On recent cameras: EM-1, XT-1, A6000 ...

Started 10 months ago | Discussions thread
EinsteinsGhost
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Speaking of ISO
In reply to blue_skies, 10 months ago

SirPalomid wrote:

Well, I understand what you're saying. I'm not saying that Sony is an awful camera, and somebody cannot love it or something like this. Just to point out that "1 stop difference" it's not what I've experienced myself, and "Fuji overstates ISO" is exaggerated - almost everybody do so, Sony and Olympus (in E-M5 for sure) too. If I had NEX right now, I'd happily perform this comparison test for you.

Although I have Panasonic GX7 and Canon 6D, so I may do test with them (with Panasonic as reference as "right ISO"), and if I'm wrong, and difference is really 1 stop, than I apologize.
I didn't want to harm you in any way with my words, so excuse me.

You'd have to control the image - e.g. a gray card under even lighting - to compare the cameras.

If you take a more complex scene, then metering mode and exposure algorithm may vary wildly.

Sony cameras, especially if you elect DRO to auto, will expose to the left under low light, meaning that the Sony actually under-exposes the image.

You compare that with the competition that actually exposes to the right (and blows out highlights), which almost over-exposes the image. On a smaller sensor camera, you'd have no choise, as it is a better strategy to blow out the highlights somewhat to regain some details in the shadows. Hence the difference in algorithms. The same is true for older, less DR rich, larger sensors, such as in your Canon.

So, if ISO was identical, you should see a slower speed on the Sony (0.7EV is a good guess) than on the competition.

But in the above example, you see that the competition is already getting 0.7EV more from for the same scene.

If you still see 1/3rd of stop of difference, assuming Sony being lower, you have to add this 0.7EV and you end up at a full stop of difference.

Do a grey card test, under tungsten (controlled) lighting, with center-spot metering on all cameras with DRO off. How do these test compare? I am sure that you will mimic dpreview and DxO's findings...

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Cheers,
Henry

It might also be worth pointing out in the OP that X-T1 is also limited to ISO 200 with RAW, hence a range of 200-6400. I believe OM models are too. A base ISO of 200 was one of my three major issues with NEX-3, not an ideal situation with 1/4000s shutter limit even with f/2.8 lenses.

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