"Equivalence" demonstrated: Canon 5D and Panasonic GX1

Started Apr 27, 2013 | Discussions thread
olypan Regular Member • Posts: 200
Re: "Equivalence" is not "Equivalence" - try a new terminology.

Great Bustard wrote:

pavinder wrote:

Great Bustard wrote:

pavinder wrote:

Great Bustard wrote:

Similarly to say "these 2 photos are visually equivalent but not technically equivalent" is far more helpful than to just argue about whether they are "equivalent" under some all-encompassing definition.

So, what are your parameters for "visually equivalent" and what are your parameters for "technically equivalent"?  I mean, next thing we know we're going to be talking all sorts of "equivalences" for size, weight, price, AF speed/accuracy, build, etc., etc., etc.

Visually equivalent - very simple.  And exactly what it says. They look the same.

Framing, perspective, what's in focus and what's not, what's light, what's dark, etc.

In other words if you showed someone the 2 photos, they would look and think "yes, it's the same photo".

Well, that's basically Equivalence as I've defined it, then:  same perspective, framing, DOF, shutter speed (motion blur), and display size.

Well 3 out of 5 is not quite the same.

Shutter speed and display size are quantitative, not qualitative.

They're all quantative.  We can quantify perspective (subject-camera distance).  We can quantify framing (width and height of the scene on the focal plane).  We can quantify DOF (total distance front and back of the focal plane that is within critical focus).  In other words, they are all quantative just like shutter speed and display size.

Here, let me ask you a question:  would anyone disagree that 25mm f/2.8 1/100 ISO 400 with the 14=54 / 2.8 on an Olympus E1 is equivalent to the same settings with the 12-35 / 2.8 on an Olympus EM5?  I'm thinking no one would say they are not "equivalent", despite the fact that the noise, detail, dynamic range, etc., would all be quite different.

Thus, I see no reason not to use the word "equivalent" to describe photos that have the same perspective, framing, DOF, shutter speed, and display size even when other elements of IQ are not necessarily the same.

Keep digging. You should reach Australia soon. Pop in and see John King. He could maybe give you some wisdom, or at least the "entertainment" you so enjoy.

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