D600 High ISO in DX

Started Nov 23, 2012 | Questions
Jeroniemo
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D600 High ISO in DX
Nov 23, 2012

When a DX lens is used on the D600, will you get better high ISo performance than the say D5200 ?

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Jeroniemo

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3D Gunner
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Re: D600 High ISO in DX
In reply to Jeroniemo, Nov 23, 2012

The ISO performance is the same as in FX mode, only the image is cropped at ~10MP in DX mode. The type of lens used have nothing to do with ISO performance.

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clarnibass
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Re: D600 High ISO in DX
In reply to Jeroniemo, Nov 23, 2012

The D5200 isn't out yet AFAIK but you can get an approximate comparison by using DPR's samples. Go to the studio comparison tool and choose the D600 and also the camera you want to compare it with. Download the files (I would use the RAW versions). Reduce the other camera to approx 4000 x 2667 size. The frame of the two photos isn't the same but the noise per area is what you would get. I assume you are interested in noise for the same frame/size.

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John Motts
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Re: D600 High ISO in DX
In reply to 3D Gunner, Nov 23, 2012

3D Gunner wrote:

The ISO performance is the same as in FX mode, only the image is cropped at ~10MP in DX mode. The type of lens used have nothing to do with ISO performance.

The ISO performance is a lot worse than in FX mode.

For example the degree of grain on a 12x8 print in DX mode would be similar to what you would see on a 18x12 in FX mode.

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Leo360
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Re: D600 High ISO in DX
In reply to Jeroniemo, Nov 23, 2012

Jeroniemo wrote:

When a DX lens is used on the D600, will you get better high ISo performance than the say D5200 ?

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Jeroniemo

ISO performance in D600 DX crop mode should be the same a in D600 FX mode. At this point comparing to D5200 is purely speculative, for I have no any hard data. But one typically expects FX body to perform better. D600 photosites are 6x6 microns while D5200 are 4x4 microns. So geometry is on the D600 side

Leo

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3D Gunner
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Re: D600 High ISO in DX
In reply to John Motts, Nov 23, 2012

That depends on your point of view. The relation noise to signal at pixel level is the same in FX and DX.

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Leo360
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Re: D600 High ISO in DX
In reply to 3D Gunner, Nov 23, 2012

3D Gunner wrote:

That depends on your point of view. The relation noise to signal at pixel level is the same in FX and DX.

He is asking about D600 DX crop mode and D5200. Between two different cameras SNR is not the same.

Leo

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3D Gunner
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Re: D600 High ISO in DX
In reply to Leo360, Nov 23, 2012

I am talking about SNR in FX vs DX in D600 camera.

The initial question is confusing, but in short, with the same DX lens is better to take the picture at 24 MP with D3200 or D5200 than with D600 at 10MP in DX mode.

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John Motts
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Re: D600 High ISO in DX
In reply to 3D Gunner, Nov 23, 2012

3D Gunner wrote:

That depends on your point of view. The relation noise to signal at pixel level is the same in FX and DX.

..which in practice means nothing.

I'm talking about actually reproducing and using the files.

If you only use half of the sensor or half of the image, then you have to enlarge your image twice as much, just as you would do with different film formats.

So beyond any question, the high ISO performance is always going to be better when you use all of the sensor rather than just half of it. "Pixel level" is meaningless in practice.

In answer to the OP, we don't actually know about the D5200 yet. Sorry.

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bobn2
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Re: D600 High ISO in DX
In reply to Leo360, Nov 23, 2012

Leo360 wrote:

Jeroniemo wrote:

When a DX lens is used on the D600, will you get better high ISo performance than the say D5200 ?

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Jeroniemo

ISO performance in D600 DX crop mode should be the same a in D600 FX mode.

No it shouldn't. The DX sensor, or DX crop form a sensor will be collecting over a stop less light than an FX sensor. If we assume that The D5200 sensor has the same efficiency as the D600 sensor, then the 'ISO performance' (there is no such thing, actually) of it and a DX crop from a D600 will be exactly the same. The D5200 will reveal more detail, since it has 24MP as opposed to 10.5.

At this point comparing to D5200 is purely speculative, for I have no any hard data. But one typically expects FX body to perform better. D600 photosites are 6x6 microns while D5200 are 4x4 microns. So geometry is on the D600 side

Photosite (or even pixel) size has very little connection to sensor efficiency and therefore low light performance. The pixels might be bigger, but you have fewer of them, so in the end the same amount of light gets collected.

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Bob

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3D Gunner
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Re: D600 High ISO in DX
In reply to John Motts, Nov 23, 2012

John Motts wrote:

3D Gunner wrote:

That depends on your point of view. The relation noise to signal at pixel level is the same in FX and DX.

..which in practice means nothing.

I'm talking about actually reproducing and using the files.

If you only use half of the sensor or half of the image, then you have to enlarge your image twice as much, just as you would do with different film formats.

So beyond any question, the high ISO performance is always going to be better when you use all of the sensor rather than just half of it. "Pixel level" is meaningless in practice.

In answer to the OP, we don't actually know about the D5200 yet. Sorry.

All you said is very correct, but in the question is mentioned only "DX lens", not also the DX format. You can use a DX lens on FX format if you want, with more or less vignetting, depending on the type of lens. This will require more or less later crop.

By example, Nikon 35mm f1.8 DX has FX coverage and in video mode will give much better results on D600 FX format than in all other DX cameras.

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John Motts
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Re: D600 High ISO in DX
In reply to 3D Gunner, Nov 23, 2012

3D Gunner wrote:

John Motts wrote:

3D Gunner wrote:

That depends on your point of view. The relation noise to signal at pixel level is the same in FX and DX.

..which in practice means nothing.

I'm talking about actually reproducing and using the files.

If you only use half of the sensor or half of the image, then you have to enlarge your image twice as much, just as you would do with different film formats.

So beyond any question, the high ISO performance is always going to be better when you use all of the sensor rather than just half of it. "Pixel level" is meaningless in practice.

In answer to the OP, we don't actually know about the D5200 yet. Sorry.

All you said is very correct, but in the question is mentioned only "DX lens", not also the DX format. You can use a DX lens on FX format if you want, with more or less vignetting, depending on the type of lens. This will require more or less later crop.

Yes, but I was replying to your comments about DX vs FX.

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5tve
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Re: D600 High ISO in DX
In reply to Jeroniemo, Nov 23, 2012

Check out B Claff's excellent ISO versus Dynamic Range chart

http://home.comcast.net/~NikonD70/Charts/PDR.htm

The D600 has two entries  FX & DX

 5tve's gear list:5tve's gear list
Nikon D7000 Sony a6000
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Leo360
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pixel pitch and SNR
In reply to bobn2, Nov 23, 2012

bobn2 wrote:

Photosite (or even pixel) size has very little connection to sensor efficiency and therefore low light performance. The pixels might be bigger, but you have fewer of them, so in the end the same amount of light gets collected.

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Bob

There are two different things here. There is photon count per pixel and number of photons collected per unit area. The latter does not depend on the pixel pitch but the former does. And SNR per pixel gets larger with more photons collected by that pixel (photon shot-noise per photon gets weaker). For the same exposure larger pixels capture more photos and, thus, have higher SNR. This is why pixel peeping reveals more noise-per-pixel for smaller photosites. The price to pay is reduced resolution. With proper down-sampling (bicubic, etc) to the same level of detail one can hope to recover the SNR back by effectively combining outputs of multiple smaller pixels into an aggregate one but doing so does not entirely compensate for read-noise increase.

Correct me if I am wrong, but I think that you will have to jump through several hoops to match 4x4 um pixel SNR to 6x6 um one.

Leo

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Leo360
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Re: pixel pitch and SNR
In reply to Leo360, Nov 23, 2012

Leo360 wrote:

bobn2 wrote:

Photosite (or even pixel) size has very little connection to sensor efficiency and therefore low light performance. The pixels might be bigger, but you have fewer of them, so in the end the same amount of light gets collected.

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Bob

There are two different things here. There is photon count per pixel and number of photons collected per unit area. The latter does not depend on the pixel pitch but the former does. And SNR per pixel gets larger with more photons collected by that pixel (photon shot-noise per photon gets weaker). For the same exposure larger pixels capture more photos and, thus, have higher SNR. This is why pixel peeping reveals more noise-per-pixel for smaller photosites. The price to pay is reduced resolution. With proper down-sampling (bicubic, etc) to the same level of detail one can hope to recover the SNR back by effectively combining outputs of multiple smaller pixels into an aggregate one but doing so does not entirely compensate for read-noise increase.

Correct me if I am wrong, but I think that you will have to jump through several hoops to match 4x4 um pixel SNR to 6x6 um one.

Leo

Bill Claff does not have D5200 numbers yet but comparing D600 (DX) to D7000 (or D5100 for that matter)

http://home.comcast.net/~NikonD70/Charts/PDR.htm

shows that D600(DX) has about 1/4 stop advantage over D7000. Of course, these numbers are Expeed 3 versus Expeed 2. But D5200 will have even smaller photosites. Waiting to see how it all plays out.

Leo

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John Motts
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Re: pixel pitch and SNR
In reply to Leo360, Nov 23, 2012

Leo360 wrote:

bobn2 wrote:

Photosite (or even pixel) size has very little connection to sensor efficiency and therefore low light performance. The pixels might be bigger, but you have fewer of them, so in the end the same amount of light gets collected.

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Bob

There are two different things here. There is photon count per pixel and number of photons collected per unit area. The latter does not depend on the pixel pitch but the former does. And SNR per pixel gets larger with more photons collected by that pixel (photon shot-noise per photon gets weaker). For the same exposure larger pixels capture more photos and, thus, have higher SNR. This is why pixel peeping reveals more noise-per-pixel for smaller photosites. The price to pay is reduced resolution. With proper down-sampling (bicubic, etc) to the same level of detail one can hope to recover the SNR back by effectively combining outputs of multiple smaller pixels into an aggregate one but doing so does not entirely compensate for read-noise increase.

Correct me if I am wrong, but I think that you will have to jump through several hoops to match 4x4 um pixel SNR to 6x6 um one.

Leo

Doesn't anyone use their eyes anymore? 

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noirdesir
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Re: pixel pitch and SNR
In reply to Leo360, Nov 23, 2012

Leo360 wrote:

bobn2 wrote:

Photosite (or even pixel) size has very little connection to sensor efficiency and therefore low light performance. The pixels might be bigger, but you have fewer of them, so in the end the same amount of light gets collected.

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Bob

There are two different things here. There is photon count per pixel and number of photons collected per unit area. The latter does not depend on the pixel pitch but the former does. And SNR per pixel gets larger with more photons collected by that pixel (photon shot-noise per photon gets weaker). For the same exposure larger pixels capture more photos and, thus, have higher SNR. This is why pixel peeping reveals more noise-per-pixel for smaller photosites. The price to pay is reduced resolution.

With proper down-sampling (bicubic, etc) to the same level of detail one does can hope to recover the SNR back by effectively combining outputs of multiple smaller pixels into an aggregate one but doing so does not entirely compensate for read-noise increase.

The photon shot noise per sensor area will be exactly the same for both the smaller and the larger pixel sensors, assuming the same quantum efficiency.

And the read noise component of the final noise usually is the same or even lower for smaller pixels because noise is not something that gets simply summed up as it is a standard deviation.

In an ideal world, read noise is proportional to pixel size. So, let's take a 2x2 μm pixel with a read noise of 6 e- (ie, a standard deviation of 6 e-). Now compare that to a 2x2 pixel array of 1x1 μm pixels, where each pixel has a read noise of 1.5 e-. Simple statistics tell us that the read noise component for a combination of these four smaller pixels is:

rn(com) = square root of (1.5^2 + 1.5^2 + 1.5^2 + 1.5^2) = 3 e-

ie, lower than that of the sensor with larger pixels. Of course, whether the smaller pixels achieve a read noise reduction proportional to their area depends on how the pixel size reduction is achieved but if it is through a process shrink, you can actually have less noise in your final image with smaller pixels (all else equal, ie, sensor size and QE).

Take a real-life example, the Nikon D600 and D800 which have sensors of pretty much the same generation from the same design team (Sony) using more or less the same design goals and philosophies. Read noise numbers vary a bit over the ISO settings but if we omit the highest and lowest ISO setting we get an average of 3.74 e- for the D600 and 3.1 e- for the D800. And if we round the pixel size a little bit three D800 pixels cover the same area as two D600 pixels. Thus:

rn(D800) = square root of (3.1^2 + 3.1^2 + 3.1^2) = 5.37 e-

rn(D600) = square root of (3.74^2 + 3.74^2) = 5.29 e-

That is essentially a draw. But if we compare this with the D3x we get 5.80 e-, so going from the D3x to the D800 we achieved less read noise per sensor area while having smaller pixels. If we go one step further and look at the Olympus OM-D E-M5 (which is widely assumed to have a Sony sensor as well), read noise 2.62 e- per pixel, we get (for more instructive comparions we take 63 D800 pixels and 100 E-M5 pixels):

rn(D800) = 29.7 e- and rn(E-M5) = 26.2 e-, a small but measurable difference in favour of the smaller pixels.

(All read noise values from sensorgen.info)

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noirdesir
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Re: pixel pitch and SNR
In reply to John Motts, Nov 23, 2012

John Motts wrote:

Leo360 wrote:

bobn2 wrote:

Photosite (or even pixel) size has very little connection to sensor efficiency and therefore low light performance. The pixels might be bigger, but you have fewer of them, so in the end the same amount of light gets collected.

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Bob

There are two different things here. There is photon count per pixel and number of photons collected per unit area. The latter does not depend on the pixel pitch but the former does. And SNR per pixel gets larger with more photons collected by that pixel (photon shot-noise per photon gets weaker). For the same exposure larger pixels capture more photos and, thus, have higher SNR. This is why pixel peeping reveals more noise-per-pixel for smaller photosites. The price to pay is reduced resolution. With proper down-sampling (bicubic, etc) to the same level of detail one can hope to recover the SNR back by effectively combining outputs of multiple smaller pixels into an aggregate one but doing so does not entirely compensate for read-noise increase.

Correct me if I am wrong, but I think that you will have to jump through several hoops to match 4x4 um pixel SNR to 6x6 um one.

Leo

Doesn't anyone use their eyes anymore?

When you buy tomatoes, to 'weigh' them with your hands to figure out which box contains more or do you put them on a balance? If something can be done faster and more accurately with the help of technology, it is usually more sensible to use the technology.

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John Motts
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Re: pixel pitch and SNR
In reply to noirdesir, Nov 23, 2012

noirdesir wrote:

John Motts wrote:

Leo360 wrote:

bobn2 wrote:

Photosite (or even pixel) size has very little connection to sensor efficiency and therefore low light performance. The pixels might be bigger, but you have fewer of them, so in the end the same amount of light gets collected.

-- hide signature --

Bob

There are two different things here. There is photon count per pixel and number of photons collected per unit area. The latter does not depend on the pixel pitch but the former does. And SNR per pixel gets larger with more photons collected by that pixel (photon shot-noise per photon gets weaker). For the same exposure larger pixels capture more photos and, thus, have higher SNR. This is why pixel peeping reveals more noise-per-pixel for smaller photosites. The price to pay is reduced resolution. With proper down-sampling (bicubic, etc) to the same level of detail one can hope to recover the SNR back by effectively combining outputs of multiple smaller pixels into an aggregate one but doing so does not entirely compensate for read-noise increase.

Correct me if I am wrong, but I think that you will have to jump through several hoops to match 4x4 um pixel SNR to 6x6 um one.

Leo

Doesn't anyone use their eyes anymore?

When you buy tomatoes, to 'weigh' them with your hands to figure out which box contains more or do you put them on a balance? If something can be done faster and more accurately with the help of technology, it is usually more sensible to use the technology.

Simple statistics tell us that the read noise component for a combination of these four smaller pixels is: rn(com) = square root of (1.5^2 + 1.5^2 + 1.5^2 + 1.5^2) = 3 e-

Fair comment, but everyone knows how to use scales.

However it's a good deal more straightforward to just compare images with your eyes than to go into this technical depth that leaves most people in the dark. Your "simple" statistics quoted above for example.

There are people coming in to photography who read all the techno stuff but still haven't got a clue about the most basic concepts.

Photography is getting unnecessarily complex and it is this that leads to the most unbelievable misunderstandings of quite basic photographic concepts that we so often see on these forums.

Very little of this techno stuff is essential to produce good photography and is more relevant to camera design rather than camera use.

I don't wish to take anything away from your technical knowledge and it's great if you're interested in that area, but it's specialist stuff and it's a shame if we lose sight of photography itself.

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Leo360
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Re: pixel pitch and SNR
In reply to noirdesir, Nov 23, 2012

noirdesir wrote:


Leo360 wrote:

There are two different things here. There is photon count per pixel and number of photons collected per unit area. The latter does not depend on the pixel pitch but the former does. And SNR per pixel gets larger with more photons collected by that pixel (photon shot-noise per photon gets weaker). For the same exposure larger pixels capture more photos and, thus, have higher SNR. This is why pixel peeping reveals more noise-per-pixel for smaller photosites. The price to pay is reduced resolution.

With proper down-sampling (bicubic, etc) to the same level of detail one does can hope to recover the SNR back by effectively combining outputs of multiple smaller pixels into an aggregate one but doing so does not entirely compensate for read-noise increase.

The photon shot noise per sensor area will be exactly the same for both the smaller and the larger pixel sensors, assuming the same quantum efficiency.

Yes, per unit area photon count and photon shot noise are the same. But measured per pixel the photon count as well as photon shot-noise variance are proportional to the pixel area (assuming constant fill factor).

And the read noise component of the final noise usually is the same or even lower for smaller pixels because noise is not something that gets simply summed up as it is a standard deviation.

If your noise sources are uncorrelated you sum up noise variances (squares of std.dev.)

In an ideal world, read noise is proportional to pixel size.

Why is that? I think that in ideal world read-noise should be independent of pixel size and should only depend on the temperature (even ideal world has thermal noise).

So, let's take a 2x2 μm pixel with a read noise of 6 e- (ie, a standard deviation of 6 e-). Now compare that to a 2x2 pixel array of 1x1 μm pixels, where each pixel has a read noise of 1.5 e-.

I don't think so. What makes you think that read-noise std.dev. scales quadratic with pixel pitch. Please, provide some rational for this behavior.

Simple statistics tell us that the read noise component for a combination of these four smaller pixels is:

rn(com) = square root of (1.5^2 + 1.5^2 + 1.5^2 + 1.5^2) = 3 e-

The formula above is based on a questionable assumption. Following your line of thoughts I will consider 2x2 um pixel against a group of 100 of 0.2x0.2 um pixels with the read-noise sigma= 0.06. This follows from your own read-noise scaling rule! Now based on your summation formula I will conclude that

rn = 10x0.06 = 0.6 which is 10 times smaller that original 2x2 pixel.

After signal aggregation from all 100 micro-pixels the 2x2 pixel SNR increased 10 times. Seems too good to be true or is it?

There is also dark current which neither of us have considered.

Bottom line, sensor noise performance is messy and contains lots of proprietary stuff in processing chain that we are not privy to.

So far from what I saw on Bill Claff's charts is that D600(DX mode) dynamic range outperforms  D7000 at all ISOs. I have no reason to think that with D5200 it will be any different.

Leo

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