"Equivalence" demonstrated: Canon 5D and Panasonic GX1

Started Apr 27, 2013 | Discussions thread
Yohan Pamudji Senior Member • Posts: 2,874
Re: One last stab

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.

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".

No, you are being called ignorant for calling what you're pointing out as "equivalence", which it isn't.  And you still persist.  Nobody is disagreeing with the premise that equal exposure settings on different sensor sizes result in the same brightness.  People are just disagreeing with your claim that that represents equivalence, which it doesn't no matter how much you rage against it.

And with that I contribute another post toward 150 so this thread can die a peaceful death.

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