How to properly compare RX-100 and NEX-6 kit high ISO noise?

Started Apr 29, 2013 | Discussions thread
Mel Snyder
Mel Snyder Veteran Member • Posts: 4,088
Re: How to properly compare RX-100 and NEX-6 kit high ISO noise?

The only thing I see in these two "as metered" images is that the NEX and RX-100 metering systems are very different. The RX-100 is clearly more center-weighted than the NEX, and read deep into the shadowed hallway. And the reciprocity of the two sensors are very different.

Proof: The extreme left wall is overexposed in the RX-100 but properly exposed in the NEX.

The faster maximum aperture on the RX-100 allowed the software designer to develop a totally different exposure algorithm because he KNEW the lens would never change on the RX-100. That knowledge enables totally different tradeoffs.

The designer of the NEX could make no such assumption.

"Reciprocity" - which those of us from the film era knew well - is key to dynamic range in sensors as well as film. The sensitivity of sensors and film is not linear. The NEX "jams" the reciprocity curve on only one factor, because it cannot open to an aperture wider than f3.5. That forces the worst case for the reciprocity of the NEX sensor. The RX-100 faces no such single-factor jam.

This is especially prejudicial because you allowed the cameras to "choose" ISO 3200, which has a horrible dynamic range - anyone who has actually shot much at ISO 3200 understands that it's horrific on subjects with considerable peak-to-trough lighting challenges. Again, you jam the test against the NEX, but favor the RX-100 because it can admit more light.

These tests are absurd on the face of it, anyway. One device is an optimized tiny camera that is best of class. The other is an interchangeable lens mirrorless that is, in the opinion of all but the MFT crowd, best of class. Comparing the NEX and RX-100 is as absurd as if someone with a digital Hasselblad came came onto the forum and said, "let's compare." To which I'd say, "sure, I'll put my RX-100 in my pocket, you put your Hasselblad in yours, and let's go test cameras."

Anyone for actually taking photos instead of optical arm-wrestling?

NEX-6 with 50mm Summicron, f2.8

wald wrote:

Summary: The RX100 will beat the NEX cameras with the kit lens in low light.

I did this test a while ago, but not quite as you specified. I think the test you specified would give the same results. I set the lens of both to their widest angle, which gives each the same, 28mm full-frame equivalent, view. I let the cameras meter the scene. they both chose ISO3200, a 1/25s shutter speed, and max aperture. The RX100 gathered more light and made a brighter picture.

The images are all from raw. They are a central crop. They are not resized; viewing 1:1 will give you a 1:1 view of the actual image. The RX100 images will be larger because it is 20megapixels versus the 5N's 16.

NEX-5n as metered

RX100 as metered

I then adjusted the exposure of each picture (I edited the raw in lightroom) to make them equal (well, almost equal). The RX100 has a clear advantage.

NEX-5N, exposure adjusted in post

RX100,  exposure adjusted in post

 Mel Snyder's gear list:Mel Snyder's gear list
Sony Alpha NEX-6 Sony Alpha a7 Sony E 16mm F2.8 Pancake Leica Summicron-M 50mm f/2 Sony E 55-210mm F4.5-6.3 OSS +12 more
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