[Kunzite]

No problem. I only use true equivalence.

---------- Post added 06-12-14 at 03:09 PM ----------



It is both true and applicable outside of comparisons of DOF.

Equivalence is a lie. The only thing that's true is physics, and even that's uncertain after a certain level.

[jsherman999]

Equivalence is a lie. The only thing that's true is physics, and even that's uncertain after a certain level.

It is absolutely not a lie, and in fact is completely and utterly based on physics. (And here I thought you had been making progress. )

And by the way, you never answered my question from that other thread! Let's say you heard someone say this, how would you respond, without sidestepping or weaseling?

"I don't know what's so great about your 77mm f/1.8 Limited - I have a 75mm f/1.8 for my Olympus m/43, same FL and just as fast, so it gives me the same shutter speed and noise performance on my camera."


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[Parallax]

It is absolutely not a lie, and in fact is completely and utterly based on physics.

That's absolutely correct.
That's why FF lets people produce those highly coveted one eye in focus portraits.

[jsherman999]

That's absolutely correct.
That's why FF lets people produce those highly coveted one eye in focus portraits.

(*&(^&^$@)(&^&%^$^%$^& !!!

Here, just for you I got the whole face in focus:




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[cali92rs]

That's absolutely correct.
That's why FF lets people produce those highly coveted one eye in focus portraits.

Same ol' nonsense...
It's amazing that all those pros with FF cameras can even stay in business when their cameras are only capable of 1" depth of field shots.
You better inform all those guys that shoot D800 and 645s for landscapes that their cameras are incapable of achieving adequate DOF.

*psssst...here's a helpful tip and a secret i have learned over the years...you can actually make the aperture on your lens smaller by turning a ring, or dial and in turn, obtain greater depth of field...and even Full Frame, Medium Format AND Large Format cameras can do this.....shhhh...don't tell anyone*

[Kunzite]

It is absolutely not a lie, and in fact is completely and utterly based on physics. (And here I thought you had been making progress. )

And by the way, you never answered my question from that other thread! Let's say you heard someone say this, how would you respond, without sidestepping or weaseling?

"I don't know what's so great about your 77mm f/1.8 Limited - I have a 75mm f/1.8 for my Olympus m/43, same FL and just as fast, so it gives me the same shutter speed and noise performance on my camera."
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Funny. We started from a complete and utterly defiance of basic optics, i.e. the claim that focal length changes at one's whims.

I have to ask you again to read Joseph James' article, and pay attention to the part where he's explicitly excluding noise from the list of "equivalence" parameters. The idea that the lens is "giving" you noise is another lie, fortunately not all equivalentionists agree.

[jsherman999]

Funny. We started from a complete and utterly defiance of basic optics, i.e. the claim that focal length changes at one's whims.

I have to ask you again to read Joseph James' article, and pay attention to the part where he's explicitly excluding noise from the list of "equivalence" parameters. The idea that the lens is "giving" you noise is another lie, fortunately not all equivalentionists agree.

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I'm pretty sure I'm the one who introduced you to that article, although you'll never admit that.

Serious question: how do you reconcile your saying "equivalence is a lie" in one post and "read Joseph James' article" in the subsequent post? Pigeon chess?

By the way, your "equivalence doesn't apply to noise" comment tells me you still haven't really understood the article. I'll paste my earlier response, please read carefully:

Yes, I know. Equivalence cannot encompass noise as a parameter, because too much is dependent on read noise (vs. photon shot noise) and sensor efficiency. However, a direct application of equivalence is assessing what kit to put together to minimize noise while keeping sensor efficiency in mind. Joseph James himself uses it this way, and has explained scenarios in those terms to people in forums.

For example, given sensors of roughly equal efficiency (same gen) as measured by DxOMark or sensorsgen or some similar entity, what combo has the potential to give you less noise?

50mm f/1.8 FF
35mm f/1.4 aps-c
25mm f/0.95 m43

You can't use equivalence alone to answer that, (unless you just go with a very theoretical answer based on "sensors of equal efficiency",) However you can apply equivalence in combination with the externally-sourced data to come to a pretty accurate conclusion.

In other words, image noise is dependent on A) Total Amount of Light Falling on the sensor and B) the sensor efficiency. Equivalence helps you determine A.


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[Parallax]

(*&(^&^$@)(&^&%^$^%$^& !!!

Here, just for you I got the whole face in focus:

[Kunzite]

I'm not in the mood of going through another "equivalence" discussion with you, knowing that it's pointless of doing so. I will only say this: all forms of "equivalence" are lying about something. Perhaps they're lying about what focal length is, or maybe just about using a set of 5 parameters to compare between formats.

[normhead]

I'm looking in my optical physics text book for equivalence, I don't see it, what page is it on? Please don't give me a link to some crazy photographer, making up stuff, I'd like something by a physicist. The laws of optical physics have been invoked one to many times for my liking. Photographers may or may not know what they are talking about, a nice quote from an optical physics text book would be excellent, and would probably clear up a lot of confusion.


....


I'm waiting.

[jsherman999]

I'm looking in my optical physics text book for equivalence, I don't see it, .

Norm you have a textbook on "optical physics!"? Let's see a shot of the cover.

Anyway, you could refer to Falk Lumo who you know, or Bob Newman who runs sensorsgen - they've both written about equivalence. Joseph Wisniewski (who used to shoot Pentax) is an engineer/scientist who claims he was teaching equivalence between formats before there was a term for it, back in the 80s and 90s. Eric Fossum, who invented the CMOS sensor, has talked about read noise in an equivalence discussion and fully accepts the tenets of equivalence which to him were self-evident and didn't even require debate. Email any of those guys if you want.

You certainly don't need to be a physicist to understand and accept it, though, just like you don't need to be a physicist to understand and accept f=ma or the theory of gravity. The theory of gravity is actually much less easy to understand but the effects of gravity and equivalence are both there for you to witness yourself.

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[normhead]

Norm you have a textbook on "optical physics!"? Let's see a shot of the cover.

Anyway, you could refer to Falk Lumo who you know, or Bob Newman who runs sensorsgen - they've both written about equivalence. Joseph Wisniewski (who used to shoot Pentax) is an engineer/scientist who claims he was teaching equivalence between formats before there was a term for it, back in the 80s and 90s. Eric Fossum, who invented the CMOS sensor, has talked about read noise in an equivalence discussion and fully accepts the tenets of equivalence which to him were self-evident and didn't even require debate. Email any of those guys if you want.

You certainly don't need to be a physicist to understand and accept it, though, just like you don't need to be a physicist to understand and accept f=ma or the theory of gravity. The theory of gravity is actually much less easy to understand but the effects of gravity and equivalence are both there for you to witness yourself.

.

My source....
Equivalence

And the one thing I got from it is most of the people who talk about equivalence are full of it. I'm actually thankful to this guy. He explains the caveats I've dwelled on for years, that always seem to get ignored. Sorry about the optical physics textbook thing, I sold it when the semester ended. I always though having photographers learn optical physic, that it was just being used as a wash-out course. The guys who weren't smart enough to understand it wouldn't get their diplomas and qualify as graduates, whether they were good photographers or not.

So I'll just post the Q and A

Q: Are bigger formats better than smaller formats?

A: For some specific purposes, yes; for others, no. The more specific the purpose the of photography, the easier it becomes to say that System A is "better than" System B for a particular photographer; the more broad the photography, the less easy it is for one system to be superior to the other.



Q: When are larger formats better than smaller formats?

A: To answer this question, we need to invoke the "all else equal" clause, because there are so many variables that may make one system better than another for any particular photographer. In short, the advantage of a larger sensor system over a smaller sensor system is that the larger sensor system will generally have lenses that have wider aperture (entrance pupil) diameters for a AOV (diagonal angle of view) than smaller sensor systems, which allows for more shallow DOFs (as an option, not a requirement) and will put more light on the sensor for a given exposure, resulting in less noise. In addition, larger sensors typically have more pixels which, when combined with a lesser enlargement factor from the recorded photo to the displayed photo, results in more detailed photos (at least for a given DOF). Whether or not these advantages are more important than the disadvantages (size, weight, cost, etc.) is another matter all together.



Q: Isn't Equivalence a vehicle for promoting the "superiority" of larger sensor systems?

A: Not by a long shot. If there is an agenda to Equivalence, it is to change the photographic paradigm based on the relative aperture (f-ratio) and exposure with a new paradigm based on the virtual aperture (entrance pupil) and total amount of light falling on the sensor, at least for cross-format comparisons.



Q: So Equivalence is about the lens as opposed to the sensor?

A: That's a good way to put it -- it's the virtual aperture (entrance pupil) for a given AOV that is of central importance. However, sensor size still plays a role, as larger sensors typically have more pixels and typically can absorb more light for a given exposure.



Q: Isn't Equivalence all about DOF?

A: No, Equivalence is not "all about DOF", but it is very much about understanding that both DOF and noise are intimately connected to the aperture. That said, DOF, by itself, is still a critical consideration to the captured detail in the photo, since portions of the scene outside the DOF, by definition, will not be sharp, and all systems suffer diffraction softening equally at the same DOF.



Q: Doesn't Equivalence say that we should shoot different formats at the same DOF?

A: Not at all, and, in fact, quite the opposite. That is, one does not choose one format over another to get photos Equivalent to what one would get on another format. Rather, one chooses one format over another to get photos they could not get on another format, or get better photos than they could get on another format, assuming, of course, that differences in operation, size, weight, and cost are not significant enough to be the primary consideration.



Q: Overall, then, isn't FF best the choice?

A: Again, which is best is completely subjective. While for me, personally, I prefer FF, it is my opinion that the vast majority are better served with smaller formats. As all systems continue to improve, the number of situations where FF has a significant advantage over smaller formats narrows. Of course, if size, weight, and price were not considerations, then larger is almost always better. However, since size, weight, and price not only matter, but are often (usually) the primary considerations, then it is my opinion that the advantages of FF over smaller formats are not enough to offset the disadvantages for most people in most situations.

Based on the bold part, if al else isn't equal, all bets are off, and that is the weakness of equivalence as it is used to champion FF on this forum. "All else" is never equal. And therefore all arguments are meaningless, unless the formula used has been altered to take into account the differences, which I have never even once seen.

I hope folks will read this over, until they understand why equivalence cannot be applied to generally describe the difference between specific systems and lenses and make broad general statements about different systems. You can only use Equivalence on the forum, to describe a specific situation where all things are equal, with different sensors, different lens designs, etc. there are so many crucial variables, that it's pretty safe to say, not one person on this forum who claims to propose to understand equivalence has ever posted accurate information relevant to the systems being discussed. Only theoretical postulates based on non-existent criteria, assumed for convenience, not for accuracy.

I think optical physics is on mysids on this one.

[OregonJim]

(from Norm's quote):

In short, the advantage of a larger sensor system over a smaller sensor system is that the larger sensor system will generally have lenses that have wider aperture (entrance pupil) diameters for a AOV (diagonal angle of view) than smaller sensor systems, which allows for more shallow DOFs (as an option, not a requirement) and will put more light on the sensor for a given exposure, resulting in less noise

So, all of my lenses are designed for a FF (35mm) system. I use them on my K-3. Therefore, the whole equivalence argument goes out the window, because the advantage is all in the FF lenses, according to the FF proponents. But I'm already using the SAME LENSES, so I get all the 'equivalence' advantages on my APS-C sized sensor. Don't you guys see the folly in the whole theory?

[normhead]

(from Norm's quote):



So, all of my lenses are designed for a FF (35mm) system. I use them on my K-3. Therefore, the whole equivalence argument goes out the window, because the advantage is all in the FF lenses, according to the FF proponents. But I'm already using the SAME LENSES, so I get all the 'equivalence' advantages on my APS-C sized sensor. Don't you guys see the folly in the whole theory?

Except where you're capturing half the light because your sensor is half the size and you have to blow your image up to twice the size to get the same sized image, if I learned one thing reading through this stuff, it would be, it's so complicated, no one really wants to do the math, except for the most simplistic examples. Which is what gets posted on the forum. If you go through and look at all the factors and formula that go into it, to me, it's better to just leave it alone. Accept the general principles and also except that there are reasons why your results with real life systems may differ.

[redrockcoulee]

Norm you have a textbook on "optical physics!"? Let's see a shot of the cover.

Anyway, you could refer to Falk Lumo who you know, or Bob Newman who runs sensorsgen - they've both written about equivalence. Joseph Wisniewski (who used to shoot Pentax) is an engineer/scientist who claims he was teaching equivalence between formats before there was a term for it, back in the 80s and 90s. Eric Fossum, who invented the CMOS sensor, has talked about read noise in an equivalence discussion and fully accepts the tenets of equivalence which to him were self-evident and didn't even require debate. Email any of those guys if you want.

You certainly don't need to be a physicist to understand and accept it, though, just like you don't need to be a physicist to understand and accept f=ma or the theory of gravity. The theory of gravity is actually much less easy to understand but the effects of gravity and equivalence are both there for you to witness yourself.

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So is lens equivalency strickly a digital thing and not applicable to film cameras?