you want, Gregory. You and I seem
to be the only folks here with even the slightest interest
in the original topic, and yet even between the two
of us we can't agree on a methodology.

This isn't an experiment to prove Scheimpflug.
It's been done. It's over. It's irrelevant to what
I'm trying to achieve with this comparison.

You needn't convince or educate me on the
technical benefits of LF as compared to other
cameras and film formats. I take it as a given.
That's why I'm on this NG, okay?

Surely in your collection you have prints from
LF chromes or negatives that you feel are
sharp and representative of your best technical
efforts. So use one of those.

Why make it difficult? It's not rocket science.

Your missing my point, I was hoping to learn as much from
this as perhaps you. You misread my post as saying
that adjustment of the film plane was required, I was trying to
say leave the camera standards in their neutral setting and let the f
stop control DOF.


--
"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

greg_____photo(dot)com

On Sat, 21 Jan 2006 15:22:39 -0500, G- Blank
wrote:


Your missing my point, I was hoping to learn as much from
this as perhaps you. You misread my post as saying
that adjustment of the film plane was required, I was trying to
say leave the camera standards in their neutral setting and let the f
stop control DOF.


And I'm saying -- no need to shoot anything new
for this experiment. Use what's on hand. No
need to show anything but your best results.


rafe b
www.terrapinphoto.com

AH2 wrote:

"Tom Phillips" wrote in message
...

Scanned comparisions are bogus. You need to compare
a real enlargment with interpolated digital. As I said
earlier, you're not listening to what I'm saying: Enlargement
quality all depends on the optics and MTF. The scanning
[comparison] option ignores that any time you scan an image
you will either lose some detail or shift the Dmin/Dmax.

For [a film] emulsion layer, the fraction of developable grains
is plotted as a function of the number of absorbed photons in
an area equivalent to a film pixel.

What is a "film pixel"? Do you mean a film area the same size as a single
pixel sensor, or the size of the interpoated area of the sensor (which would
be 4 pixel sensors in bicubic sampling.)

No, as the measurement is described, it's the number
of absorbed photons in a given area.

[...] It is not
a realistic comparision for film vs. digital since film has far
too many variables with regard to resolving capabilites, any of
which easily outstrips digital.

Does "too many variables" really mean it's just plain hard, or is it
impossible? Would limiting outcomes to those perceivable by a human being
help? We cannot see the full range of colors captured by either color film
or a bayer filter.

Can we keep it simple for my simple mind? Put the presumptions up front.

Variables means film has many more options. The issue
is resolving ability. Film is simply able to resolve
finer detail than digital for several reasons, including
Nyquist limitations. But it's variable depending on
the film, granularity, optics, and developers.

Taking Lens: 60lp/mm
Printing Lens: 60/lpmm
My guestimate is that the maximum theoretical output will be about 45
lp/mm
Enlargement factor 10x

Like I've said optics are a factor and can be
a limitation. But the enlargment factor varies
with the format. Thus 8x10 blows away 35mm...

What is the resolving capability of the paper to the projected image?

Papers have such a fine grain pattern in relation
to films it's not an issue. You're not enlarging
the paper, your enlarging the negative...

What is the dmin/max of the film?
What is the dmin/max of the paper?
How do you measure the outcome of these factors to the final print
as, of course, perceived by the human eye. (Does it make sense to
calculate outcomes we cannot perceive?)

dmin/Dmax isn't an issue of resolution, but of contrast.

Tom Phillips wrote:

They're called facts. You can't generate a useable
digital image signal with just one electron. Go ahead,
ask any engineer.

Photomultiplier tubes and image intensifier tubes
(photon counters) will do that. There are excellent reasons
why these would never be used for general photography
(PMTs are not even imaging detectors) and for many
purposes they have already been replaced by CCDs.

But the reality is that it doesn't really matter whether something
generates a signal with one electron, because this is rarely
what makes or breaks it for general photography. In fact, the
quantum efficiency of film is rather low (i.e. only X% of incident
photons actually are detected and produce a signal in the latent
image, where X is ~3%). This is one reason that film has largely
been replaced by electronic detectors for very low light level
imaging. But again, this has very little to do with general
photography. I would not argue for the superiority of film based
on its ability to detect single photons. nor would I argue for the
superiority of CCDs based on their higher QE. It's just a stupid
flamewar that distracts people from making pictures.

wrote:

Tom Phillips wrote:

They're called facts. You can't generate a useable
digital image signal with just one electron. Go ahead,
ask any engineer.

Photomultiplier tubes and image intensifier tubes
(photon counters) will do that. There are excellent reasons
why these would never be used for general photography
(PMTs are not even imaging detectors) and for many
purposes they have already been replaced by CCDs.

As I've noted some CCD sans, like Imacon, give
pretty impressive results. It would depend on
the application which I would use (drum or CCD.)

But the reality is that it doesn't really matter whether something
generates a signal with one electron, because this is rarely
what makes or breaks it for general photography. In fact, the
quantum efficiency of film is rather low (i.e. only X% of incident
photons actually are detected and produce a signal in the latent
image, where X is ~3%). This is one reason that film has largely
been replaced by electronic detectors for very low light level
imaging.

Film is an excellent low light detector, in fact. It
just takes time. The quantum efficiency (intermittancy
effect) is what causes reciprocity failure at longer
exposures. This isn't a problem with most b&w films or
color films designed for extended exposure...

But again, this has very little to do with general
photography. I would not argue for the superiority of film based
on its ability to detect single photons.

I would. It's part of my general photography all the
time. Fact with film: noise isn't the issue, reciprocity
is. These are very different limiting factors. But noise
_is_ inherent in CCD or CMOS imaging especially if changes
in the so-called speed (something of a misnomer) from the
nominal digital speed producing the highest quality image
to a higher speed for low light. It's not at all a stupid
discussion. Film simply doesn't have a noise problem since
due to quantum intermittancy all you have to do is
compensate by extending the exposure. There is little if
any image degradation.

nor would I argue for the
superiority of CCDs based on their higher QE. It's just a stupid
flamewar that distracts people from making pictures.