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

Started Jun 15, 2014 | Discussions thread
Just another Canon shooter
Just another Canon shooter Veteran Member • Posts: 4,691
Re: Very simple:

Anders W wrote:

Just another Canon shooter wrote:

Anders W wrote:

FF has the same noise for equivalent images only if the sensors are equally efficient. But as a rule they are not. Smaller sensors tend to be more efficient than larger. See here:

http://www.dpreview.com/forums/post/53189207

Not true. QE of newer sensors is about 53%, see sensorgen, from m43 to APS-C to FF.

Sensorgen doesn't have data for many of the sensors in my sample and are based on fitting curves to numbers that results from previous curve fitting.

It does, for the most relevant bodies.

Further, QE is an indirect measure

It is what it is, it has a clear definition.

that doesn't take certain facts into account (e.g., fixed pattern noise and read noise).

It should not. Read noise is a different parameter.

My more direct measures are not subject to any of these problems.

I did not read your posts and I do not have to. You are trying to give your own definitions, then to compute the "efficiency", and then what - to compute the noise? But DXO measured the noise. What is the point of your exercise then?

DXO measured 2 stop difference at 18% gray. This is the theoretical factor, so we have the same QE. This is based on the theoretical model here, and also somewhere on the DXO site. So, same QE, as simple as that. We do not really know what it is, but we know they are the same.

About DR - DXO measured that as well. Difference about 1.2 stops or so, short of 2 stops. Since they define ISO as the saturation level, that tells you what the read noise is. Pattern noise is not a problem with newer FF bodies at high ISO - only with Canons at low ISO but m43 cannot even capture so much light, so what is the point of discussing it.

But for that, you need, say, f/1.4 vs. f/2.8, and the sensor would not be able to register at least 1/2 stop of that light, you get a noticeably lower resolution, etc.

I would need f/1.4 vs f/2.8 only if the sensors were equally efficient. My point is that they are not.

Of course, by "for that", I meant to realize the hypothetical "efficiency advantage". Then you must be at equivalent apertures.

What FF can do is to take non-equivalent images, as simple as that.

Yes. Nobody disputes that. What I disputed was your claim that it can take equivalent images just as well as smaller sensors as far as noise is concerned.

Noise and resolution are related, so higher resolution helps offset some part of the noise.

Since smaller sensors tend to be more efficient than larger, that's not the case.

Since they are not, it is not.

Yes. DR is part of the efficiency of the sensor.

It is not. You want to make it though.

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Canon EOS 5D Mark II Canon EF 15mm f/2.8 Fisheye Canon EF 35mm F1.4L USM Canon EF 50mm f/1.2L USM Canon EF 135mm F2L USM +4 more
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