Debunking the Myth of Full Frame Superiority Part 2

If you are here to understand (why) equivalence (is wrong) then read this:

This article is a continuation of my previous post that stirred multiple different forums. I suggest that you read it first before going through this article. Here’s the controversial post:

Anyway, in an unrelated forum post, a dpreview article was quoted about the benefits of a certain Sigma lens. The quote went like this:

“Sigma’s choice of F1.8 as maximum aperture isn’t a coincidence; it means that the lens will offer the same control over depth of field as an F2.8 zoom does on full frame. What’s more, it will also offer effectively the same light-gathering capability as an F2.8 lens on full frame. By this we mean that it will be able to project an image that’s just over twice as bright onto a sensor that’s slightly less than half the area, meaning the same total amount of light is used to capture the image. This is important as it’s a major determinant of image quality. Essentially it means that APS-C shooters will be able to use lower ISOs when shooting wide open in low light and get similar levels of image noise, substantially negating one of the key advantages of switching to full frame.

Dpreview may be experts in reviewing photographic gear but it looks like they know nothing about photography itself. That article is completely WRONG. A f-stop is a f-stop. Period. Full stop! A f/2.8 lens will always let through lesser light compared to f/1.8 REGARDLESS of format, be it full frame or APS-C or m43.

I found another very very simple proof: FILM!!!

Yes, you read that right. FILM.

Back when the word “photographer” actually meant something, people shot on film. What’s interesting to note is that a particular film emulsion is often made available for different formats. The famous Kodak Ektar 100 for example is available in either (the measly) 35mm “full frame”, in the much larger 120 medium format and even in ginormous 8×10 sheets! The sizes may be different but the emulsion remained constant.

Those who are interested can check out the data sheet for Ektar here:

Here’s the datasheet for Fuji Velvia:

Same emulsion, same response, same everything except size!

If indeed, a larger sensor has more light gathering capability compared to smaller sensors then the same film in different film sizes would need to have different emulsions right? If the myth is true then larger films will have to be less sensitive or they will overexpose. Those shooting with 8×10 view cameras will be overexposing their shots if they follow the same data sheet for 35mm film! We know that’s not true. The same sunny f/16 rule applies to 35mm, 120 or 8×10. The same emulsion behaves exactly the same whether it’s 35mm or 120 or 8×10.

There are some panoramic cameras that allow you to shoot in square format as well just by inserting a mask that blocks the sides of the film. You get to use the same film and lens. Now the shooting instructions don’t change. You still expose the film as if you were shooting a panoramic format. If equivalence was even remotely valid then you would have to change your f-stop and/or shutter speed but you don’t. Same lens, same film, same f-stop and shutter speed even if the film size has changed. Film size does not matter!

Plain and simple! Myth has been truly busted the second time!


15 thoughts on “Debunking the Myth of Full Frame Superiority Part 2”

  1. If I understand correctly you are trying to debunk the statement that when capturing the same image with the same prime lens, the ‘same total amount of light’ is approximately captured by an APS-C sensor at f/1.8 and an FF sensor at f/2.8.

    Referring back to the diagram I linked to in an earlier post you can calculate that if exposure time, Luminance and other variables are held constant the FF sensor will receive (1.8/2.8)^2 fewer photons/mm^2 (or light intensity if you prefer) than the APS-C’s, which however will be compensated by the fact that such lower intensity is collected over the larger area of the FF sensor – approximately (1.6)^2 larger (i.e.Canon).

    The result is that the total number of photons (or light) collected in both the APS-C and FF in such a situation is roughly the same.


    1. Mate, you are still thinking that a camera sensor is like a solar panel where total collected light is everything. That is not how photographic exposure works. I don’t know how to explain to you further so let’s do it this way: You continue believing the myth. It will not affect the shots you take anyway because your myth does not change the physics behind photography.

  2. Hi Mateo, I understand this stuff better than most, so if I am confused by your post you can imagine the rest.

    A number of people have tried to point out why what you say in your ‘debunking’ posts is unclear at best and misleading at worst. I believe the reason for this is that you appear to pick and choose equivalent and non-equivalent situations in either the analog or digital domain depending on the example you are working on without specifying all of the necessary variables – of which there are unfortunately many. This makes it very difficult to have a meaningful discussion.

    For instance your film proof is inconclusive.because you introduce yet another variable – Sensitivity and how manufacturers determine what constitutes ISO 100.- without explicitly dealing with it.

    So if you are interested in exploring how a camera format affects IQ I suggest that you break it down into a number of simple, short and carefully circumstanced blog entries. That’s how Joseph James’ page that was linked earlier started out. And you’ve seen how large it has grown. This stuff is not easy to synthesize.


    1. I did not introduce another variable in my film example. In fact film is PROOF that size does not matter because the SAME FILM having the SAME EMULSION therefore the SAME SENSITIVITY (ISO) has exactly the SAME DATASHEET for DIFFERENT FORMATS.

      People just choose to be really really blind and Joseph James is an idiot. He does not understand f-stop at all. He totally ignores the effect of focal length on light intensity.

      As I have said before, please continue believing what you believe. It won’t change photography. It will save you money though once you realise that you are spending three times more for exactly the same camera LOL!

    2. Speaking of Joseph James, I may have to write a dedicated article for him just like what I did with Ken Rockwell 🙂

      Allow me to show you what kind of an idiot he is. This is taken from his essay:

      “Because Equivalent photos result in a lower exposure for larger sensors (same total amount of light distributed over a larger sensor area results in a lower density of light on the sensor), we typically increase the ISO setting on the camera with the larger sensor to achieve the same brightness as the equivalent photo from the camera with the smaller sensor. A common misunderstanding is that higher ISO settings are the cause of more noise, but this puts the cart before the horse. We use higher ISO settings because less light is falling on the sensor, and it is this lesser amount of light falling on the sensor that results in greater noise, not the higher ISO setting.”

      He actually believes that a full frame will capture lesser amount of light compared to smaller sensors in an equivalent setting. ROFL!!! That’s why he said that a full frame needs to bump the ISO to achieve the same image brightness. Is he on drugs?! My film example totally debunks this. Same film, same emulsion, same ISO works the same way in different sizes!

      Now his supporters think that full frame has superior light gathering when in fact JJ is saying that FF is actually inferior. It’s a circus.

  3. Mateo, I believe you did not read through Mr. James’ page thoroughly and you are confusing the concepts of total photons (light) captured vs Exposure (photons/mm^2 or light density as you called it) and Exposure vs Brightness.

    Equivalence requires that the displayed photograph be as close to identical as possible – independently of the format that captured it. It can only be achieved by the careful choice of a number of parameters which include exposure time, Depth Of Field, perspective and final brightness. To keep DOF and perspective identical in the final displayed photograph ideally the capture needs to be taken by both formats from the exact same location, in manual mode with both f-number and focal length divided by the crop factor.

    However, if the FF sensor’s capture is taken with a larger f-number (smaller aperture) this will result in a smaller Exposure (photons/mm^2***) aotbe. All cameras are designed to record a given Exposure at a certain percentage of their full scales – that’s how a camera’s ISO scale is determined by manufacturers (and the same applies to film). Therefore if Exposure is lower in the FF capture the captured data will show lower values with respect to full scale and therefore appear darker in the final image – unless it is brightened through processing (in-camera or in PP).

    Brightening an image in-camera is done by raising the ISO. So if one wants an Equivakent final photograph it appears that JJ is correct.


    ***The total number of photons (light) in the photograph as captured by both formats remains of course approximately the same because of FF’s larger sensor size.

    1. This equivalency-fu is photographically WRONG. If you want equivalent photos you go

      FF 50mm, f/2.8, 1/60
      APS-C 35mm, f/2, 1/125

      Which gives you same AoV, same DoF, same exposure therefore same image. That’s TRUE equivalence. JJ is insisting on using the same shutter speed so the FF obviously is UNDEREXPOSED at f/2.8 and 1/125. Why would somebody insist on the same shutter speed when the f-stop has changed? Doesn’t he understand reciprocity as well?! So he is ok with different focal lengths and different f-stop to arrive at the same AoV and DoF but he is NOT ok with different shutter speed for the same exposure? He is an idiot.

      You want a true lecture on exposure? Read this:

      Bottomline is, Joseph James does not understand f-stop that’s why he does not understand exposure and consequently exposure reciprocity.

  4. You indicated a way to maintain Exposure approximately constant across formats but which does not result in Equivalent images. As mentioned, images are considered Equivalent when a certain number of physical attributes of the final displayed photograph are held constant. As you say these include AOV (controlled by sensor format and focal length) and DOF (controlled by f-number and focal length) – but also motion blur (controlled by exposure time).

    Clearly a judicious photographer will choose whatever parameters will produce the best compromise to achieve the results she is after on the equipment she has at hand, so Equivalence does not normally enter the equation in the field.

    It is however useful when making buying decisions or comparing different formats for similar applications apples to apples in order to keep the playing field as level as possible. Off the top of my head landscape, sports, indoor low light, birding photography all require different equipment compromises. If one wants to make informed buying decisions Equivalence needs to be applied fully and explicitly lest it result in errors and misunderstandings.


    1. You can consider motion blur but at the cost of exposure reciprocity? ISO is NOT even a part of exposure. It’s all about f-stop and shutter speed. So with your requirement of avoiding motion blur, you have further shown that FF is indeed inferior to smaller sensors because for your equivalency requirement you have to increase ISO to increase shutter speed. FF by all measure then is inferior now that you have enforced extraneous artificial parameters. You have not only confirmed my article but you have practically double-debunked the myth.

  5. This is all manual mode stuff, Mateo. Raising the ISO does nothing to exposure time.

    For the record I am not pushing one format over another: they all have their strengths and weaknesses. Usually the larger format in current implementations provides the photographer with more options in typical photographic situations but smaller formats may be better in specific other ones.

    On the other hand one cannot be successful at debunking myths by picking and choosing data that fits the argument and ignoring data which does not. The debunking needs to stand in more than one undefined situation, especially if buying decisions depend on it. Equivalence may be a caustic approach, but at least it provides a tested framework for creating a level playing field across formats.

    1. Yes, it does nothing to exposure but your guy JJ insists on it just so he could match the shutter speed. And that’s what makes him an idiot.

      I am not pushing one format over another. In fact, my article is saying that sensor size does NOT matter for the same type of sensor. Those who spent 3 times more for basically the same camera are just trying to justify the highly questionable superiority of their gear even if it means spreading a myth and calling those who are merely presenting facts as foolish or stupid. I’m not stating an opinion mind you. I’m stating FACTS. That’s why I don’t care — not one bit — if you continue believing in the myth that you yourself have doubly debunked in an effort to make sense of it.

      The facts I have presented are immutable. You can’t say that they only works in certain situations. That’s not how facts work. I have presented numerous examples including FILM to make the comparison perfectly fair. Unlike digital where further processing happens behind the sensor, exposing film ends when you click the shutter. Film is the most neutral and the best way to compare different formats. It is constant across different sizes. These are facts that you have completely DENIED and IGNORED.

      For the nth time, I don’t care if you totally ignore the physics and math that I have presented. Just because one does not believe in gravity doesn’t mean it won’t kill him.

      And for the record, I own point and shoot, m43, aps-c, FF and even medium format cameras. I have nothing to gain by presenting facts. Gear whores and posers, OTOH, will distort reality to convince others of their delusions that every pixel of their measly full frame is worth every money they spent. Cough! Cough!!!

      Edit: I wasn’t referring to you in that last statement.

  6. I appreciate the Edit 🙂

    But after all this I am still confused. Can you please summarize in one concise sentence exactly what myth is being debunked?

    1. The myth is that larger sensors gather more light and are therefore less noisy given the same exposure. It’s that simple.

      The article has ballooned to what is now because believers of the myth have twisted the truth to fit their argument namely:

      1) total light gathered determines noise
      2) larger sensor means more total light gathered therefore lesser noise — the solar panel argument
      3) aperture, NOT f-stop, determines total light gathered therefore lesser noise

      In all of these arguments, the proponents show their ignorance of a very basic photography concept: F-STOP. And they keep comparing a camera sensor to a solar panel that’s why they insist on total light.

      That’s the big complicated myth. It’s not just one sentence. You believe in all three of them.

  7. ‘The myth is that larger sensors gather more light and are therefore less noisy given the same exposure.’

    Well that’s no myth: that’s either true or untrue depending on some of the parameters chosen at the time of capture as discussed earlier. Here is an example of when it is true (also easy to come up with one where it is not true): If the same scene and a peak exposure of, say, 0.5 lx-s are projected onto an Olympus EM5 and a Nikon Df, both 16MP cameras, the relative EM5 pixels will be see a signal of about 24k photoelectrons from the sensor – while the Df’s about four times as many. If the AOV is the same that will be true pixel by pixel throughout the image. More signal typically means lower SNR.

    ‘1) total light gathered determines noise’

    If you are referring to the SNR of photographs of the same scene displayed at the same size aotbe, this is correct: more signal means lower SNR and vice versa.

    ‘2) larger sensor means more total light gathered therefore lesser noise — the solar panel argument’

    True or untrue as per your opening statement.

    ‘3) aperture, NOT f-stop, determines total light gathered therefore lesser noise’

    With an ideal thin lens aperture-and-focal length (otherwise expressed in terms of opening angle or f-stop) plus exposure time determine the total number of photons captured per unit area by a sensor aotbe.

    That’s what I believe. Unless there are specific issues that you would like to explore further perhaps we should agree to disagree and leave it at that 🙂

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