"Equivalence" demonstrated: Canon 5D and Panasonic GX1

Started Apr 27, 2013 | Discussions thread
jrtrent Veteran Member • Posts: 4,897
Re: "Equivalence" demonstrated: Canon 5D and Panasonic GX1

walkaround wrote:

There has been a lot of talk by a few people here about "total light", and how an f/1.4 lens on a m4/3 camera supposedly acts like an f/2.8 in regards to "light on the sensor", etc. No examples have been given in those threads, so I thought I would post some test shots I just did.

Both photos were taken at ISO 160, 1/250, f/2.0
I have not edited the out of camera jpegs in any way. Other than slight differences in the magnification of the two lenses, WB, and the obvious DOF difference, the exposures are equivalent. They are the same. When I print both photos on 4x6, they look the same. "Total light on the sensor" is a meaningless concept. Exposure and density is not.

I'm a little confused by the comparison.  From past threads, wouldn't "equivalent" pictures have meant:

GX1:  50mm, F/2, 1/250, ISO 160

5D:  100mm, F/4, 1/250, ISO 640

I don't know that "total light on the sensor" is a useful concept for me in understanding or using cameras, but the "obvious DOF difference" might not exist--that is, the pictures might look even more the same--if the 5D's lens had been closed down a couple of stops.

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