"Equivalence" demonstrated: Canon 5D and Panasonic GX1

Started Apr 27, 2013 | Discussions thread
Great Bustard
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You say, "An f-stop is an f-stop...
In reply to Hen3ry, Apr 29, 2013

Hen3ry wrote:

An f-stop is an f-stop, a shutter speed is a shutter speed, and an ISO is an ISO (although various manufacturers fudge the latter a little just as in the old days the film manufacturers fudged things a little in respect of sensitivity). So f2 @ 1/200 with a 25mm focal length lens on m43 produces an image of near enough to the same density and general characteristics as f2 @ 1/200 with a 50mm on FF.

...a shutter speed is a shutter speed, and and ISO is an ISO."  But apparently you stop short of focal length.  That is, you didn't say "A focal length is a focal length."

I find that omission curious.

That is, just as the effect of 25mm on mFT has the same effect as 50mm on FF, the effect of f/2 on mFT has the same effect as f/4 on FF.  And yet you feel "an f-stop is an f-stop" but apparently don't think that "a focal length is a focal length".

Like I said -- curious.

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