[jsherman999]

Wrong; that's a personal opinion, and if there is a pseudo-religious view regarding this matter it belongs to you.

What, precisely is 'pseudo-religious' about equivalence? It simply describes a physical relationship. Do find something about it factually incorrect?

Physical facts are things like focal length, which was claimed to be a lie. Logical facts are things like "equivalence" breaking apart if you use the same lens on multiple formats, and if you crop.

How on earth does equivalence 'break apart' when you use the same lens on multiple formats? One of the best applications of equivalence is in determining how a lens will perform on multiple formats. And the effects of cropping is well defined and doesn't deviate from what equivalence tells us in any way.

I'm wondering how much you're really talking about equivalence now and how much you're talking about Tony's specific assertion that manufacturers should write the equivalent FL and F-stop on the lens. If you don't agree with writing it on there that's fine (I might agree,) it doesn't make the underlying equivalence relationship between any two formats just magically go away if you can't see it on the lens.

Wrong. I learned the new format by using it.

And before ou put that 50mm lens on your aps-c body did you expect it to have the same FOV as it did on your film body? No? That's good, that means you used equivalence to convert the effective FOV in your mind beforehand.

You don't have to go any further if it doesn't matter to you - you can pretend the F-stops all look the same too - but you can't assert you'd be correct in any way, you can only assert that "it doesn't matter to me". It might matter quite a bit to someone else.

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Last edited by jsherman999; 05-20-2014 at 12:42 PM.

[virgilr]

Correct me if I'm wrong - but if I take a photograph with 35mm film and I crop out an equivalent aps-c region, do DOF and OoF blur change in the area that is cropped? I don't think so... so if a sensor captures a portion of the lens image circle the effect is the same right? Or maybe I'm wrong. To me the only factor that should be considered when using the same lens on different sensor formats is the FOV. The optical characteristics on the image rendered are a function of the lens not the sensor. Maybe I'm wrong again...

[Winder]

Correct me if I'm wrong - but if I take a photograph with 35mm film and I crop out an equivalent aps-c region, do DOF and OoF blur change in the area that is cropped? I don't think so... so if a sensor captures a portion of the lens image circle the effect is the same right? Or maybe I'm wrong. To me the only factor that should be considered when using the same lens on different sensor formats is the FOV. The optical characteristics on the image rendered are a function of the lens not the sensor. Maybe I'm wrong again...

Let's assume we are printing for A3+, so I have to equalize for final output.

A3+ is 158,907mm^2
D800E sensor size is 864mm^2
K-5IIs sensor size is 370mm^2

To print at A3+ the image from a D800E has to be enlarged 183 times.
To print at A3+ the image from a K-5IIs has to be enlarged 430 times.

The FF sensor has 2.3 x more surface area to collect light.

As you magnify the image you change the appearance of the out of focus areas and the DoF. Ever looked at a small image and think it is in focus, but when you go larger to edit it you see that is is actually not in focus? This part of the compression effect that you get from magnification.

[Kunzite]

What, precisely is 'pseudo-religious' about equivalence? It simply describes a physical relationship. Do find something about it factually incorrect?

You tell me; you were the one talking about the Catholic Church.

What's wrong is the way you've built this "equivalence", a rigid, no-matter-what system comprising 3 parameters whose meanings were twisted beyond recognition. "Focal length" as a measure of angle of view; "aperture" as a measure of Dof and "ISO" as a guess of noise levels.
I don't have any problem comparing what I want, between whatever formats (including different aspect ratios) using the real notions - which are playing nice and are consistent.

How on earth does equivalence 'break apart' when you use the same lens on multiple formats? One of the best applications of equivalence is in determining how a lens will perform on multiple formats. And the effects of cropping is well defined and doesn't deviate from what equivalence tells us in any way.

Have you figured it out then, what should be written on a lens used on multiple formats?

The effect of cropping is the same as using a different format; same if cutting a print with a pair of scissors.

I'm wondering how much you're really talking about equivalence now and how much you're talking about Tony's specific assertion that manufacturers should write the equivalent FL and F-stop on the lens. If you don't agree with writing it on there that's fine (I might agree,) it doesn't make the underlying equivalence relationship between any two formats just magically go away if you can't see it on the lens.

Both. Something so fragile that would break apart just by post processing your images is said to be better than the focal length. Not being able to write "equivalent" numbers of the lenses simply illustrates the problem. Blaming the manufacturers for using real values is laughable.

And before ou put that 50mm lens on your aps-c body did you expect it to have the same FOV as it did on your film body? No? That's good, that means you used equivalence to convert the effective FOV in your mind beforehand.

Actually I looked through the viewfinder. It made no sense to me to say it would be "equivalent to a 75mm" as I didn't had a 75mm handy.

<sarcasm>No, I had to wait for you people to invent "equivalence" to realize it. Because the relation between focal length, format and angle of view is not written in every d*mn photography book. </sarcasm>

You don't have to go any further if it doesn't matter to you - you can pretend the F-stops all look the same too - but you can't assert you'd be correct in any way, you can only assert that "it doesn't matter to me". It might matter quite a bit to someone else.

Great, first the pseudo-religious stuff and now the "silly strawmen" strategy. What's next?

[TRex1123]

Kunzite, I am seeing your point a little bit here but I am confused. Am I correct in saying that you are simply using the tools (lens, camera, and your eye) to create an image; no more, no less? Focal length, Aperture, and ISO are just arbitrary numbers? Almost Dionysian, if you will.

If my comprehension is correct my next question would be when someone asks you to recreate an image or asks how its done what do you tell them?

I am not being sarcastic, I am genuinely curious.

[Kunzite]

Absolutely not; don't mix precisely defined terms like focal length, aperture and ISO with "equivalence". I'm only arguing against the latter, and it would be silly to do otherwise.
It's actually the video saying that "camera settings are kind of arbitrary and meaningless"; I called that an EPIC FAIL.

Is this about jsherman999 attempts at convincing himself that I used "equivalence" to convert from a lens+camera that I had in my hands to one that I never had/used?
It's not like looking through the viewfinder would erase from my mind all the basic notions... If needed, I can indeed "recreate an image" by using the good, old ways where focal length is an optical property and can't be changed on a whim. I can also compare whatever characteristic I want between two formats, though I wouldn't go too far into paper benchmarking. Thus, "equivalence" is unneeded.

[Winder]

It's actually the video saying that "camera settings are kind of arbitrary and meaningless"; I called that an EPIC FAIL.

Is this about jsherman999 attempts at convincing himself that I used "equivalence" to convert from a lens+camera that I had in my hands to one that I never had/used?

ISO has become meaningless in some ways. It doesn't mean what it use to mean. In the film days 400 ASA/ISO Tri-X would yield the same results regardless of the camera you put it in. Today 400 ISO could yield very different results depending on the camera you are using because different manufacturers are applying different amounts of amplification, using different technology, and processing the files differently.

The world doesn't evolve around your past experiences. There are people who will buy into one system (APS-C) and then move to another system. Just because you only use one format and have no need to use equivalence don't mean that other people who watch the video don't find value in it.

You may not care about focal length conversion. His point is that manufacturers advertise the equivalence and do so in a way that is sometimes misleading. You finding value in that is irrelevant to his point and just because you don't find value in it doesn't make it a "FAIL".

You might want to sit down for this...... The world doesn't revolve around you.

[Rondec]

Equivalence ends up leading to more confusion when people only partially understand it. A 135mm lens is a 135mm lens regardless of the format/crop. Yet, there are people who are convinced that the DA/DX lenses are the right focal length on their camera, while lens like the FA lenses are a different focal length on APS-C.

Equivalence is only useful when someone is familiar with full frame (most people aren't at this point). My point of view is APS-C and so if I am shooting with a new format, I would prefer to have equivalence in APS-C terms, not mythical 35mm terms that I haven't shot in 10 years.

[TRex1123]

So that brings up the question is there a "Standard" that should be used for all photography? Or do we need to look at specific sensor size for each category? It is apparent that Focal Length, Aperture, and ISO yield different results on each sensor. Although, both the video and everyone in this thread agrees that ISO is basically antiquated.

What should the "standard" be? or should there be one? The general public feeds off of these equivalencies and MUST have them before they purchase anything. This whole conversation reminds me of the "Contrast Ratio" debate that plasma and LCD televisions had in the early 2000's.

[Kunzite]

In the film days 400 ASA/ISO Tri-X would yield the same results regardless of the camera you put it in.

Why are you talking about a specific emulsion? The only thing you would know by sticking to ISO400 is that the same exposure would work. Relatively speaking, as even with film you could e.g. push-process the film...
That it's not exactly the same, I agree; but going as far as claiming it's meaningless? And how about focal length, which is a basic property of an optical lens? Is it "kinda meaningless" as well?

The world doesn't evolve around your past experiences. There are people who will buy into one system (APS-C) and then move to another system. Just because you only use one format and have no need to use equivalence don't mean that other people who watch the video don't find value in it.

You may not care about focal length conversion. His point is that manufacturers advertise the equivalence and do so in a way that is sometimes misleading. You finding value in that is irrelevant to his point and just because you don't find value in it doesn't make it a "FAIL".

Do you have an issue with me using past experience to give examples that don't require "equivalence" (despite what people here claimed)? Do you perhaps believe that everything that doesn't support "equivalence" should be silenced?

Manufacturers don't advertise "equivalence", but merely "equivalent to FL on 35mm"; I don't see any claims that DoF and noise being the "same".

People moving between systems might want to compare specific things, instead of using "equivalence". Perhaps they are moving because the new system offers something different.

You might want to sit down for this...... The world doesn't revolve around you.

The world doesn't revolve around "equivalence", nor around people supporting it.

So that brings up the question is there a "Standard" that should be used for all photography? Or do we need to look at specific sensor size for each category? It is apparent that Focal Length, Aperture, and ISO yield different results on each sensor. Although, both the video and everyone in this thread agrees that ISO is basically antiquated.

If we stick to what focal length, aperture and ISO are, they yield precisely the expected results on any format. The video falsely burden those notions with additional meaning, then falsely claiming they can't cope with that thus are "kind of arbitrary and meaningless".
Since ISO is one of the 3 parameters determining the exposure, it's far from antiquated. Unless you found a way to take pictures without exposing a sensitive surface to light.

[TRex1123]

If we stick to what focal length, aperture and ISO are, they yield precisely the expected results on any format. The video falsely burden those notions with additional meaning, then falsely claiming they can't cope with that thus are "kind of arbitrary and meaningless".
Since ISO is one of the 3 parameters determining the exposure, it's far from antiquated. Unless you found a way to take pictures without exposing a sensitive surface to light.

But you don't yield the same frame taking an image on a FF vs APS-C vs MFT. The sensor essentially crops the frame effectively zooming in on the image, if what I have read is correct. What creates the difference in DOF though?

Whenever I think I am understanding what you are trying to say I confuse myself all over again. So I will type this out.

Focal Length - the distance in millimeters from the optical center of a lens to the imaging sensor when the lens is focused at infinity. I believe this is where most of the confusion comes from. You are saying this is ALWAYS constant regardless of sensor size? Which by definition is correct.

Aperture - a space through which light passes in an optical or photographic instrument, especially the variable opening by which light enters a camera. By definition again, your argument holds up. You can physically measure the space in which light passes.

That's the lens part in which everything is absolutely the same but when you add in the sensor it changes the frame and that is were the confusion really starts.

Depth of field - is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image. Further... The combination of focal length, subject distance, and format size defines magnification at the film / sensor plane. (Depth of field - Wikipedia, the free encyclopedia)

Field of view, I've being referring to this as the frame - In photography, the field of view is that part of the world that is visible through the camera at a particular position and orientation in space; objects outside the FOV when the picture is taken are not recorded in the photograph. It is most often expressed as the angular size of the view cone, as an angle of view. For normal lens, field of view can be calculated FOV = 2 arctan(SensorSize/2f), where f is Focal Length. (Field of view - Wikipedia, the free encyclopedia)

Am I at least heading down the correct path now?

[Yassarian]

I'm wondering why this is so hard for people to grasp...

Lets say you have a m43 camera with a 25mm f1.4 lens (both of these numbers describe accurately the physical attribute of the lens), and you take a photo with it, standing 10 meters away.

What kind of lens on a FF camera would you need to have, to be able to roughly take the same shot standing 10 meters away?

You would need a 50mm lens, set to f2.8, to roughly get you the same shot with the same blur characteristics on the full frame.

So is it accurate to say that the m43 lens is a 25mm f1.4 lens? Absolutely! Because these are the true physical attributes of the lens. HOWEVER is it equivalent(i.e., can capture the same picture) to a 50mm f1.4 lens on a FF camera? Absolutely NOT - because it is only equivalent to a 50mm f2.8 lens. This is nothing new, this is what the author is saying, Not sure why this is so hard to grasp...

[audiobomber]

Absolutely not; don't mix precisely defined terms like focal length, aperture and ISO with "equivalence". I'm only arguing against the latter, and it would be silly to do otherwise.

How precise do you think ISO is?

From DXOMark measurements:
Olympus OMD-EM1, measured ISO 122, manufacturer ISO 200
Pentax K-3, measured ISO 189, manufacturer ISO 200

From the DPR test of the Fuji X-T1:
"it's also important to understand that Fujifilm's extremely conservative sensitivity ratings mean that ISO6400 on the X-T1 is closer to ISO4000 on most other cameras."

The video is not about whether the concept of full-frame equivalence should exist. It does exist, whether you like it or not, and it will never go away. The video condemns the misuse of equivalence, especially manufacturers' penchant for stating equivalence in focal length only, and how that is deceiving consumers.

Don't use equivalence if you don't like it, although I believe you are using it and not admitting it. I have no quarrel with saying that a bridge zoom lens is 4.5-108mm f2.8. That is a correct and unassailable statement of fact, no equivalence, no partial equivalence. Claiming the same camera is 24-600mm f2.8 is a mix of equivalence and actual, and factually incorrect. Saying the camera is 28-600mm equivalent FOV, f/2.8, is technically correct, but is misleading.

[Kunzite]

But you don't yield the same frame taking an image on a FF vs APS-C vs MFT. The sensor essentially crops the frame effectively zooming in on the image, if what I have read is correct. What creates the difference in DOF though?

Whenever I think I am understanding what you are trying to say I confuse myself all over again. So I will type this out.
[...]

Indeed, the difference in DoF (and not only) is because of the magnification. You're starting with a smaller part from the same image, and enlarge it more; thus the concept of "what is reasonably sharp" (the circle of confusion) is changing (getting smaller).

You nailed everything; I'm not sure where the confusion is?

I'm wondering why this is so hard for people to grasp...

Apparently, it's very difficult

How precise do you think ISO is?

I'm not making any claims regarding precision. But it would be interesting to test those cameras with a well calibrated lens and using an external meter as a reference.

The video is not about whether the concept of full-frame equivalence should exist. It does exist, whether you like it or not, and it will never go away. The video condemns the misuse of equivalence, especially manufacturers' penchant for stating equivalence in focal length only, and how that is deceiving consumers.

It obviously exist, that's why this discussion.

The video also condemns focal length not getting you the same angle of view on different formats, among other things. That's arguing against physics.

Don't use equivalence if you don't like it, although I believe you are using it and not admitting it. I have no quarrel with saying that a bridge zoom lens is 4.5-108mm f2.8. That is a correct and unassailable statement of fact, no equivalence, no partial equivalence. Claiming the same camera is 24-600mm f2.8 is a mix of equivalence and actual, and factually incorrect. Saying the camera is 28-600mm equivalent FOV, f/2.8, is technically correct, but is misleading.

You're deluding yourself by thinking that I am somehow using "equivalence" without realizing it.

I understand your point about the values not allowing correctly estimating the DoF. I don't think the targeted customers cares about DoF, but they would want to see "how much fits in the picture" and "can it get things closer" without bothering with sensor sizes. Usually they would want everything "sharp", and they would get it.

There is nothing misleading in choosing two lenses with similar FOV yet different other characteristics, if it's clear (or assumed by every party involved) that only FOV is being compared.

[jsherman999]

Equivalence is only useful when someone is familiar with full frame (most people aren't at this point).

It's actually required when you need to convert between any two formats and doesn't need to have anything to do with FF at all.

For example, say you have a P&S with a built-in zoom, and you want to move up to an M43 MILC, but don't want to lose that P&S zoom range, which you really like - how do you select an m43 lens that has the same FL range? You need to use equivalence.

Most people stop there at the FL conversion and don't worry about the F-stop conversion, either because they don't care or they don't know about it. But as I was trying to explain to kunzite, just because you personally don't care or don't know about it doesn't mean it's not real

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---------- Post added 05-21-14 at 12:36 PM ----------

I'm wondering why this is so hard for people to grasp...

Lets say you have a m43 camera with a 25mm f1.4 lens (both of these numbers describe accurately the physical attribute of the lens), and you take a photo with it, standing 10 meters away.

What kind of lens on a FF camera would you need to have, to be able to roughly take the same shot standing 10 meters away?

Kunzite - I challenge you - try to answer the above question without using equivalence.

(if past is any indication I suspect you'll decline, and say something like "don't worry about it, just look through the veiwfinder and accept what you get, like I did, to learn my system.." or some variation.)


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---------- Post added 05-21-14 at 12:48 PM ----------

People moving between systems might want to compare specific things, instead of using "equivalence". Perhaps they are moving because the new system offers something different.

I'm not able to see why this concept is so alien, upsetting and disruptive to you. 'equivalence' just describes the relationship between any two formats. It's USED to 'compare specific things' between systems, that's what it's used for. It's fantastically useful for making purchase decisions if you started with one format and are moving to (or adding) another and have some preferences or settings standards you want to maintain. And it can really help you save money.

Please, if you haven't already, take the time to read through this, or jump straight to this (system comparison.) You'll notice that nowhere in there is he giving preferential treatment to one format.
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