The Difficulty in Explaining Equivalence

I would prefer it to be out in the open too, but as you know the moderator will eject anyone who he perceives is not agreeing that m4/3 is equal or better than FF.

And if you also throw in the fact that a large number of people are viewing images on small screens, the differences are difficult to see.

Thanks, I will have a read of this.

@GreatBustard...

Joe, if I can just side-track the conversation with a question.

In the examples I have used in previous posts (in my debate with the DPR forum member) I use the basic formula to show the physical size of the aperture for a prime lens, e.g. 50mm focal length ÷ f/2.8 = 18mm aperture.

Now... say we have a zoom lens 24-105mm f/4. This means at 24mm the aperture would be 24 ÷ f/4 = 6mm and at 105mm it would be 105 ÷ f/4 = 26mm. Which means that the physical aperture gets wider the further you zoom. Is that right? And therefore total light is higher at longer focal lengths? And DOF more shallow?

When I think of constant aperture zoom lenses like the 24-105 f/4, the assumption I've always made is that the aperture doesn't change at any focal length, but this must only be true in terms of the f-ratio but not true in terms of the actual physical aperture.

Or have I got something wrong here? 😟

Even if the physical aperture doesn't change, something has to change in a constant aperture zoom lens. It might only be an 'apparent' change, but the resulting effects are the same..

In a constant aperture zoom scenario, total light is the same at all focal lengths (aside from things like corner falloff) ... but yes, DOF naturally gets more shallow as the focal length increases..

HAND.

I just read the ctein article and the comments. OMG. 😂

Why does it seem to be mostly Olympus m4/3 owners who deny equivalence? Is the Olympus marketing that powerful?

OK, so I am not understanding the part about total light being the same at all focal lengths.

Why would it change? The f-number (f/4 in this case) is still the same, and the sensor area is still the same, so total light is still the same, just as if you mounted any prime and shot photos at f/4.

It is as finnan posted:

In short, the effective aperture (entrance pupil) is what's relevant with regards to both DOF and the total amount of light projected on the sensor whereas the relative aperture (f-number) is what's relevant with regards to exposure (the density of light projected on the sensor).

Oh, one more thing: ISO. The ISO setting has little to do with noise except as it indirectly affects the exposure settings on the camera (f-number and exposure time). That is, if you raise the ISO setting from 400 to 1600, then the camera will choose a combination of f-number and/or exposure time that is two stops different, and it is that which results in the greater noise in the photo, not the higher ISO setting, per se. Interestingly, if we keep the exposure the same (e.g. using M mode), then higher ISO settings are less noisy than lower ISO settings, but how much less can vary quite a bit depending on the sensor in the camera and the particular ISO settings used.

its just the price of older m43 cameras and the spec sheet made them attractive . but as time moves on (5 years) FF is so far ahead now in every department. even with my em12 shooting pro studio work af was that inconsistant I shoot at f7.1. now i own the a7iv i can shoot 100% acuracy at f3.2 and that includes full body portraits. but you still see guys shooting studio at f8.

Fear not -- if a certain person wins the Presidential election here in the US, we will see the US withdraw from NATO and give Putin free reign to spread peace in Europe, and the US will become a paradise for White Supremacist Christofascists that the whole world will look up to in awe and wonder as we set the example for the world, once again. You're welcome! 😁

So the calcs that I posted are correct? i.e.
- 24mm ÷ f/4 = 6mm
- 105mm ÷ f/4 = 26mm
which means that the effective aperture gets wider as you zoom.

Thanks, that makes sense.

I guess the point I was making is that many Olympus users truly believe their cameras are supreme over all else, despite facts showing they are not.

the problem was DPR shooting a test scene that was not a chalenge for any camera and a very poor test scene for very advanced cameras of today. i was one of the biggest advocates for shooting m43 back in the day,( ask GB) but all i was posting was my skill not the cameras abillity. how many people were worshiping m43 with shooing the best macro images as the camera had a larger DOF. it wasnt till i switched to the sony a7r2 and even my a6300 that my macro images were on another planet. i was shooting some great extreme macro as well bacj 5 years , but its only been recently that ive taken even extreme macro to a new level including equipment design thats so much more advanced than anyone else is shooting today. ive been in a private conversation with one of the old mods thats just strting shooing extreme macro and i posted him a image of my setup which i havent to anyone in the past just to show him how simple and advanced my set up is compared to all the utubers. i havent heard back yet, he is probally thinking wow thats amazing why have i spent so much money copying other systems.

Yep!

And there's the key thing to explain. It's important to understanding why these different effective apertures result in the same exposure [for a given format]. I mean, if the aperture diameter is wider, more light should get through, and the exposure should be much greater, right? The reason the wider aperture results in the same exposure can be understood in two ways.

In one scenario, imagine that we are standing 105 / 24 = 4.375x further back from the subject. This means that the intensity of the light reaching us is 1/4.375² = 5.22% as bright, because it has spread out over 4.375² = 19x the area. But the effective aperture at 105mm f/4 (26mm diameter) has 19x the area as the effective aperture at 24mm f/4 (6mm diameter), so the the resulting intensity of light projected on the sensor is the same.

In another scenario, imagine we are standing in the same position. In this case, 24mm is seeing 19x as much area of the scene as 105mm, thus, assuming the same average scene luminance, projecting 19x more light on the sensor. However, the effective aperture area at 105mm is 19x greater, which also projects 19x more light on the sensor. So, the two effects cancel each other out, and, again, we have the same total amount of light projected on the sensor, thus the same exposure (for a given sensor).

In other words, simply saying the aperture area is larger isn't convincing unless one understands the why behind it. The problem with the anti-Equivalence crowd is that they have no interest, whatsoever, in understanding. They worship the "exposure god", without having any understanding of what exposure really is, how it relates to any of the three apertures or total light, and how any of that connects with DOF and/or noise.

I mean, it's fine if they don't care. What irks me is how they argue against the facts Dunning-Kruger style, proudly putting their willful ignorance on full display to the cheers of those with like "minds". Once, a long while back, one of these willfully ignorant people said, "I don't even care that they're right -- their arrogance is so condescending and off-putting." An attitude shared, no doubt, by TC, jalywol, etc.. And yet, these same people are so self-unaware to realize that the arrogance and condescension comes from their Dunning-Kruger style of "discussion", their insults and snide remarks, their willful ignorance, that predicated the frustration on our part. As I linked and quoted here, beginning my being sandboxed:

The Editor-in-Chief of DPR at the time, Simon Joinson, put it like this:

Firstly, most of these 'troll threads' that I've seen are started by people who refuse to accept simple scientific facts, and who get aggressive when their faulty reasoning is challenged. It's not trolling to respond (as i did) to threads started to suggest that my writers are wrong about equivalent aperture by pointing to the actual science that proves they've misunderstood.

...

These threads often get more posts (and even more argumentative) when they're moved to the PST forum because misinformed users start arguing with industry experts (who then complain about all this flat earth stuff appearing in their forum).

which, of course, is all together different than how "they" characterize the matter.

It's absolutely fine to think that your camera/system is best for you. I mean, each person has their own subjective needs/wants, right? So, for someone to think that mFT suits them better than anything else is entirely reasonable. It's when the facts are misrepresented that we have problems. For example, I quoted where jalywol said:

And, don't be fooled by equivalence pretzel logic. If you are shooting the PL 50-200mm at f4 at 200mm, and trying to keep the shutter speed up to capture some fast action, you are going to have a much easier time of it than trying to use the Canon at 400mm at f8. Yeah, sensor noise is going be be different in the FF vs M43, but an f8 lens is not an f4 lens, no matter how you dance on the head of a pin.

and replied:

How is shooting, say, 200mm f/4 1/1000 ISO 400 on mFT "much easier" than shooting 400mm f/8 1/1000 ISO 1600 on FF? The statement you made is not an "alternative viewpoint" -- it's a gross misrepresentation of Equivalence.

I mean, if jalywol simply said that she liked the mFT combo better, and gave the reasons for it, all would be fine. But she just made crap up based on her bias and/or lack of understanding (which, I can comfortably say, since when I asked her, she refused to answer, because, of course, she couldn't).

So, again, thinking mFT is best is not only fine, but absolutely true for many people. But you don't have to be at odds with the facts to hold that opinion.

We need to go back in time to the time when Olympus finally put a viewfinder on a M43 camera and came out with 5 axis IBIS. The EM5 and the follow on EM1 were quite revolutionary for the time (2014) and most of us were using APC cameras, as FF was still very expensive. I could truly take nice sharp pictures of things and places that were impossible with my old D300. As a bonus my EM5 with the Panasonic 12-35 was a whole lot smaller and lighter than my D300 with 17-55 2.8-

I soon found out that I had taken a small hit on the tonal transitioning, but it did not seem too important. The noise difference between the older D300 sensor and the Olympus sensor was not too apparent.

So the M43 forum and maybe MU34 became a club for those who had discovered a revolutionary camera system that let a small lightweight system do stuff we could not do before. Olympus did not need to do much marketing.

So when sombody came along and said "hey guys, you know you are taking a two stop hit on noise and aperture compared to FF when the settings are the same", it is easy to understand that this did not go down too well, with those of us who had been "knocked out" by this system. It is just human nature.

Times change first Sony and then the others came along with mirrorless FF with IBIS too. I bought a Z7 that could do things my EM5 did, with a vast improvement in image quality, as the loss of DoF is mostly irrelevant for me and the probable two stop noise improvement is noticeable and useful. I can do things with my Z7 files in post that were impossible with M43. But the problem is that we need to find out this for ourselves, with two camera systems in hand. Otherwise we are just reading more or less convincing arguments in a debate. Ctein, the main guy in my link is a guy with a long experience in photography, and was a top expert in Dye Transfer printing. He seems to have a scientific background and a big ego. Here is his CV. I believe he is mostly wrong about equivalence in that link, but only because I have compared two camera systems for myself.

So cut some slack for those who are in denial about the question, they are in the company of people with science degrees, it is human nature to defend our spending choices. Sure some of the fans of the system like any other system are pretty ignorant about the technical aspects of photography. Your PM protagonist, is pretty well pleased with what his gear produces, and the problem is that he has not explored the possibilities that a larger sensor offers, and the advantages and disadvantages between M43 and FF.

On my last visit to the UK, I went on a walk with my brother in the countryside near our childhood home. I have a Z7 and he has an OM10. we never once got into an argument about gear, we both just took some good pictures, that looked fine on our screens. A lesson perhaps?

definatley nothing wrong with the product back then. and they were the first camera to stream live via hdmi to my monitors, so sales was up 30% just due to that feature alone.