"Equivalence" demonstrated: Canon 5D and Panasonic GX1

Started Apr 27, 2013 | Discussions thread
Great Bustard Forum Pro • Posts: 42,061
"Adding to the confusion"

walkaround wrote:

Yohan Pamudji wrote:

What you are talking about is using the same exposure settings on 2 different formats--aperture, shutter, ISO--which will result in the same brightness

Yes. You think this is self apparent, but to others it is not. And dpreview adds to the confusion:

"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."

(my emphasis)

The part that I put in bold above is only true (and only interesting) if your primary concern is image noise. If you are concerned, like most people taking a photograph, with "brightness" ie exposure, then it is not true. To the individual pixel or film grain the lens is an f/1.8 lens.

If neither noise nor DOF are an issue, then you can shoot whatever f-ratio and shutter speed you desire.  I believe I asked you the following earlier:


And since you "don't give a sh*t about sensor noise", then what is the difference in "exposure" between f/2.8 ISO 100, f/4 ISO 200, f/5.6 ISO 400, etc.?


So you can save your explanations, I am fully aware of what the equivalence gang defines as "equivalence". I find it funny that I'm being called ignorant and insulted for pointing out what several of you have admitted is accepted fact, even "obvious".

Wasn't it you who said:


Equivalent images all have identical:


- Shutter Speed

- Aperture

- Framing

Anyone who says "equivalence" means something other than the above is an idiot.

Anyone who disagrees with my definition of "equivalence" is an idiot.


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