"Equivalence" demonstrated: Canon 5D and Panasonic GX1

Started Apr 27, 2013 | Discussions thread
Hen3ry Forum Pro • Posts: 18,218
Question of equivalence; ah, nostalgia!

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.

"Meaningless concept"? -- not theoretically. I grok it.

"Irrelevant" is the word that springs to mind for nearly all photographers nearly all of the time.

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.

The large and medium format users back in the old film days used to waffle on endlessly about quality and whatnot; in the end the (little) 35mm format won out for its smallness, lightness, handiness, and with improvements in film technology, perfectly satisfactory IQ for nearly all amateur and most professional applications.

And here it is all over again with the noose tightening around the "big" format -- now FF (35mm equiv!) and its supporters desperately summoning esoterica to boost their armament as their flailing mirrors fail to repel the smaller format, more technologically advanced visigoths which are swallowing up their outposts one by one.

Just as it did back in the day when the 35mm barbarians were at the IQ gates.

Oh dear! It does bring a tear to the eye. Tear of laughter, that is!

I am one of the "nearly all" and am enjoying both my professional and leisure photography enormously, thanks, with my E-PL3 and such dedicated lenses as the Panny f2.5 14mm (28mm equiv) and the Oly 40-150 zoom (80-300 equiv) at ISO 200 nearly all the time. LOL.

But I really do enjoy seeing the FFers working themselves up into a lather about DoF, total light to the sensor, bokeh, etc. In particular, bokeh. Sure, that is linked to DoF but the biggest contributor to nice bokeh, in my book, is having the light coming through a circular or near circular orifice. Like the Oly f1.8 45mm (90mm equiv, LOL) I use for most portraiture.

Cheers, geoff

 Hen3ry's gear list:Hen3ry's gear list
Panasonic Lumix DMC-GX7 Panasonic G85 Olympus M.Zuiko Digital ED 9-18mm F4.0-5.6 Olympus M.Zuiko Digital 45mm F1.8 Panasonic Lumix G X Vario PZ 45-175mm F4.0-5.6 ASPH OIS +7 more
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