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

Started Jun 15, 2014 | Discussions thread
Re: Very simple:
1

Just another Canon shooter wrote:

Anders W wrote:

Just another Canon shooter wrote:

Anders W wrote:

So you are using the DXO data to compute some "efficiency factor" that you define yourself to draw conclusions about noise, which was your starting point to begin with?

As I already pointed out, I use DxO data to compute the efficiency of the sensors to be compared. I do so on the basis of four different measures of signal-noise performance. What's wrong with that?

What good does it do to compute what you want to compute? You have the noise measured, period.

Not the noise but the signal-noise performace.

Then you compute something and you have to convince the public that this something is relevant. Sorry, I have no other way to explain it.

Yes, and that motivation is provided in the post you said you didn't want to read. In short, a difference in efficiency with my measures shows up as a deviation from the two-EV difference between FF and MFT that you would expect based on the principles of equivalence.

The most complete data I have seen on the DXO site are the whole SN curves for each channel. Then you can use them, and the color coefficients table, to try to compute the noise at each primary color. Then you still need to compute the noise for, say, skin tones, etc. It would be an interesting exercise, but I'd rather look at pictures.

DxO does not provide complete SNR data per color channel so I can't use that. I use overall SNR.

No I didn't misinterpret anything. The per-pixel signal-noise performance of two equally efficient sensors will not be the same if one has more pixels than the other. The performance of the sensor with more pixels will be worse on a per-pixel basis.

You did.

No I didn't.

I am talking about resolution as resolving detail.

So am I.

An almost noiseless photo taken with a Coca-Cola glass is worthless.

Yes. So what. That has no bearing on what we are talking about.

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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