The myth of the large sensor "high ISO advantage"

[jonrobertp]

Engineers always use sniff tests. First sniff test: "Smaller sensors are inherently more sensitive than larger sensors" makes no sense.

They are. An APS-C camera with AOTBE to an FF with regards to DoF and ISO settings will have a faster shutter speed for a given scene.

Second sniff test: "With a two minutes of calculation I have proved 10 years of debate wrong." Nothing personal, but unless you have two Phd's, it's pretty unlikely that you've just discovered a myth everyone else has missed.

Don't mistake your misunderstanding as me being wrong. Again, show me the proof. I have various reputable sources that say/demonstrate what I'm saying. Do you?

And since when are PhD's required to post here? How many do you have?

Remember, there are a few posters on dpr who regard themselves as the only ones with the whole truth. They seldom or never post their own work, they have overly high regards for themselves, and it's pointless to give them more ammo to argue over. Many ordinary ppl are taken in by them.

Much better to do ur own research and think for yourself.

And avoid the annoyance.

 

[Aur]

it's the difference in area (physical size) that gives the larger sensor the advantage (mostly irrelevant of pixel size).

--
https://www.flickr.com/photos/skersting/

I believe this is wrong

afaik, it's individual pixels size that is accounting for the higher (cleaner) ISO

HTC has made this argument, their argument was that even though the megapixels and sensor size of their new phone is similar, their new model has better performance in low light and higher ISO

when ppl tested that, it was found to be true

They call it Ultrapixel, what they did was take the same resolution, but managed to increase the size of their pixels, to 2.0 µm

HTC slide:



It is about how much light each pixel lets in, the fact larger sensors tend to have better light performance, is enabled by

-the pixel size, larger pixels capture more light

-indirectly through the sensor size, which enables you to use larger pixel sizes, but, a larger sensor does not have to have larger pixels, it simply allows you to use larger pixels more easily

-the lens letting in more light

it is especially the pixel size in combination with the lens causing the full frame to have cleaner ISO, the large sensor size, is part of the machanic that enables large pixels

but as the link I showed pointed out, larger sensor size does not always mean more light, larger sensors generally have larger pixel sizes, but not always

 

[Allan Olesen]

Yes, the f-number determines exposure; however aperture diameter/depth of field and shutter speed determine the total quantity of light. I thought it was pretty clear I was talking about a given field of view.

You can't have both the same aperture and DOF...not even if you change distance/FL for the same recorded FOV (although the DOF may be very close to the same).

Sportyaccordy is right. If you have...:

• the same aperture diameter
• the same field of view
• the same distance to the object in focus
• any sensor size

... then you will have the same DOF.

 

[crashpc]

Theory is nice thing, but in real world, you have it wrong.

1) Almost nobody shoots for equal DoF

2) with larger sensor you gain more resolution even with equivalent DoF

3) you can trade this for denoise

4) get real product comparsion. There are times where smaller sensor can be better, there are times and products where it fails miserably. I might get very close with small sensor at times - when equalisated parameters need to be set. At times where it doesn´t, bigger system smokes the smaller one.

5) stop trolling.

 

[steephill]

A digital image is a data file which is essentially a matrix of colour information. It has no physical dimensions so far as pixels are concerned. The pixels in an image file are not the same thing as the pixel in a sensor. When it comes to making prints there is no magnification involved, instead there is a mapping exercise in which your computer tells the printer to print a pattern of coloured dots based on the colour information matrix in the image file. All it has to work on is the position of the dot and the colour required. The size of the print is determined by the number of dots you have and the density you want to print them at. Sensor pixel size is irrelevant at this stage.

If you strip the exif data from the file there is no way for the printing chain to know whether the colour dot pattern came from a large or small sensor. Assuming the same number of pixels in each image it has to treat them identically i.e. no difference in magnification.

As noise in the digital world is an error there is no logical explanation as to why your computer should make suddenly make more errors when sending a data array derived from a small sensor than from a larger one. If there is more noise in the image from the small sensor it arises at the capture stage, not at the printing stage and has nothing to do with magnification.

 

[cainn24]

The advantage of larger formats is larger pixels. It's like trying to catch rain with teacups vs catching rain with large buckets. The large buckets will have more rain (light) per pixel and that's what gives it an advantage.

--
https://www.flickr.com/photos/skersting/

here's a good article about the water bucket argument

http://www.clarkvision.com/articles/does.pixel.size.matter/

it holds up, on the condition that the larger sensor also has larger pixel size, which is usually the case, but not always

The pixel size of the larger sensor doesn't matter since a larger number of smaller pixels can collect the same total amount of light as a smaller number of larger ones (just as ten 1 liter buckets can collect the same total amount of rain as five 2 liter buckets, assuming they cover the same area).


Noise differences between two sensors of different resolutions but the same size at very high ISOs is a product of increased read noise not some mythical decreased light-gathering capacity.

Horribly misleading illustration. What it should be showing is a larger number of smaller buckets covering the same area as a smaller number of larger buckets, and without the wasted space since that really isn't an issue in reality.

 

[crashpc]

The advantage of larger formats is larger pixels. It's like trying to catch rain with teacups vs catching rain with large buckets. The large buckets will have more rain (light) per pixel and that's what gives it an advantage.

--
https://www.flickr.com/photos/skersting/

here's a good article about the water bucket argument

http://www.clarkvision.com/articles/does.pixel.size.matter/

it holds up, on the condition that the larger sensor also has larger pixel size, which is usually the case, but not always

The pixel size of the larger sensor doesn't matter since a larger number of smaller pixels can collect the same total amount of light as a smaller number of larger ones (just as ten 1 liter buckets can collect the same total amount of rain as five 2 liter buckets, assuming they cover the same area).

You f***ed up your own assumption. Of course it matters as you have larger sensor. You basically don´t have enaugh pixels to merge, to make it equal to actual large sensors. You´d need 1Gpx FF sensor. Not 13-20Mpx 1/1,3" sensor.

Noise differences between two sensors of different resolutions but the same size at very high ISOs is a product of increased read noise not some mythical decreased light-gathering capacity.

It is more than that. Depends on technology, and actual sensor piece.

Horribly misleading illustration.

Very good illustration.

What it should be showing is a larger number of smaller buckets covering the same area as a smaller number of larger buckets,

It shouldn´t. Because this is not what happens.

and without the wasted space since that really isn't an issue in reality.

It is. Especially for smallest pixels!

 

[Allan Olesen]

I have been waffling back and forth between moving to a Sony A7 or A6000, and looking at DxOMark's low light sensor rating I think I realized something kind of interesting.

Interesting, yes. But not really new. This topic has actually been beaten to death here on dpreview. To summarize:

1. At any given combination of DOF, FOV, subject distance and scene light, the sensor will receive the same total amount of light*, no matter what your sensor size is.
2. With the same total amount of light, most modern sensors will have roughly the same noise in the final photo, no matter what the sensor size is. But if there is a difference, it is often slightly in favor of the smaller sensors.
3. Consequently, if you are limited by a minimum required DOF which all your cameras are able to reach, there is not really a low light noise advantage to the larger sensor.

*: Of course assuming that the light path to the sensor have the same transmission loss. So if you use an ND filter or an SLT camera, the rule doesn't hold up.

So the question is: Are you in reality limited by a minimum required DOF in low light situations?

I know that I am usually not. In low light, I will almost always open up my aperture as much as I can. If I stop down a bit, it is only to get better general sharpness (because my lenses perform worse fully open), not to get more DOF.

In most of the situations where I need long DOF, I have plenty of light for base ISO. And then the tables are turned. Now the larger sensor can receive more total light before it saturates, and that means that it will end up with less noise in the final photo.

So in reality, the larger sensor will very often win the noise contest.

First of all, correct me if I'm wrong, but sensitivity across formats is not really equivalent, and smaller sensors are inherently more sensitive than larger sensors for a given DoF & shutter speed length. I.e. if you have the same ISO, aperture diameter & shutter speed in front of two different size sensors, the larger sensor will have a dimmer exposure due to the given volume of light being spread over a larger area.

With that in mind, FF has 1.2 stops/2.36 times more sensor area than APS-C. So correct me if I'm wrong, but if an APS-C sensor is rated at ISO1000 for some low light S/N metric, a FF sensor with equivalent performance per unit of area will be rated at ISO2360 for the same metric, correct?

Correct. But the A7 does not have the same area performance as the a6000. And that is the main problem with your comparison: The A7 does not have typical FF performance.

Sony's first three cameras with OSPDAF - a99, NEX-6 and A7 - did all have worse low light performance than comparable non-OSPDAF cameras with Sony sensors, even when compensating for the SLT mirror in the a99. I have never seen a good reason for this, but it is quite clear when you compare DxO numbers. With the a6000, Sony seems to have made an OSPDAF sensor without this OSPDAF penalty.

So if you compare the a6000 to any other newer FF camera with Sony sensor and redo your math, you will see that you get roughly the same noise at the same DOF. The a6000 will not have a noise advantage. (But it will have a DR disadvantage in good light.)

 

[Lab D]

I always tell everyone it is like a thin super model and an overweight person laying in the sun at the beach. Both will tan/burn at the same rate. Larger people do not tan/burn faster, but more sunlight hits their bodies.

The both have the same exposure to the sun.

 

[gloaming]

And since when are PhD's required to post here? How many do you have?

He he....!! I don't think he saw that coming.

 

[Lab D]

I have been waffling back and forth between moving to a Sony A7 or A6000, and looking at DxOMark's low light sensor rating I think I realized something kind of interesting.

First of all, correct me if I'm wrong, but sensitivity across formats is not really equivalent, and smaller sensors are inherently more sensitive than larger sensors for a given DoF & shutter speed length. I.e. if you have the same ISO, aperture diameter & shutter speed in front of two different size sensors, the larger sensor will have a dimmer exposure due to the given volume of light being spread over a larger area.

With that in mind, FF has 1.2 stops/2.36 times more sensor area than APS-C. So correct me if I'm wrong, but if an APS-C sensor is rated at ISO1000 for some low light S/N metric, a FF sensor with equivalent performance per unit of area will be rated at ISO2360 for the same metric, correct?

Well when you apply that math to the A6000 and A7 something interesting happens. The A6000 is rated at ISO1350 for DxO's 30db low light S/N test, and the A7 is rated at ISO2248. You do some quick math and realize that if the sensors are supposed to be equivalent, either the A7 should be rated at ISO3186 or the A6000 should be rated at ISO950. That's half a stop!

What's the practical impact of that? If you have a low light scene and two equivalent lenses wide open on the two cameras (i.e. the 24 1.8 & the 35 2.8), the A7 will have half a stop more noise. Yes, you will be able to bump up to a "higher ISO", but that's meaningless- you will have to up your ISO to have an equivalent picture (same shutter speed and depth of field) on the bigger sensor as it has inherently dimmer exposures than the smaller sensor.

Does this mean I won't get the A7? Probably not though I might go for the A7R as it somehow claws back most of that missing half a stop. Plus my legacy lenses will work a lot better on the full frame sensor naked than on a crop sensor through a focal length reducer. So there are other considerations to make. But my point is it might be time to change how we look at "high ISO" performance, and create a new metric to normalize it to sensor area. To really compare apples to apples ISO performance between formats you have to use a correction factor. If my math is correct it is pretty much the crop factor between the two formats squared. I.e. Sony APS-C has a crop factor of 1.536 vs Sony FF, so to compare the two you have to either divide the FF ISO or multiply the APS-C ISO by 1.536^2 (the 2.36 I referenced before which is the ratio of the two sensor areas).

This has other implications as well. A little 1/2.3 sensor at ISO100 is operating at a sensitivity equivalent to ISO3500 on a full frame. No wonder dynamic range and color sensitivities are so much worse.

Anyways I just thought that was interesting.

You hear this over and over from small format supporters, but less DOF = better subject isolation and more creative options.

True, but there is more to this. (see below)

Greater DOF control is one of the main reason of getting a larger sensor.

OK, the keyword there is "control". But there is a problem with this thinking.

The"everything in focus" is the curse of phone cameras and one reason 35 mm film shots looks often more attractive and interesting than modern, sharp but flat looking, digital shots with small sensors.

I am sure we agree smartphones are very different from 1 inch sensors, M43, and APS-C and lumping them in the same group is disingenuous.

But if you dont care much for this creative option, sure - the smaller the sensor - the better. "At the same DOF".

Here are some points you are missing. Larger formats do offer greater control but at a price. For example, as the OP mentioned if you try to get the same DoF with a FF camera as an APS-C camera, image quality can suffer slightly. Next, the shallower the DoF the more lightly one is to have focus errors or more noticeable focus errors (front/back focus). Finally, while it is possible to reduce the DoF with software, it is near impossible to increase it (except via multi-exposures). I can take any image and make it look like it was shot with a 1 stop wider aperture pretty easily and it would be near impossible to tell (above that it gets more difficult and things such as fine hair become problematic). I can't go the other way though.

So we are left with, which is better for the individual? If a FF owner shoots 70+% of the time wide open, then I would never suggest switching to a smaller format. If an M43 users is happy with the DoF the is getting and doesn't want anything shallower most of the time, then switching may only serve to reduce IQ (if same DoF is use).

For 90% or more of what an average joe shoots Rx10 is more than enough.

The RX10 has a short lens (very slow zooming too). The FZ1000 is a significantly better camera with a lower price. If they offer the DoF one wants and he is happy with indoor performance, they yes.

Like I mentioned I can reduce DoF with SW similar to a 1 or maybe 2 stop wider lens, but after that it becomes noticeable.

But you are correct, a 1 inch or m43 sensor does perform better than a FF sensor if the same DoF is used.

I like to error on the side of caution. I'll use a slightly larger DoF and make sure focus is nailed. If later I want something a little shallower, I can easily make some simple changes (just as anyone would with softening skin). If focus is off or DoF is too shallow, there is little one can do.

Of course by using caution and a slightly wider DoF, it allows me to use a smaller/lighter lens.

--
::> I make spelling mistakes. May Dog forgive me for this.

 

[cainn24]

The advantage of larger formats is larger pixels. It's like trying to catch rain with teacups vs catching rain with large buckets. The large buckets will have more rain (light) per pixel and that's what gives it an advantage.

--
https://www.flickr.com/photos/skersting/

here's a good article about the water bucket argument

http://www.clarkvision.com/articles/does.pixel.size.matter/

it holds up, on the condition that the larger sensor also has larger pixel size, which is usually the case, but not always

The pixel size of the larger sensor doesn't matter since a larger number of smaller pixels can collect the same total amount of light as a smaller number of larger ones (just as ten 1 liter buckets can collect the same total amount of rain as five 2 liter buckets, assuming they cover the same area).

You f***ed up your own assumption. Of course it matters as you have larger sensor. You basically don´t have enaugh pixels to merge, to make it equal to actual large sensors. You´d need 1Gpx FF sensor. Not 13-20Mpx 1/1,3" sensor.

That comment was made in the context of comparing two sensors of the same size but different pixel counts since Aur was implying that the large sensor advantage goes away if its pixels aren't actually bigger than the ones on a smaller sensor.

It doesn't.

Noise differences between two sensors of different resolutions but the same size at very high ISOs is a product of increased read noise not some mythical decreased light-gathering capacity.

It is more than that. Depends on technology, and actual sensor piece.

That we are talking about sensors of the same generation is implied. Or at least it should be.

What it should be showing is a larger number of smaller buckets covering the same area as a smaller number of larger buckets,

It shouldn´t. Because this is not what happens.

It's exactly what happens when we are comparing two sensors of the same size with different pixel counts. In each case the resulting image is a product of the same total amount of light.

and without the wasted space since that really isn't an issue in reality.

It is. Especially for smallest pixels!

Then you'll need to explain how a 36MP D800/D810 has better normalized SNR/DR than the 16MP D4s at low ISOs (even ones that both cameras share). That simply doesn't happen if the D800/D810 is collecting less light.

 

[Lab D]

Engineers always use sniff tests. First sniff test: "Smaller sensors are inherently more sensitive than larger sensors" makes no sense.

They are. An APS-C camera with AOTBE to an FF with regards to DoF and ISO settings will have a faster shutter speed for a given scene.

Second sniff test: "With a two minutes of calculation I have proved 10 years of debate wrong." Nothing personal, but unless you have two Phd's, it's pretty unlikely that you've just discovered a myth everyone else has missed.

Don't mistake your misunderstanding as me being wrong. Again, show me the proof. I have various reputable sources that say/demonstrate what I'm saying. Do you?

And since when are PhD's required to post here? How many do you have?

I have yet to see a BSI FF sensor. Smaller sensor often use better technology and for other reasons perform better on a per area basis.

If you take the section of a FF sensor equal the size/area of the latest 1 inch sensors, it simply would not give you the same results. This is why when you account for using the same DoF with a small and large sensor, the smaller sensor almost always yields the better image.

 

[crashpc]

The advantage of larger formats is larger pixels. It's like trying to catch rain with teacups vs catching rain with large buckets. The large buckets will have more rain (light) per pixel and that's what gives it an advantage.

--
https://www.flickr.com/photos/skersting/

here's a good article about the water bucket argument

http://www.clarkvision.com/articles/does.pixel.size.matter/

it holds up, on the condition that the larger sensor also has larger pixel size, which is usually the case, but not always

The pixel size of the larger sensor doesn't matter since a larger number of smaller pixels can collect the same total amount of light as a smaller number of larger ones (just as ten 1 liter buckets can collect the same total amount of rain as five 2 liter buckets, assuming they cover the same area).

You f***ed up your own assumption. Of course it matters as you have larger sensor. You basically don´t have enaugh pixels to merge, to make it equal to actual large sensors. You´d need 1Gpx FF sensor. Not 13-20Mpx 1/1,3" sensor.

That comment was made in the context of comparing two sensors of the same size but different pixel counts since Aur was implying that the large sensor advantage goes away if its pixels aren't actually bigger than the ones on a smaller sensor.

It doesn't.

Noise differences between two sensors of different resolutions but the same size at very high ISOs is a product of increased read noise not some mythical decreased light-gathering capacity.

It is more than that. Depends on technology, and actual sensor piece.

That we are talking about sensors of the same generation is implied. Or at least it should be.

What it should be showing is a larger number of smaller buckets covering the same area as a smaller number of larger buckets,

It shouldn´t. Because this is not what happens.

It's exactly what happens when we are comparing two sensors of the same size with different pixel counts. In each case the resulting image is a product of the same total amount of light.

and without the wasted space since that really isn't an issue in reality.

It is. Especially for smallest pixels!

Then you'll need to explain how a 36MP D800/D810 has better normalized SNR/DR than the 16MP D4s at low ISOs (even ones that both cameras share). That simply doesn't happen if the D800/D810 is collecting less light.

Okay. You made it straight for me, therefore now I understand and AGREE.

As I didn´t make that sensor, and there is no vital data available, I can´t explain it to you. But I can say that DR is actually not fixed property of pixel size. You can make it VERY different, depending on many aspects, intentions and needs etc. There are some parameters needed to "be delivered" with the device which avoid you to make it greater DR. for example speed, size, price, and many more.

 

[Aur]

I always tell everyone it is like a thin super model and an overweight person laying in the sun at the beach. Both will tan/burn at the same rate. Larger people do not tan/burn faster, but more sunlight hits their bodies.

The both have the same exposure to the sun.

that theory is kind of dangerous

it works in theory as long as pixels sizes of all manufacturers is the same, in reality they're not

you can have a massive sensor and still have horrible low light performance because your pixel size is 0.6µm

you can make a simplificaiton

"larger sensors have in general bigger pixel sizes"

but that is a dangerous and oversiplified explanation, it can be untrue also, those things are misleading and will often turn out to be wrong

 

[mostlyboringphotog]

A digital image is a data file which is essentially a matrix of colour information. It has no physical dimensions so far as pixels are concerned. The pixels in an image file are not the same thing as the pixel in a sensor. When it comes to making prints there is no magnification involved, instead there is a mapping exercise in which your computer tells the printer to print a pattern of coloured dots based on the colour information matrix in the image file. All it has to work on is the position of the dot and the colour required. The size of the print is determined by the number of dots you have and the density you want to print them at. Sensor pixel size is irrelevant at this stage.

If you strip the exif data from the file there is no way for the printing chain to know whether the colour dot pattern came from a large or small sensor. Assuming the same number of pixels in each image it has to treat them identically i.e. no difference in magnification.

As noise in the digital world is an error there is no logical explanation as to why your computer should make suddenly make more errors when sending a data array derived from a small sensor than from a larger one. If there is more noise in the image from the small sensor it arises at the capture stage, not at the printing stage and has nothing to do with magnification.

 

[sportyaccordy]

Yes, the f-number determines exposure; however aperture diameter/depth of field and shutter speed determine the total quantity of light. I thought it was pretty clear I was talking about a given field of view.

You can't have both the same aperture and DOF...not even if you change distance/FL for the same recorded FOV (although the DOF may be very close to the same). Are you talking about recorded FOV or lens FOV? (it doesn't actually matter in regards to light recorded)

Aperture diameter != aperture. Aperture diameter is what you get when you replace the focal length with the F in the F-stop. So a 24mm lens at F/5.6 = 24/5.6 = 4.28mm which would be equivalent to a 35mm lens at 35mm/4.28mm= ~F/8(.1666666). Depth of field is directly proportional to aperture diameter regardless of focal length.

On the basis of light, different sized sensors record the same amount of light per area.

Yes, for a given exposure level. But for a given aperture diameter, the total volume of light is the same, and the exposure on the larger sensor will be dimmer.

I think you are mixing too many variables in your understanding (and our discussions). Sensor size does not equate (necessarily/directly) to pixel size/density.

I never claimed they did.

The ISO performance capabilities of smaller pixels (same size sensor) comes from oversampling/downsampling.

In the end, it comes down to enlargement for display, and pixel count/size is *fairly irrelevant in that regards... it's enlargement of the sensor's physical size to the final display's physical size.

*(as long as the pixel size is ~ 10um or less)

--
https://www.flickr.com/photos/skersting/

Enlargement is a factor for sure, but for a given aperture diameter/DoF and shutter speed you have the same signal across formats, so things cancel out. I.e. on a larger sensor you will have to turn up the gain to maintain exposure, and to a degree that after the fact gain equates to a kind of magnification. So unless you are putting more light (product of shutter speed and aperture diameter), the advantages become a lot less dramatic and more academic (i.e. diffraction effects).

 

[Lab D]

I always tell everyone it is like a thin super model and an overweight person laying in the sun at the beach. Both will tan/burn at the same rate. Larger people do not tan/burn faster, but more sunlight hits their bodies.

The both have the same exposure to the sun.

that theory doesn't work in practice

it works in theory as long as pixels sizes of all manufacturers is the same, in reality they're not

you can have a massive sensor and still have horrible low light performance because your pixel size is 0.6µm

you can make a simplificaiton

"larger sensors have in general bigger pixel sizes"

but that is a dangerous and oversiplified explanation, it can be untrue also, those things are misleading and will often turn out to be wrong

Did you read the A7s review???

One of the conclusions was "So much for more pixels (smaller pixels) = more noise, a fallacy we've now debunked a number of times in this review."

btw, smaller sensors used often use better tech (like BSI), so really you should argue the other way.

 

[sportyaccordy]

I have been waffling back and forth between moving to a Sony A7 or A6000, and looking at DxOMark's low light sensor rating I think I realized something kind of interesting.

Interesting, yes. But not really new. This topic has actually been beaten to death here on dpreview. To summarize:

1. At any given combination of DOF, FOV, subject distance and scene light, the sensor will receive the same total amount of light*, no matter what your sensor size is.
2. With the same total amount of light, most modern sensors will have roughly the same noise in the final photo, no matter what the sensor size is. But if there is a difference, it is often slightly in favor of the smaller sensors.
3. Consequently, if you are limited by a minimum required DOF which all your cameras are able to reach, there is not really a low light noise advantage to the larger sensor.

*: Of course assuming that the light path to the sensor have the same transmission loss. So if you use an ND filter or an SLT camera, the rule doesn't hold up.

So the question is: Are you in reality limited by a minimum required DOF in low light situations?

I know that I am usually not. In low light, I will almost always open up my aperture as much as I can. If I stop down a bit, it is only to get better general sharpness (because my lenses perform worse fully open), not to get more DOF.

In most of the situations where I need long DOF, I have plenty of light for base ISO. And then the tables are turned. Now the larger sensor can receive more total light before it saturates, and that means that it will end up with less noise in the final photo.

So in reality, the larger sensor will very often win the noise contest.

This is a very good point.... I came to the same conclusion a while back and forgot. Not too many folks shoot night time landscapes.

There are DoF limits though IMO, even in the dark. I have an FD 50 1.4 and it's really not of much use below F/2.0. It's sharpish at F/2 but only for that sliver of DoF. For wider glass it's not as much of an issue (but then wider glass doesn't get as fast for the most part). And then there are lost resolution issues due to vignetting.

First of all, correct me if I'm wrong, but sensitivity across formats is not really equivalent, and smaller sensors are inherently more sensitive than larger sensors for a given DoF & shutter speed length. I.e. if you have the same ISO, aperture diameter & shutter speed in front of two different size sensors, the larger sensor will have a dimmer exposure due to the given volume of light being spread over a larger area.

With that in mind, FF has 1.2 stops/2.36 times more sensor area than APS-C. So correct me if I'm wrong, but if an APS-C sensor is rated at ISO1000 for some low light S/N metric, a FF sensor with equivalent performance per unit of area will be rated at ISO2360 for the same metric, correct?

Correct. But the A7 does not have the same area performance as the a6000. And that is the main problem with your comparison: The A7 does not have typical FF performance.

Sony's first three cameras with OSPDAF - a99, NEX-6 and A7 - did all have worse low light performance than comparable non-OSPDAF cameras with Sony sensors, even when compensating for the SLT mirror in the a99. I have never seen a good reason for this, but it is quite clear when you compare DxO numbers. With the a6000, Sony seems to have made an OSPDAF sensor without this OSPDAF penalty.

So if you compare the a6000 to any other newer FF camera with Sony sensor and redo your math, you will see that you get roughly the same noise at the same DOF. The a6000 will not have a noise advantage. (But it will have a DR disadvantage in good light.)

The disadvantage is still there, but it is slight to the point it's negligible. For example the A7r still doesn't break ISO3000 for that 30dB test, while a FF sensor truly equivalent to the A6000 would be ISO3100.

 

[sportyaccordy]

5) stop trolling.

I take offense to this.

More importantly though, if I'm trolling, how does your posting help? You don't have to do this.