"Equivalence" demonstrated: Canon 5D and Panasonic GX1

Started Apr 27, 2013 | Discussions thread
Great Bustard Forum Pro • Posts: 42,724
Re: "Equivalence" is not "Equivalence" - try a new terminology.

pavinder wrote:

Seems to me these endless arguments mainly come down to what people interpret "equivalent" to mean.

There are quantitative interpretations (amount of light hitting sensors etc.) and qualitative interpretations (framing, exposure, DOF etc).

There's absolutely no argument that a larger sensor will generally capture a cleaner, less noisy image.  As an analogy 8x10 negatives contain more information than 110 cartridge film negatives, and digital sensor sizes are simply an electronic version of this.

So perhaps we just need to introduce extra terminology to stop these petty and ultimately irrelevant arguments.

As photographers we simply want to make an image that looks a certain way.
What that means, I would have thought, is pretty obvious:
1. what's in the frame, 2. how light or dark the various parts look, 3. DOF, 4. perspective.

Anything else, such as noise levels, are technical issues, they're not part of the first-level aesthetic qualities of the image as listed above.

Of course to some photographers, only the items 1-4 are relevant, and the technical considerations are considered "extra stuff" which rarely becomes important (unless, for example in extremely low light, they become extremely problematic). As long as their image is "clean enough" many people are happy.  For example if people are printing small, or only shooting for the web.

In this case "equivalent" simply means "looks the same" in those qualities mentioned.  If you took two photos, one with a MFT and the other with a FF, stuck them on the web and they "look the same" then they're "equivalent".

We don't care what f-stop it was, what focal length was used, etc.  And we absolutely don't give a 5h1t at all whether the total amount of light on the sensor was more, or less, or more per unit area or whatever!!

It looks the same = it's equivalent.

So what I'm suggesting is simply that these different interpretations be given different names and then there should be be no more need for bickering.  Of course people will then find something else to bicker about, but that's not our concern here.

I suggest "quantitatively equivalent" and "qualitatively equivalent", or perhaps "aesthetically equivalent".  Yes, I know these are also ambiguous terms, but at least it's providing some basis for mutual agreement.

And most of the threads on this topic would be reduced to a handful of posts or until someone points out "yes, they're aesthetically equivalent but not quantitatively equivalent " or vice versa.

I asked earlier today:


In terms of the visual properties of the final photo, what parameters do you think are "more equivalent" than the parameters I have used [photos with the same perspective, framing, DOF, shutter speed, and display size]?

From where I sit, I find it ironic that so many would be happy to define "Equivalent" as photos with the same AOV and exposure, despite the fact that they would have rather different visual properties.

What do you think?

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