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Equivalence Theory

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Interesting reading. Maybe not anything new for dpr readers but confirms in a scientifical way many photographers experiences regarding equivalence from different cameras, including my own from MF, FF, APS-C, compacts and mobile phones.

Thanks for posting!
 
Of course, we all know who really invented "equivalence". Joltin' Joe relaxing in his "think tank":

5e6af3a687e043a98eabb2c7a330375b.jpg

:P
 
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The author is obviously aware of the discussions here (see the references) and refers to Joe's essay briefly without giving it all the credit it deserves. I find this statement curious:

Equivalence theory has previously been justified using approximate proofs that assume focus is set at infinity and use simplified formulae for the AFoV and DoF. Consequently, such approximate proofs fail to take into account the fact that the relationship between equivalent focal lengths and between equivalent f-numbers is actually dependent on the distance to the object plane upon which focus is set.

There is no reference and the statement is incorrect. Focused at infinity, the DOF is the hyperfocal distance and when talking about equivalence, nobody really means that. Perhaps he means is that eq. FLs are computed with infinity focus in mind but the DOF is computed with focus not at infinity. Next, Wikipedia mentions a 1976 book by Stroebel where the DOF for different formats is compared (for the first time?), and he does not mention it. Finally, there is also this thread and this one with more precise formulas.

Next, he claims that his proof is exact, which is questionable, at least. Nothing in optics is exact.
 
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J A C S said:
The author is obviously aware of the discussions here (see the references) and refers to Joe's essay briefly without giving it all the credit it deserves. I find this statement curious:

Equivalence theory has previously been justified using approximate proofs that assume focus is set at infinity and use simplified formulae for the AFoV and DoF. Consequently, such approximate proofs fail to take into account the fact that the relationship between equivalent focal lengths and between equivalent f-numbers is actually dependent on the distance to the object plane upon which focus is set.

There is no reference and the statement is incorrect. Focused at infinity, the DOF is the hyperfocal distance and when talking about equivalence, nobody really means that. Perhaps he means is that eq. FLs are computed with infinity focus in mind but the DOF is computed with focus not at infinity. Next, Wikipedia mentions a 1976 book by Stroebel where the DOF for different formats is compared (for the first time?), and he does not mention it. Finally, there is also this thread and this one with more precise formulas.

Next, he claims that his proof is exact, which is questionable, at least. Nothing in optics is exact.
Click to expand...
He is citing Dpreview articles, I am not sure that is equivalent to being aware of forum discussion ;)
Nice to see Joseph James, Emil Martinec and Bill Claff cited
 
J A C S said:
Next, he claims that his proof is exact, which is questionable, at least. Nothing in optics is exact.
Click to expand...
I feel it only makes sense to discuss subjects like these with a clear scope upfront. Such as 'thin perfect lenses'.

Keeping the actual lens implementation separate may or may not be the best thing, but it is way better than doing an 'ideal lens' discussion where someone comes up with 'yes but lenses have thickness and the Ooblox 30/7 is a fine lens'.
 
Sympa said:
J A C S said:
Next, he claims that his proof is exact, which is questionable, at least. Nothing in optics is exact.
Click to expand...
I feel it only makes sense to discuss subjects like these with a clear scope upfront. Such as 'thin perfect lenses'.

Keeping the actual lens implementation separate may or may not be the best thing, but it is way better than doing an 'ideal lens' discussion where someone comes up with 'yes but lenses have thickness and the Ooblox 30/7 is a fine lens'.
Click to expand...
BTW, the often cited here Zeiss document (author Nasse) has MTF measurements of actual lenses (Zeiss, of course). There are significant DOF differences among different types of lenses, with DOF based on MTF criteria.
 
BobORama said:
Great, now we have to suffer a decade of people referencing the article without having read it saying "See! Equivalence is a thing!"
Click to expand...
Seems only fair after a decade (or so) of people saying they never saw equivalence referred to in their favorite photography "how to" books and saying "See! Equivalence isn't a thing!"
 
What is ironic about the article is that its premise is contradicted by the other favorite topic of the pseudoscience set : ISO invariance.

Luckily, the fantasy logic and wishful thinking of these people does not affect the way cameras work in the real word.
 
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SmilerGrogan said:
What is ironic about the article is that its premise is contradicted by the other favorite topic of the pseudoscience set : ISO invariance.

Luckily, the fantasy logic and wishful thinking of these people does not affect the way cameras work in the real word.
Click to expand...
Sanctimonious phonies usually have a way of vaingloriously self-hoisting by their own petards.
 
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SmilerGrogan said:
What is ironic about the article is that its premise is contradicted by the other favorite topic of the pseudoscience set : ISO invariance.
Click to expand...
Why would one model contradict the other? They are not intended to cover the same range of exposure.
SmilerGrogan said:
Luckily, the fantasy logic and wishful thinking of these people does not affect the way cameras work in the real word.
Click to expand...
That is the nature of simplified models: They don't explain every single detail, they explain the basic principles.

Gruß, masi1157
 
Equivalence theory is like teaching Latin to high school students, it’s interesting and a good workout for the brain but it’s relevance is quickly diminishing.

As the author of that paper points out, the theory can’t stand up to computational photography, and all digital cameras are computational. It’s only going to get worse as camera makers put more horsepower into cameras and start to innovate with lenses.

I enjoy harmless crackpottery as much as the next person but this intellectual catastrophe has negative consequences such as convincing the gullible to believe nonsense like there is no correct exposure.

But that is the way of the West now, we are mesmerized by the promise of transgressions and paradigm-shattering and blind to reality, which is why the Chinese were able to send cameras to the dark side of the moon while we were busy keeping up with the Kardashians.


masi1157 said:
SmilerGrogan said:
What is ironic about the article is that its premise is contradicted by the other favorite topic of the pseudoscience set : ISO invariance.
Click to expand...
Why would one model contradict the other? They are not intended to cover the same range of exposure.
SmilerGrogan said:
Luckily, the fantasy logic and wishful thinking of these people does not affect the way cameras work in the real word.
Click to expand...
That is the nature of simplified models: They don't explain every single detail, they explain the basic principles.

Gruß, masi1157
Click to expand...
 
J A C S said:
The author is obviously aware of the discussions here (see the references) and refers to Joe's essay briefly without giving it all the credit it deserves. I find this statement curious:

Equivalence theory has previously been justified using approximate proofs that assume focus is set at infinity and use simplified formulae for the AFoV and DoF. Consequently, such approximate proofs fail to take into account the fact that the relationship between equivalent focal lengths and between equivalent f-numbers is actually dependent on the distance to the object plane upon which focus is set.

There is no reference and the statement is incorrect. Focused at infinity, the DOF is the hyperfocal distance and when talking about equivalence, nobody really means that. Perhaps he means is that eq. FLs are computed with infinity focus in mind but the DOF is computed with focus not at infinity. Next, Wikipedia mentions a 1976 book by Stroebel where the DOF for different formats is compared (for the first time?), and he does not mention it. Finally, there is also this thread and this one with more precise formulas.

Next, he claims that his proof is exact, which is questionable, at least. Nothing in optics is exact.
Click to expand...
I'm not so familiar with how SPIE works, but IEEE Antennas and Propagation has seperate publications for full journal papers, letters, and then a magazine for articles like this one. To quote:

"The IEEE Antennas and Propagation Magazine actively solicits feature articles that describe engineering activities taking place in industry, government, and universities. All feature articles are subject to peer review. Emphasis is placed on providing the reader with a general understanding of either a particular subject or of the technical challenges being addressed by various organizations, as well as their capabilities to cope with these challenges. Articles presenting new results, review, tutorial, and historical articles are welcome, as are articles describing examples of good engineering."
 
SmilerGrogan said:
Equivalence theory is like teaching Latin to high school students, it’s interesting and a good workout for the brain but it’s relevance is quickly diminishing.
Click to expand...
Yeah, like gravity.
SmilerGrogan said:
As the author of that paper points out, the theory can’t stand up to computational photography, and all digital cameras are computational. It’s only going to get worse as camera makers put more horsepower into cameras and start to innovate with lenses.

I enjoy harmless crackpottery as much as the next person but this intellectual catastrophe has negative consequences such as convincing the gullible to believe nonsense like there is no correct exposure.

But that is the way of the West now, we are mesmerized by the promise of transgressions and paradigm-shattering and blind to reality, which is why the Chinese were able to send cameras to the dark side of the moon while we were busy keeping up with the Kardashians.
Click to expand...
en.wikipedia.org

List of NASA missions - Wikipedia

en.wikipedia.org en.wikipedia.org
 
John Kot said:
Detail Man said:
Of course, we all know who really invented "equivalence". Joltin' Joe relaxing in his "think tank":

5e6af3a687e043a98eabb2c7a330375b.jpg

:P
Click to expand...
Maybe Joe should've called it "Relativity" rather than "Equivalence":

FF = (µ 4/3)^2

That sorta thing...
Click to expand...
I have pointed out to him that the term "Equibblence" might be a more apt descriptor of how "F2=F2=F2" made a long, widespread and gnarly stand against his pathological enlightenments.

Goldencirclewithgoldenpyramidinside.jpg


Only when we accede to grasping the Golden ISO Exposure Pyramid can we truly understand.

:P
 
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