Still Confused? I asked this question several weeks ago, but I am still confused about ISO performance. I am comparing Camera A to Camera B. In one of the criterion that was rated, ISO...

leftyD500 Loc: Ocala, Florida

I asked this question several weeks ago, but I am still confused about ISO performance. I am comparing Camera A to Camera B. In one of the criterion that was rated, ISO performance, it stated one reason to choose Camera A over Camera b is: low light ISO Camera A 2956 to Camera B 1324 better high ISO performance. Are they saying that Camera A will focus better in low light? Are they saying that at any given high ISO, Camera A will have less noise than Camera B? Exactly what should I be understanding about this? Please help this ISO challenged old man.

jaymatt Loc: Alexandria, Indiana

My advice: buy the one you like better and forget the techno data.

Longshadow Loc: Audubon, PA, United States

jaymatt wrote:

My advice: buy the one you like better and forget the techno data.

My camera uses ISO, I have it set to the native value, no auto.

Higher ISO, more light sensitivity, as well as more resultant noise.
Lower ISO, less light sensitivity, as well as less resultant noise.

SonyA580 Loc: FL in the winter & MN in the summer

Perhaps if you mention the names and model numbers of the 2 cameras it would be possible for someone who actually owns them to comment on the relative performance of each under low and high ISO conditions.

BebuLamar

jradose wrote:

I asked this question several weeks ago, but I am ... (show quote)

You mean the DxO score? They meant camera A has less noise than camera B at high ISO.
However if camera B has significantly higher resolution you can resize the image to the same resolution as camera A and have less noise.

leftyD500 Loc: Ocala, Florida

SonyA580 wrote:

Perhaps if you mention the names and model numbers of the 2 cameras it would be possible for someone who actually owns them to comment on the relative performance of each under low and high ISO conditions.

Camera A would be the Nikon D750, Camera B would be the Nikon D500. I understand how ISO works, I am just confused as to what they actually mean by "better high ISO performance." Perhaps I am thinking too deeply.

Ysarex Loc: St. Louis

jradose wrote:

I asked this question several weeks ago, but I am ... (show quote)

Those are DXOMark test scores. They tell you what they mean: https://www.dxomark.com/dxomark-camera-sensor-testing-protocol-and-scores/

They are talking about noise which they measure as SNR (signal to noise ratio). From the link above: "To compensate for the lack of exposure, photographers have to increase the ISO setting, which results in a decreased signal-to-noise ratio (SNR). How far can ISO be increased while maintaining decent image quality? The DxOMark low-light ISO metric will give you this information.

The SNR indicates how much noise is present in an image compared to the actual image information (signal). The higher the SNR value, the better the image quality, as detail is not drowned out by noise. The SNR is given in dB, which is a logarithmic scale: an increase of 6 dB corresponds to doubling the SNR, which in turn equates to half the noise for the same signal. A SNR value of 30dB means excellent image quality. We have therefore defined low-light ISO as the highest ISO setting for a camera that allows it to achieve a SNR of 30dB while keeping a good dynamic range of 9 EVs and a color depth of 18bits. A difference in low-light ISO of 25% equals 1/3 EV and is only slightly noticeable."

So the higher the number you're referencing the better the camera's low-light performance (less noise).

Longshadow Loc: Audubon, PA, United States

jradose wrote:

Camera A would be the Nikon D750, Camera B would be the Nikon D500. I understand how ISO works, I am just confused as to what they actually mean by "better high ISO performance." Perhaps I am thinking too deeply.

Less noise at a higher ISO.
Matters to some people if they shoot high ISO.

Ysarex Loc: St. Louis

jradose wrote:

Camera A would be the Nikon D750, Camera B would be the Nikon D500. I understand how ISO works, I am just confused as to what they actually mean by "better high ISO performance." Perhaps I am thinking too deeply.

Used to take the same photo at the same high ISO value you'll see less visible noise from the D750 (higher score) than the D500 (lower score). The difference is expected if only due to the different size sensors in those two cameras: larger sensor = less noise all else equal.

Picture Taker Loc: Michigan Thumb

I think your approach of camera A and B are throwing us off. We might be able to help with the knowledge of each camera. Unless this is a theoretical question.
Please respond to the questions.

leftyD500 Loc: Ocala, Florida

Picture Taker wrote:

I think your approach of camera A and B are throwing us off. We might be able to help with the knowledge of each camera. Unless this is a theoretical question.
Please respond to the questions.

I did in a later reply: CAmera A is D750 and Camera B is D500.

SuperflyTNT Loc: Manassas VA

jradose wrote:

Camera A would be the Nikon D750, Camera B would be the Nikon D500. I understand how ISO works, I am just confused as to what they actually mean by "better high ISO performance." Perhaps I am thinking too deeply.

Given the relative “vintage” of those cameras and resolution I would expect the full frame sensor to be better at high ISO than the APS-C sensor, but I would also guess that the D500 would focus better in low light.

R.G. Loc: Scotland

If it's DXO scores you're talking about, this page explains their scoring system. In particular, concerning ISO, in the section sub-headed "Sports & action score: Low-Light ISO" they say -

"The SNR (signal-to-noise ratio) indicates how much noise is present in an image compared to the actual image information (signal). The higher the SNR value, the better the image quality, as detail is not drowned out by noise.... A SNR value of 30dB means excellent image quality. We have therefore defined low-light ISO as the highest ISO setting for a camera that allows it to achieve a SNR of 30dB while keeping a good dynamic range of 9 EVs and a color depth of 18bits.....".

As this explanation indicates, high ISOs can cause the detail to be "drowned out by noise". But before that happens, noise has the potential to significantly degrade the image quality. A signal-to-noise ratio (SNR) of 30dB is used as their reference point since it indicates that the camera will produce good image quality at that level. As you raise the ISO value the SNR falls - a good camera will produce a good SNR (i.e. not much noise) at high ISOs.

Bill_de Loc: US

jradose wrote:

Camera A would be the Nikon D750, Camera B would be the Nikon D500. I understand how ISO works, I am just confused as to what they actually mean by "better high ISO performance." Perhaps I am thinking too deeply.

Typically the larger the photosite, the less noise it generates. Squeeze 20 mp into a smaller space you get smaller photosites. The 'noise' generated degrades the image.

A larger photosite size has less noise fundamentally because the accuracy of the measurement from a sensor is proportional to the amount of light it collects.

https://pixelcraft.photo.blog/2020/04/13/photosite-size-and-noise/

You might want to learn some Google skills. You will find more in depth answers than most answers on any forum.

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jeep_daddy Loc: Prescott AZ

jradose wrote:

I asked this question several weeks ago, but I am ... (show quote)

Better low light performance means that the camera will:
!. have less noise at the higher ISO settings
2. early in the morning or very late in the day when the light is low, you can crank up the ISO so that you can use a faster shutter to capture the subject without it being blurry. This comes in handy for those that like to take pictures of wildlife because much wildlife can be seen at those times of day, but if the camera has poor ISO performance, the picture will be very "noisy" if you crank up the ISO to achieve that fast shutter to stop motion blur.