Science Buddies: "Ask an Expert"

I'm halfway through my experiment. Followed the draft plan from science buddies on digital photos and dynamic range. But i'm getting quite confused now. I'm done with taking pictures, (I took shots with 14 different shutter speeds with constant factors of ISO and aperture 4 times) done with analyzing the pictures ( all of them). my questions are:
1) i understand i'll make a graph to show results with the shutter speeds as the x axis. do i take the min.+ mean.+ mode.+ max. + Std. Dev. and get an average of all? Isn't that why we are told to collect all this data and take note of them on a table?

2) what dose the short-form Std. Dev. stand for?

this is my table so far:
Shutter Speed Pixel Gray Level Statistics
Mean Std. Dev. Min Max Mode File Name
8 253.00 0.038 216 255 253 IMG_3088
4 253.000 0.035 216 255 253 IMG_3096
2 253.000 0.031 216 255 253 IMG_3100
1 253.000 0.026 219 255 253 IMG_3013
1/2 253.000 0.013 232 255 253 IMG_3108
1/4 244.214 198.83 187 251 245 IMG_3110
1/8 196.310 3.166 148 221 198 IMG_3113
1/15 147.417 3.692 103 208 148 IMG_3118
1/30 114.035 4.581 56 195 115 IMG_3122
1/60 74.678 5.752 21 163 75 IMG_3127
1/125 26.949 4.377 1 150 27 IMG_3133
1/500 18.520 4.029 0 141 18 IMG_3135
1/500 6.657 3.002 0 136 6 IMG_3140
1/1000 3.046 2.257 0 138 2 IMG_3144

Lets forget about more complicated math for a moment and just think about MIN and MAX and what they mean in a digital JPEG image with 8 bit resolution. A MIN of 0 in an image means there was at least one pixel that did not register any light so we don't know how dark it(they) really was(were), there is just something darker than what the camera can measure at that setting. A MAX of 255 in an 8 bit JPEG image means there was at least one pixel that was brighter than what the camera could measure at that setting. All 8 bit JPEG images with either a 0 or a 255 in a pixel means that the image exceeded the dynamic range of the camera at the setting it was taken. The only thing that we can learn from these images wrt dynamic range is that it was greater than what the camera could render at the setting involved. The more interesting results are the images where all pixels are within the dynamic range of the camera.

Given that you are only presenting what appears to be one set of numbers instead of separate Red/Green/Blue numbers, I'm assuming you took the pictures in black and white mode. If not, then you need to be dealing with each color channel separately wrt dynamic range.

Now for some more complicated math (but restricted to cases where the image was within the dynamic range). When the MEAN (midpoint between MIN and MAX values) and the AVERAGE (sum of all pixel values divided by number of values or pixels for a given color channel or black and white composite) differ considerably, we know that the distribution of the pixel values in the histogram is not very uniform over the dynamic range (MIN to MAX). The STANDARD DEVIATION is a better measure of the uniformity of the pixel values. It adds up the square of the deviation of each pixel value from the AVERAGE and divides by the number of pixel values. The smaller this standardized deviation is, the more uniform the pixel values are spread from MIN to MAX. This can be seen in the histogram view of the camera.

Now for what you want to graph. You need to go back to your hypothesis. What is it that you are trying to prove or disprove? What mathmatical representation is most effective at demonstrating how well your hypothesis conforms to your test results? What mathmatical values or tests then confirm that the your demonstration variables are valid?

in contrast to other experiments i've done this one dosen't have a hypothesis....the experiment was to find out the dynamic range of my camera. OK now with all this data...seems like i've hit a rock....i don't know how to make that sample graph with my results and determine my camera's dynamic range?
https://www.sciencebuddies.org/science- ... ?from=Home
as in step 5 of the experiment.