sanj said:aceflibble said:With that in mind, the only part of the 6D2's measurements which is at all surprising is how low the true sensitivity is. ISO 100 is actually 63 and ISO 200 is actually 127. That's a record-low for Canon, and I believe a record-low for any SLR. That means that using like-for-like settings, the 6D2 underexposes by nearly two thirds of a stop. [Is this a fact? Can you prove it?] To compensate and get the same exposure you'll need to either use a faster lens/open up (potentially dropping in sharpness and increasing vignetting), lower your shutter speed (yay motion blur) or raise the ISO (more noise and less exposure latitude to play with).
That's a huge problem. Yes, the 80D also severely overrates its ISO, but that wasn't quite this bad. Yes, Fuji do it too, but again, not by this much. Nikon and Sony haven't, as far as I'm aware, ever fudged their ISO sensitivity by any more than half a stop. (Though even half a stop is too much to get away with, in my view.)
No, this is not a fact. It is horse poop. If the 6DII is severely overrated... or whatever... so is the 80D and 60D, and some older xxxD Canon bodies, all to approximately the same degree, because I take photos of the same subject from different angles using the same exposure settings all the time with these cameras. I rely on that.
Also, so too must my Sekonic flash meter, because when I'm using a whole bunch of strobes and/or speedlites, especially when it's a new lighting setup, I'll usually take a reading with Sekonic, and it's pretty damned close.
But anyways, here is proof. Using exactly the same tripod location and lighting, I took 2 pictures of a ColorChecker, on the left with an 80D and on the right a 6D Mark II, both at 1/320 ISO 100. Don't mind pixel peeping sharpness, because I just used the shutter button autofocus and took a single shot; that wasn't the point. The point is, both are identically exposed, or at least close enough not to matter. Certainly not by some massive ISO difference.
Full resolution: http://talys.icxi.com/cr/20170919/6D2_80D_ISO_Compare.jpg
Edit -- no idea why attachments never work for me
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