Full resolution of film!

alanrockwood · Aug 31, 2023

Leidolf said:
And deducing the resultant resolution is much like deducing the resultant sesistance in an electrical circuit, when adding resistors in a serial coupling :
1/N1 + 1/N2 + 1/N3 etc etc

N1 being the resolution in LPM (lines pr millimetre) of the taking lens
N2 being the resolution in LPM of the film
N3 being the resolution in LPM of the enlarger lens or the projector lens

From the point of view of statistics and signal processing theory a better way to estimate the resolution of a combined system would use a formula like:

w^2=w1^2+w2^2+w3^2+...

where "w" is the width (as measured by the standard deviation) of the point spread function for the combined system and "w1" etc. are the widths of the point spread functions for the components of the system.

We can assume that 1/N is proportional to w, with 1/N1 being proportional to w1, etc.

This formula assumes that the components act independently.

If the assumption of independence holds then the formula I gave is a rigorous result that can be derived from probability theory. If independence does not hold then all bets are off.

Helge · Aug 31, 2023

faberryman said:
I thought the question in post #1 and the response in post #2 set up the issue nicely. Then it pretty much went off the rails, culminating in post #132 with a photo of a giant coffee cup that looks like a lens, which I guess was supposed to mean that if you drink too much coffee not even a Leica APO lens will achieve the full resolution of film because your hands will be shaking so much you can't hold the camera steady. Or something.

Is this really "mysterious" or do we just not have the film and lens resolution data to answer the question objectively?

The resolving power and sharpness of the different parts of the whole optical and photochemical chain and how they work together is not obvious or straightforward.

The OP question is obviously “naive”. As always it’s about asking the right question and you will only arrive at an approximation of that, after at least a few rounds around the hermeneutic spiral.

The answer in post 2 is at best “kind of correct, but…”

Not trying to be obfuscatory or mystical, just to point out the perhaps nonobvious complexity of the subject.

There are hundred of hits if you do Google searches on the related terms and some of the later posts in this thread are good too, including the above.

BrianShaw · Aug 31, 2023

... but would you add factors, multiply factors, or raise them by the power-of-two?

faberryman · Aug 31, 2023

alanrockwood said:
Many years ago, in one of the major photo magazines, I think it was Modern Photography, there was an article on achieving 100 line pairs per mm. To summarize, if one used a very good prime lens at optimal aperture, using good technique (like using a tripod) you could get very close to or even achieve 100 line pairs per mm using Panatomic X film. That was measuring resolution by the method they used at that time at that magazine.

Doesn't make sense to me. I looked at some old Modern Photography lens tests and no lens I looked at approached 100 l/mm. For example, the Leica Summilux-R 50mm f/1.4, which by all accounts is a pretty good lens, achieved its best center performance of 76 l/mm at f/5.6 and f/8. Resolution was lower at other apertures. I do not know how Leidolf came up with a resolution of "1000" for a "Leica lens".

Then there is film resolution. For example, Kodak lists two resolutions for TMax 100: 63 lines/mm (TOC 1.6:1) and 200 lines/mm (TOC 1000:1). Which one does one use and why? Are other films measured in the same manner (ISO 6328)?

I have a strong suspicion that there are a lot of apples and oranges comparisons being made.

Sirius Glass · Aug 31, 2023

From a course I took at Kodak: Everything in the image chain: filters, lenses, shutters, development, image processing, et al contributes to the final result and can only be improve to the best the weakest part of the image chain. Without improving the weakest part, no improvements will improve the image significantly.

r_a_feldman · Aug 31, 2023

chuckroast said:
Modern zooms are hands down better in almost every way than the old manual focus Nikkors.
It is almost certain that some of the primes have better correction. For example, my 35mm f/1.4 Ai-S is lovely stopped down but has a lot of visible coma wide open. It is reported - not confirmed by me personally - that the newer autofocus variant of this lens corrects considerably for this.

While many modern lenses benefit greatly from things like aspheric elements, others achieve their corrections through the computers in the camera digitally correcting the image after it is captured. DP Review, shortly before it was closed down, stated that their reviews would evaluate lenses based on the in-camera corrections, not on the raw characteristics of the lenses.

faberryman · Aug 31, 2023

Sirius Glass said:
From a course I took at Kodak: Everything in the image chain: filters, lenses, shutters, development, image processing, et al contributes to the final result and can only be improve to the best the weakest part of the image chain. Without improving the weakest part, no improvements will improve the image significantly.

A little internet research reveals that the idiom “a chain is no stronger than its weakest link" first appeared in Thomas Reid’s Essays on the Intellectual Powers of Man published in 1786. So it's not like Kodak was coming up with something new. More like they were stating the obvious. And I bet you knew it long before walking into the course.

Sirius Glass · Aug 31, 2023

faberryman said:
A little internet research reveals that the idiom “a chain is no stronger than its weakest link" first appeared in Thomas Reid’s Essays on the Intellectual Powers of Man published in 1786. So it's not like Kodak was coming up with something new. More like stating the obvious.

But Kodak applied that to photography and never made a claim as to being the originator of the concept.

DREW WILEY · Aug 31, 2023

So darn much of this Pop Photo and DIY subjective film/ lens MTF chatter sounds a lot like how the more fatigued the eyes of Percival Lowell became, the more canals he saw on the surface of Mars!

About all I can say at this point, is that they company 10 minutes up the highway who is the leading manufacturer of aspheric lenses and mirrors in the world, would unquestionably have a different opinion about how to measure and quantify such things.

faberryman · Aug 31, 2023

Sirius Glass said:
But Kodak applied that to photography and never made a claim as to being the originator of the concept.

I'll let you award the trophy.

Sirius Glass · Aug 31, 2023

faberryman said:
I'll let you award the trophy.

I was providing information. I do not know what you were providing.

faberryman · Aug 31, 2023

Sirius Glass said:
I was providing information. I do not know what you were providing.

Perspective on the information provided.

BrianShaw · Aug 31, 2023

DREW WILEY said:
So darn much of this Pop Photo and DIY subjective film/ lens MTF chatter sounds a lot like how the more fatigued the eyes of Percival Lowell became, the more canals he saw on the surface of Mars!

About all I can say at this point, is that they company 10 minutes up the highway who is the leading manufacturer of aspheric lenses and mirrors in the world, would unquestionably have a different opinion about how to measure and quantify such things.

Why don’t you ask them to stop by and give us the answer, or at least their opinion. Otherwise, so what; who cares? Respectfully asked, of course.

DREW WILEY · Aug 31, 2023

Because nobody on this forum would even understand the damn answer! How many real optical engineers are chiming in here? Zero or less than zero? I've at least worked alongside some of them, and interacted numerous times with the big mfgs themselves in terms of measuring equipment. And I don't pretend to know the physics, just some of the instrumentation, which makes every single thing stated so far here seem medieval.

But I really meant it, what I stated about casual MTF readings. Eye fatigue easily become a huge factor skewing any real objectivity. Throw in non-flat film, the kitchen sink, and who can trust much of any of it that makes its way onto the web?

BrianShaw · Aug 31, 2023

Ya, I know what you mean. So much stuff on the web is so unbelievable… a lot of hot air and obfuscation yet little meaningful content.

bluechromis · Aug 31, 2023

There is the resolution of lenses overall, but there is also the resolution in different regions of the image. Because perceived sharpness is heavily influenced by the difference between the sharp and not sharp areas of an image, I am not concerned if a lens is a bit soft at the edges. I'm talking about a subtle difference here that might be found between basic lenses and super high-end lenses. The difference in cost and complexity between a lens that is sharp in the middle and the majority of the image and one that is sharp all the way to the edges can be considerable. If you want a lens with a wide aperture, is sharp to the edges, and is a zoom, the complexity explodes, and you get lenses with a ridiculous number of elements. I find it hard to believe there isn't some kind of downside in image quality from such complexity. This is a matter of taste, but what matters to me is that the main subject is sharp and it's not worth paying a premium for lenses that are tack sharp in every millimeter of the image.

Nikon 2 · Aug 31, 2023

Shows just how much we know about what, if any lens, can resolve all the information embedded in the finest grain film…!

bluechromis · Aug 31, 2023

Sirius Glass said:
From a course I took at Kodak: Everything in the image chain: filters, lenses, shutters, development, image processing, et al contributes to the final result and can only be improve to the best the weakest part of the image chain. Without improving the weakest part, no improvements will improve the image significantly.

This is why I appreciated someone mentioning the importance of using a tripod. I see in so many forums, not so much Photrio, where some beginner asks something like, "What's the sharpest lens for Nikon, or Canon etc.?" What they might be asking really is what is the best lens, but ultimately they are asking "What will make my pictures look better?" and thinking that the answer is getting the sharpest lenses. Of course, the marketing of lens makers does nothing to disabuse them of that assumption. Then the forum discussion meanders off into rabbit holes about minute differences in sharpness between lenses. Seldom does anyone mention that if resolution and sharpness are wanted, the most effective way to do that is to use a tripod.

wiltw · Sep 1, 2023

faberryman said:
Doesn't make sense to me. I looked at some old Modern Photography lens tests and no lens I looked at approached 100 l/mm. For example, the Leica Summilux-R 50mm f/1.4, which by all accounts is a pretty good lens, achieved its best center performance of 76 l/mm at f/5.6 and f/8. Resolution was lower at other apertures. I do not know how Leidolf came up with a resolution of "1000" for a "Leica lens".

And that is why the normal ratings (IIRC the numbers)
Excellent = 84 lp/mm
Good = 64 lp/mm
Exceptional > 100 lp/mm
...and as I recall there was one lens that achieved 120 lp/mm

I gotta pull out an old magazine when I back home, to verify the threshholds.

alanrockwood · Sep 1, 2023

faberryman said:
Doesn't make sense to me. I looked at some old Modern Photography lens tests and no lens I looked at approached 100 l/mm. For example, the Leica Summilux-R 50mm f/1.4, which by all accounts is a pretty good lens, achieved its best center performance of 76 l/mm at f/5.6 and f/8. Resolution was lower at other apertures. I do not know how Leidolf came up with a resolution of "1000" for a "Leica lens".

Then there is film resolution. For example, Kodak lists two resolutions for TMax 100: 63 lines/mm (TOC 1.6:1) and 200 lines/mm (TOC 1000:1). Which one does one use and why? Are other films measured in the same manner (ISO 6328)?

I have a strong suspicion that there are a lot of apples and oranges comparisons being made.

I apologize. I relied on memory in making my post. I offer a correction below.

First of all, I found the article. It is in Modern Photography, October, 1978. The article starts on p. 108. The title of the article is "How Sharp Can You Get?". The authors were Bennett Sherman and Al Gordon.

They did not achieve 100 LPM using Panatomic X. With Panatomic X the best results were at infinity focus with the apertures set at f/4 for six different lenses. The results and resolution in lines/mm were as follows:

Sumicron 50mm f/2 lens: 88 at f/4
Nikor 50mm f/1.8 lens: 88 at f/4
Canon 50mm f/1.8 lens: 86 at f/4
Minolta 50mm f/1.7 lens: 86 at f/4
Pentax 50mm f/1.7 lens: 86 at f/4
Olympus 50mm f/1.8 lens: 86 at f/4

With Tech Pan film focused at infinity the results were a little better for the same lenses, ranging from 92 lines/mm to 96 lines/mm.

High contrast Copy film did a little better, reaching 102 to 106 lines/mm.

For Kodachrome II the results ranged from 80 to 86 lines/mm.

For Micro-Ektachrome the results ranged from 100 to 102.

They also tested some close focusing and macro lenses under under close up conditions. I couldn't quite figure out exactly what those close up conditions were. However, the results were somewhat less sharp than the tests of the 50mm prime lenses at infinity, roughly 10% lower resolution.

That same issue of Modern Photography also had an article addressing that age old question "Can you really "push" film???" I won't comment on that, except to say that their conclusion could be summarized with the somewhat vague characterization of "yes, sort of." (Not a quote from their article, but my condensed version of how I interpret their results.)

Alan Johnson · Sep 1, 2023

Welcome to Erwin's Photosite, technical part

Erwin Puts was a Leica expert with an interest in lens and film resolution.

George Mann · Sep 1, 2023

Nikon 2 said:
Is it true in order to get the full resolution of the highest grain film, one must have a lens capable of allowing this? So maybe a Leica 50mm f/2 APO ASPH should be the type of lens needed to get all the resolution from film…!

My Nikkor 50mm f/2's resolve an incredible amount of detail.

I have never needed more.

George Mann · Sep 1, 2023

Nikon 2 said:
My poor Nikkor lenses aren’t close to those rich Leica lenses in resolving film to the fullest…!

I thought you had a 50mm f/2? Are you shooting wide open?

Nikon 2 · Sep 1, 2023

George Mann said:
My Nikkor 50mm f/2's resolve an incredible amount of detail.

I have never needed more.

It is said they are one of the sharpest Nikkor lenses…!

Nikon 2 · Sep 1, 2023

Alan Johnson said:
Welcome to Erwin's Photosite, technical part
Erwin Puts was a Leica expert with an interest in lens and film resolution.

That’s what I’m talking about…!

Full resolution of film!

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