File :-(, x, )
S/Nr Test. Anonymous
Photograph a Kodak 18% grey card with your digital camera following the instructions below.

Camera
Try to shoot with the camera lens focussed at infinity.
Lens focal length is not important.
Integration (exposure) times must be shorter than 1/30 second.
Use an external IR absorbing filter “hot filter” - if available.
Make sure lossy compression (eg. JPG) is NOT used. RAW - TIFF files are preferred.
Balance the camera settings with the subject. (Apply white balance)
Bracket exposures using each “ISO” setting (gain) offered by the camera.
Label the files accordingly (eg. 200…..3,200)
>> NatureGuy !se3A3TwzdY
in before 12% or 18% rage
>> Anonymous
Using Cinepaint, GIMP or PhotoShop
Import the files (TIFF) and select a 64x64 pixel piece of the file representing the grey card.
(- rectangular marquee tool - feather: 0 px - Style: fixed size – Height: 64 px – Width: 64 px)
Select Histogram function and read the data for the selection.
Carefully note down the Mean pixel value and the Standard Deviation for:
Channel RGB, then channels R, G & B separately.
>> Anonymous
Explanation: The mean pixel value represents the Image Signal
The Standard Deviation represents the image Noise
In this situation all pixels (image samples) should have exactly the same number because they were created by exactly the same amount of light. Standard deviation is simply the average difference between a (deviant) pixel value and what it should have been.

Now simply calculate the Signal-to-noise Ratio (S/Nr) by dividing the Mean pixel (S) value by the standard deviation (N) the resulting number is the S/Nr
For example: RGB mean = 109.56 and SD = 1.7
RGB S/Nr = 109.56 divided by 1.7 = S/Nr = 61.93
It’s that simple! Use your computer’s in-built calculator for convenience and carefully record all results for later use.
>> Anonymous
some of them are more like 20+
>> Anonymous
Note at which camera “ISO” gain settings the ISO standard signal-to-noise ratios of 78, 40 and 10 result as these three cut-off values indicate the three image quality standards, “Saturation” “First Excellent” & “First Acceptable”. Remember it is entirely possible that your camera will not achieve the highest “saturation” image quality speed (S/Nr 78) or the lowest “acceptable” (S/Nr 10) image quality speed.

My results for my Canon EOS 400d are - 100iso/66.5,200/69, 400/36.75, 800/25.93 and 1600/17.97
>> Anonymous
Well i guess it's only me who wants to know how their camera performs. I was curious as to how others cameras performed but...
>> des
>>245381
Think of how much you could've accomplished if you spent the time and effort going on a walkabout shooting rather than playing pixelpeep mathmatica...