The Maths of a Fine B&W Print

Sandy;

I agree, and that is probably when he stopped reading this thread.

I've grown exhausted by hitting the books over this myself and should have kept my mouth shut, since in the end, it has probably done nothing and your advice is still the best.

PE

I wonder if this MTF was researched by Kodak and forgotten or neglected for other reasons.In the following (Q28) it is mentioned that SQF (subjective quality factor) is an objective measurement that correlated well with subjective ratings of print quality.Simplified it is the MTF in the print averaged from 0.5 to 2 cycles per mm.This work is attributed to Ed Grainger of Kodak.
http://www.faqs.org/faqs/rec-photo/lenses/faq/

MTF is still used as are a number other measurments.

PE

Jed Freudenthal said:

The Zeiss study has been published around, I would say, 1995/6. As a result of that study, a special apparatus with a microscope has been build to measure film flatness directly. This apparatus is used since around 2000. Therefore, I am referring to the start of the study by Zeiss. As a result, Rollei modified the back of my SLX in their factory, but that is an action in between. The back of the 6008 is completely different from the back of the original SLX.

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Interesting, if OT for this thread, in view of the fact that the 6003 that I purchased in 2003 had to be returned to the distributor for service because the film plane was slightly off, resulting in focus problems. I was told that it had been assembled at the factory with the wrong film stage.

Alan Johnson said:

I wonder if this MTF was researched by Kodak and forgotten or neglected for other reasons.In the following (Q28) it is mentioned that SQF (subjective quality factor) is an objective measurement that correlated well with subjective ratings of print quality.Simplified it is the MTF in the print averaged from 0.5 to 2 cycles per mm.This work is attributed to Ed Grainger of Kodak.
http://www.faqs.org/faqs/rec-photo/lenses/faq/

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If every good print has SQF avove a certain value and every poor print has SQF below a certain value, it might be perfect correlation or a poor experiment. I would expect Kodak researchers to know that, and to try to find poor prints with good scores and good prints with poor scores. The question in any case would only help the original poster if analog photos had good scores a preponderence of the time while digital photos had lower scores on the same subject matter. I doubt that one would ever find that to be true in comparing professional quality photos of both types in the 0.5 to 2 cycles per mm band.

Difference In detail Between Film & Digital

I am coming to this thread very late and it has taken some time to read all of the postings. I don't know just how much science the original question called for but the responses certainly made for interesting and entertaining reading. In the simplest terms, a negative will show dark and light areas of a scene in proportion to the amount of light which has struck the film in each area. The extent to which a wide range of tones can be recorded is now referred to in digital photography as dynamic range. Many factors go into the extent of the dynamic range in black & white negatives and final prints. They include, but are not limited to, the speed and grain characteristics of the film chosen, the method used to develop the film, the contrast and quality of the light when the image was made, the contrast and quality of both the taking lens and the enlarging lens, the contrast, optical flatness and surface characteristics of the paper the print is made on and the chemistry used in the print making process. If the question was more about detail in general then we would address things like grain size, the degree to which each film format must be enlarged to reach a certain print size and perhaps the optical properties of the taking and enlarging lenses. If the question is aimed more at dynamic range or specifically at the details which can be shown at the opposite ends of the dynamic range then many other factors come into play.

As a practical matter most people who make their own black & white prints from negatives do not regularly resort to MTF figures or use a densitometer. It's not that such things couldn't be used but with practice you can get the type of image you are looking for if you are using the right film, chemistry and equipment for the job. If a photograher had to make hundreds of prints from the same negative and had to make sure they were all nearly identical then very careful procedures would have to be followed to assure consistency. The introduction of scientific measuring tools like MTF tests to answer a relatively simple question is a sign that spreadsheet analysis has its limits. Many years ago I worked with a colleague who was young and long on good looks and charm but short on maturity. He was dating several women and decided to make up a spreadsheet to help him decide which one or ones he should keep dating. I don't think he came up with any useful conclusions even though he had included a long list of attributes. I could read that a drag racer has 700 horsepower and hits 100 MPH in a very short time. This tells me the drag racer has better acceleration than my Honda but it doesn't tell me whether the drag racer is better in general for my purposes. Testing measures can be very useful in comparing one particular attribute of a product to the same attribute in another similar product but there is some overall feel for the difference which will always be made at least in part based on subjective measures.

I once told a friend about my experimentation with Kodak Imagelink film (don't worry, I still have plenty of TP in the freezer). His response was that if I needed to make a large print, I should just put some Plus-X into a medium format camera. A large print could be made easily and predictably that way. I have an old Leica brochure in which the issues of lenses with and without floating elements are discussed. At the time Leica thought designs without floating elements (mostly wide angles) could still compete against designs with them. In certain MTF tests the floating element designs looked better but those tests did not tell the whole story. The whole issue of sharpness is quite complicated and has been discussed in threads here and at photo.net in great detail. Some of the poster's original question could be answered by reading through these old threads. I agree that divining artistic merit through the results of scientific testing will always be difficult and probably not desirable.

gainer said:

If every good print has SQF avove a certain value and every poor print has SQF below a certain value, it might be perfect correlation or a poor experiment. I would expect Kodak researchers to know that, and to try to find poor prints with good scores and good prints with poor scores. The question in any case would only help the original poster if analog photos had good scores a preponderence of the time while digital photos had lower scores on the same subject matter. I doubt that one would ever find that to be true in comparing professional quality photos of both types in the 0.5 to 2 cycles per mm band.

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Subjective Quality Factor (SQF) has been introduced by Ed Granger (Kodak research labs) and is not what you think it is.
For a meaningful discussion, we really have to go to the reports of the studies done in the area of image quality. And that seems to be a problem. In one case, the publications cannot be obtained, because there are no relations with a library, in another case it is too much work to go through the books, then a European study might be not thorough, in another case the description or study doesn't cover every aspect.. In this way, Einstein with his theory of relativity did a poor job: it was a German study, it didn't cover every aspect of nature, and after all it got a European prize, the Nobel prize. It cannot never be a good study.
But, I also think the work of Ed Grainer at Kodak cannot be neglected. Grainer has been chairman on conterences on the subject of image quality. Grainer is considered as an authority in this field.
On the other hand, this thread got much attention. Therefore, I would say: it is an important subject for many Apuggers. To that end I will give a reference to an introductory and well written paper of Bob Atkins on SQF and MTF. On MTF, you can find more introductory texts.
http://www.bobatkins.com/photography/technical/mtf/mtf1.html
This text might be the start of a more extensive study in the subject of image quality.

Jed

dynachrome said:

... Many years ago I worked with a colleague who was young and long on good looks and charm but short on maturity. He was dating several women and decided to make up a spreadsheet to help him decide which one or ones he should keep dating. I don't think he came up with any useful conclusions even though he had included a long list of attributes.

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Why not??? Seems to make as much sense (possibly even more) as obsessing about "MTF".

Paraphrasing Farragut in the Battle of Manila: "DAMN the MTFs!! - FULL photographing speed ahead!!"

... That slogan belongs in the f/63 Group.

Einstein's Nobel Prize was not for his Theory of Relativity. Look it up. It had to do with photoelectric work function. Neither that nor his Relativity Theory was a study. It was pure theoretical genius. He later regretted having included an arbitrary constant in that theory. His prediction of bending of light rays by gravity as they passed near the sun which was found to be true during a total eclipse and his explanation of "anomalies" in the orbit of Mercury by calculations from his theory of Relativity did not enter into his theory but were derived from it. A good friend of his, mathematical physicist Kurt Godel (should be umlaut over the o) proved a very important theorem of mathematical logic. Any system of axioms at least as rich as arithmetic is either incomplete or inconsistent. You, Jed, should study that theorem and its consequences.

Jed Freudenthal said:

Subjective Quality Factor (SQF) has been introduced by Ed Granger (Kodak research labs) and is not what you think it is. On MTF, you can find more introductory texts.
http://www.bobatkins.com/photography/technical/mtf/mtf1.html
This text might be the start of a more extensive study in the subject of image quality.

Jed

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What I thought it was is what PE said it was.
None of which is pertinent to the original post because the very same lens can be and in fact often is used on both film and digital cameras. How will the MTF of that lens differentiate between the digital and film recordings of its output? Unless you can point us to studies of relative MTF's of film and digital photographs of the same subject through the same lens that show that there are measurable differences, the MTF is not what our original poster was looking for nor what he can use to prove his point.

The MTF, whether in temporal or spacial data transmission, is the Fourier transform of the system response to a unit impulse, which is strictly speaking unobtainable. The narrowest possible slit is the best possible approximation to that method.

Actually, if you look at a lot of research, the researchers are very interested in IC (Information Capacity) and this includes the entire system response so it cascades the lens, camera, film (or sensor), paper (or any viewing method) and eye together in one large function that expresses IC or "H". Terms in this include MTF as just a minor function of the overall math of the total system. MTF of the film or camera alone is not a major criterion in this calculation.

Concern over MTF is just a single footnote in the overall math of IC which is what the human sees or percieves.

And, btw, going back to Patricks comment earlier, I saw two missle launches at the Cape where Roll, Pitch and Yaw were exchanged. Unlike Patricks pilot, the auto guidance system was unable to compensate.

In one case, a Mace, the missile left the silo and observed that it was 'upside down' and promptly rolled over and few into the ground. In the other, a Blue Scout, the missile went into violent barrel rolls trying to compensate and finally broke into 3 stages (parts) and crashed.

Human input, as Patrick implied, is more important than cold calculation. That seems to be the sum of all of this.

PE

Ah yes - then there is the happy accident where human intuition based on years of experience made a good wild guess. - I try to limit that sort of thing myself but it is nice when it happens.

Link about MTF

Do you have any links to suggest?

Jed Freudenthal said:

The transfer of any image is described with the Modulation Transfer Function (MTF) . This applies to analogue and digital photography, but also to many other optical systems. The MTF describes the quality of the transferred image. It is done with a mathematical function, but is part of physics. When you want to know the difference in the quality between specified analogue and digital photographic processes, all you have to do is to compare the MTF's of both systems. The result is often that the details ( high spatial frequencies) are lost in digital photography.
The use of MTF is common in photography, but photographers don't use it very much. This is strange because by using MTF, the process is better under control. e.g. the selection of lens and film is optimized.

Jed

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fhovie said:

Ah yes - then there is the happy accident where human intuition based on years of experience made a good wild guess. - I try to limit that sort of thing myself but it is nice when it happens.

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We called that a "WAG" or Wild Assed Guess. Others called it intuition.

The last thing you ever want to hear is your pilot say "OOPS"!

PE

Or the announcement over the PA: "There is nothing to worry about. This aircraft is automatically controlled. Nothing can go wrong....go wrong.....go wrong...

Photo Engineer said:

We called that a "WAG" or Wild Assed Guess. Others called it intuition.

The last thing you ever want to hear is your pilot say "OOPS"!

PE

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Do you remember Herb Schultz? Kodak pilot -- and Frances's (alas, late) uncle...

Cheers,

R.

Roger;

I few to Tennesee Eastman with Carl Kohrt once on Kodak Air. That was it. For all the rest I went commercial. I don't remember the pilot's name, but he was a rather short balding individual in his 40s or thereabouts and that was in about 1975.

He was very nice and we had a chat before takeoff and ate rolls and had some coffee that he brought in for all of us who were flying with him. He had a tray set out at the front of the plane, and a small urn of coffee. I seem to remember that the coffee was there and he brought in the tray of rolls.

He said he was chief steward and pilot on the flight or something like that. Very nice person.

My boss, who was a pilot before coming to Kodak actually got to sit in the co-pilots seat for part of one of his trips, much to the consternation of some of the passengers. The pilot came out and said "Ok Charlie, its your turn in the hot seat" or something like that.

These old stories are always fun to remember.

PE

gainer said:

Einstein's Nobel Prize was not for his Theory of Relativity. Look it up. It had to do with photoelectric work function. Neither that nor his Relativity Theory was a study. It was pure theoretical genius. He later regretted having included an arbitrary constant in that theory. His prediction of bending of light rays by gravity as they passed near the sun which was found to be true during a total eclipse and his explanation of "anomalies" in the orbit of Mercury by calculations from his theory of Relativity did not enter into his theory but were derived from it. A good friend of his, mathematical physicist Kurt Godel (should be umlaut over the o) proved a very important theorem of mathematical logic. Any system of axioms at least as rich as arithmetic is either incomplete or inconsistent. You, Jed, should study that theorem and its consequences.

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Oh, you are one of the intuitionists. I thought they do not exist anymore. I did not expect to get at that point in APUG. At least, I know you are no Hilbertian or Einsteinian or at least that part of mathematical physics, that made the physics of today. I do not think the APUG is the place to go into this science that has found its end in 1929 by the Springer editors of the Mathematische Annalen by firing the intuionist Brouwer as one of the editors ( or actually replacing all editors , like Einstein, Hilbert etc. except Brouwer). I know the Goedel theorem, you are referring to, but I prefer another way of thinking. Mathematical Physics should describe the observations in nature. But Gadget, all these things are more for a private communication than for APUG members. I think, the description of the human vision by Grainer of Kodak with his SQF is more relevant.

Jed
The

Photo Engineer said:

...He said he was chief steward and pilot on the flight or something like that. Very nice person...
PE

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Probably not Herbie, though that sounds like his style. He died a couple of years back in his 90s, so I reckon he'd have been nearing retirement age in the mid-70s. After WW2 he and his brother (Frances's other uncle, who later flew for Ashland Oil) used to ferry DC3s down to Central America and come back on commercial flights. I sometimes wonder how many of those old Gooney Birds are STILL being used for drug smuggling...

Cheers,

R.

Jed Freudenthal said:

Oh, you are one of the intuitionists. I thought they do not exist anymore. I did not expect to get at that point in APUG. At least, I know you are no Hilbertian or Einsteinian or at least that part of mathematical physics, that made the physics of today. I do not think the APUG is the place to go into this science that has found its end in 1929 by the Springer editors of the Mathematische Annalen by firing the intuionist Brouwer as one of the editors ( or actually replacing all editors , like Einstein, Hilbert etc. except Brouwer). I know the Goedel theorem, you are referring to, but I prefer another way of thinking. Mathematical Physics should describe the observations in nature. But Gadget, all these things are more for a private communication than for APUG members. I think, the description of the human vision by Grainer of Kodak with his SQF is more relevant.

Jed
The

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I'm not sure that Goedel's undecidabilty theorems have much to do with mathematical physics, but they started a line of research passing through Turing, von Neumann and others, into the mathematical science of computational complexity which has profound consequences for modern computer programming. Brouiwer's fixed point theorem (or its corrollaries) is often the only way to demonstrate the convergence of non-linear algorithms. Both Goedel and Brouwer had a significant effect on modern thought. Poincare was also an intuitionist, and look at the way his work on differential manifolds has become a mainstream part of chaos theory.

While Goedel was at Princeton, he came up with a new solution to the Schroedinger equation, which is also supposed to be a description of nature.

Mathematics and physics have moved on, but the influence of the intuitionists remains.

I think it interesting that Jed bypassed his lack of knowledge of the true reason for Einstein's Nobel prize with a deflection into another area with further obfuscation. In addition, his apparent non-reaction to Image Content is rather interesting even though it is a major way of describing a picture of any sort.

As far as I'm concerned, the physics and math of today are being shaped by people like Edward Witten, and to a certain extent Steven Hawking. As one wag said when Witten recieved an award recently "On this subject, all is not yet Witten".

There is a lot to be discovered out there. But the imagination of humanity will shape it into something useful. Math will only be somewhat descriptive of it.

PE

Photo Engineer said:

I think it interesting that Jed bypassed his lack of knowledge of the true reason for Einstein's Nobel prize with a deflection into another area with further obfuscation. In addition, his apparent non-reaction to Image Content is rather interesting even though it is a major way of describing a picture of any sort.

As far as I'm concerned, the physics and math of today are being shaped by people like Edward Witten, and to a certain extent Steven Hawking. As one wag said when Witten recieved an award recently "On this subject, all is not yet Witten".

There is a lot to be discovered out there. But the imagination of humanity will shape it into something useful. Math will only be somewhat descriptive of it.

PE

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Thre is quite a lot to answer in this thread. Now the Nobel prize of Albert Einstein. Einstein got the Nobel prize for the totality of his work in theoretical Physics. That were three areas. [The theory of relativity was the best known part].


The exact answer can be found in the speech of Arrhenius. Here is the first part of the Nobel speech:

Presentation Speech
Presentation Speech by Professor S. Arrhenius, Chairman of the Nobel Committee for Physics of the Royal Swedish Academy of Sciences, on December 10, 1922*
Your Majesty, Your Royal Highnesses, Ladies and Gentlemen.

There is probably no physicist living today whose name has become so widely known as that of Albert Einstein. Most discussion centres on his theory of relativity. This pertains essentially to epistemology and has therefore been the subject of lively debate in philosophical circles. It will be no secret that the famous philosopher Bergson in Paris has challenged this theory, while other philosophers have acclaimed it wholeheartedly. The theory in question also has astrophysical implications which are being rigorously examined at the present time.

Throughout the first decade of this century the so-called Brownian movement stimulated the keenest interest. In 1905 Einstein founded a kinetic theory to account for this movement by means of which he derived the chief properties of suspensions, i.e. liquids with solid particles suspended in them. This theory, based on classical mechanics, helps to explain the behaviour of what are known as colloidal solutions, a behaviour which has been studied by Svedberg, Perrin, Zsigmondy and countless other scientists within the context of what has grown into a large branch of science, colloid chemistry.

A third group of studies, for which in particular Einstein has received the Nobel Prize, falls within the domain of the quantum theory founded by Planck in 1900. This theory asserts that radiant energy consists of individual particles, termed "quanta", approximately in the same way as matter is made up of particles, i.e. atom.....

I hope this will answer this question.

Jed

Pete H said:

Mathematics and physics have moved on, but the influence of the intuitionists remains.

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May be in mathematics, there is still some influence of the intuitionists. But in (theoretical) physics I cannot see such an influence. And we are considering image quality, which I think is part of physics. Therefore, I think the three research groups investigating the subject of image quality, were following the research lines of physics.


Jed

Jed Freudenthal said:

Thre is quite a lot to answer in this thread. Now the Nobel prize of Albert Einstein. Einstein got the Nobel prize for the totality of his work in theoretical Physics. That were three areas. [The theory of relativity was the best known part].

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No, he got the Nobel price for his work on the Photoelectric Effect, as is evident from the snip you quoted. The theory of relativity was still too controversial. So even if there was widespread consensus that he deserved a Nobel price, it was decided to award it for the Photoelectric Effect which was both sufficiently important and easily verifiable.

Ole said:

No, he got the Nobel price for his work on the Photoelectric Effect, as is evident from the snip you quoted. The theory of relativity was still too controversial. So even if there was widespread consensus that he deserved a Nobel price, it was decided to award it for the Photoelectric Effect which was both sufficiently important and easily verifiable.

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The formulation of the Nobel committee is as follows:
"for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect"

Einstein got the prize for the totality, but the Photoelectric Effect is especially mentioned. In the speech of Arrherenius, however, the theory of relativity is on the first place, because of its importance.

Jed