leftyD500 Loc: Ocala, Florida

I am one of those people who needs more detailed explanation, so please, help this dummy. In comparing two cameras, I see something like this for ISO performance: Camera A 2980 Camera B 2853, So Camera A has better low light performance. Now, to me, that doesn't satisfy my curiosity. Just how much better is Camera A in taking photos in low light conditions, is it dignificant enough to sway me over to camera A?

BebuLamar

I think you meant the numbers from DxO lab. I don't think other testing labs use the same kind of rating. I think it meant (I may be wrong) that camera A set at ISO 2980 has the same noise as camera B set at ISO 2853 which is little.

CHG_CANON Loc: the Windy City

How high of an ISO do you want to use? At that ISO level, how does your current camera look? Is using a flash a better approach than a new camera?

If the candidate cameras have been out for a while, there will be detailed reviews and example images from ISO-100 through their highest ISO. Compare those examples against each other and against your current camera's results. Look at the 1:1 pixel level details.

Make an informed decision using these freely available resources.

jeep_daddy Loc: Prescott AZ

Your numbers don't make sense because some of your details are missing. Suffice it to say that low light performance simply means that some cameras can have the ISO set much higher than other cameras and produce an image that has less digital noise. People tend to increase the ISO in low light so that the exposure settings will have a fast enough shutter speed to get a photo that doesn't have camera shake blurry images.

One example I can use is I used to own a Canon 7D camera and I used it for wildlife photography. On overcast days I had to increase the ISO to 400 to keep my shutter speed at the very minimum of 1/1000th of a sec. But the images had digital noise that I'd have to get rid of in post processing. I eventually upgraded to the Canon 7D Mk II and the sensor allowed me to go up to ISO 800 with about the same amount of digital noise which allowed my to keep my shutter speed up around 1\2000th of a sec. which was way better for capturing moving birds.

RWR Loc: La Mesa, CA

I would be more interested in which camera has the best long exposure noise reduction.

jeep_daddy Loc: Prescott AZ

I never use it because it will double the length of time an exposure takes. So if you take a 30 sec exposure, the camera won't be ready to take another image for 60 seconds.

BebuLamar

I think the OP meant the numbers listed on DxO lab rating under Sports ( Low light ISO) category.

User ID

Given that whoever invented that scale is almost certainly testing a single sample of each, rather than averaging 5 samples of A and then averaging 5 of B, I find those numbers to be statistically identical ... with absolutely no need to know how the measurement is actually made.

IOW both cameras perform equally in whatever parameter[s] those 4-digit ratings happen to represent.

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If the ratings were based on averaging a properly larger sample size, it would still be true that even on an RMS basis the numbers are so close as to NOT sway a decision maker.

The higher rating is either 4% or 9% higher depending on method. If that is ISO, sharpness, DR, or whatever ... and is derived from testing single samples ... then it falls within production variation margins. Let’s not ignore that lab test instruments and procedures are never 100% consistent. The flipped coin has landed standing up on its edge. Buy either camera.

BebuLamar

Since I am pretty sure that the OP is using the numbers from DxO lab and I have been thinking that DxO lab only test 1 camera of the same model each and not several of them.

Ysarex Loc: St. Louis

dsmeltz Loc: Philadelphia

OK. Again (because this non-specific kind of question is asked over and over and over again), what kind of low light photography? Long exposure of stationary subjects? Concert photography? Astro? It may or may not be significant depending on what EXACTLY you are trying to do.

Ysarex Loc: St. Louis

As BebuLamar noted those are DXOMark ratings. Here's what they say about those numbers:

"When shooting sports or action events, the photographer’s primary objective is to freeze motion, giving priority to short exposure times. 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. Low-light ISO is an open scale." https://www.dxomark.com/dxomark-camera-sensor-testing-protocol-and-scores/

That still leaves a lot of questions about their methodology but, fairly assuming they're consistent in what they do, you can at least use those numbers as side by side comparison values for their tests. In other words DXO assigns a higher value to a camera with better low-light performance on their tests is as much as you can take from them.

Do as Paul suggested and look at real samples from a reviewer like DPreview.

dsmeltz Loc: Philadelphia

Real world trumps DXO every time. They are still measuring static lab conditions. They are not measuring "Sh*t, what is that to my left????" While swinging left to capture a shot. For that you have to seek out what professionals use in those conditions....


Hint it starts with "Ca" and ends with "non". Canon is still the only company out there that thinks field conditions first and lab test results ..... 80th. Ok maybe Canon does not rank those lab results quite that high.
Honestly, if I come to a decision that is so close that I need to look at DXO results, I have to go back and reexamine my whole evaluation.

User ID

Usage is meaningless. The numbers are interchangeable. Concert and Astro are equal in this instance. Likewise for any other uses. Neither camera is better.

SalvageDiver Loc: Huntington Beach CA

I assume you're referring to the DxOMARK Low-Light ISO values. If not, then disregard the rest of this post.

Based on your example, you would not be able to tell the difference between cameras except under laboratory conditions. In general, the higher the LL ISO value, the better. Here is the definition of DxO's LL ISO value.

From DxOMARK, "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. Low-light ISO is an open scale."

More can be read here:
https://www.dxomark.com/dxomark-camera-sensor-testing-protocol-and-scores/

Hope this helps,
Mike