Crop Factor, Low Light and Aperture with m4/3 lenses? Part 2

Started Jun 16, 2014 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Reply to Just another Canon shooter

The old thread expired a second time (after being pruned) so I answer here instead:

Just another Canon shooter wrote:

Anders W wrote:

Noise can't be "blurred". It's not affected by the optical resolution. The E-M1 shows less noise.

Of course it can, it is called NR,

NR blurs the detail. It reduces the noise.

It reduces the noise by blurring it.

A matter of semantics. My assumption was that no NR is applied in any of these cases.

The noise in the deep blue has very non-Poisson structure, as simple as that.

Can you please specify mathematically what you mean by a non-Poisson structure and how you can see or measure the deviation from Poisson in this case?

which can be done after the demosaicing, or incorporated in the demoasicing algorithm. Shot noise is of Poisson type, even on a Bayer sensor. If we make it B&W for simplicity, it has a well defined structure and spectrum. Missing high frequencies with the low frequencies present is an evidence of blurring, or NR, or call it whatever you want.

So are you saying that ACR secretly applies more NR to the E-M1 than to the other cameras although the NR sliders are set 0 in all cases?

You cannot separate demosaicing from NR. The old ACR process, for example, has "hidden NR" in it, by your logic.

So are you saying that ACR uses a different demosaicing algorithm for the E-M1 than for the other cameras?

Go to ISO 100. The deep blue square has more blurred borders compared to the others. Look at the 6D crop - no such thing.

The borders are a matter of resolution. Note what I already said about the E-M1 shot not being appropriate for judging resolution.

Resolution magically changes from one color to another?

It does not need to do that in order to blur the border.

It blurs one border but not another, while the camera next to it does not do that.

I have seen plenty of examples where different colors are differently blurred (especially when the border is black) due to properties of the lens rather than the sensor or the processing of the RAW file.

Lens aberrations cannot change the structure of the noise of a uniform target.

Right. That's one thing I had in mind when I said noise can't be blurred.

But processing can.

Sure. I was just explaining what I had in mind when I said noise can't be blurred.

I'd additionally appreciate a response to the following question included in my previous reply:

We had a poll here recently where two anonymous images were pitted against each other. One had a one stop advantage for SNR at 18 percent and the other had a one stop advantage for DR, but the poll participants didn't know anything about that in advance. The question asked was:

Which picture has higher image quality as far as noise is concerned?

What do you think the verdict of the poll participants was?

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +28 more
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