Science Buddies: "Ask an Expert"

In the project "Digital Photos and Dynamic Range," it tells you as the last step to calculate from your graph the dynamic range. How do I do that? It doesn't say. Thank you!
~Photography_Gurl

Hi Photography_Gurl,

In this project dynamic range refers to the responsiveness of the camera's sensor to light.

A low gray level will result when the shutter opening time is short. If the shutter opening is extremely short the gray level will be zero. So the low end of the dynamic range is the point at which the gray level is zero.

Long shutter openings produce high gray levels. Very long shutter times will max out the gray level. That is the gray level will go no higher even if the shutter time is increased.The high end of the dynamic range is the point at which the gray level reaches its maximum.

If you graphed your data as shown in the example ( https://www.sciencebuddies.org/science- ... #procedure ) you should be able to find the shutter speeds that correspond to the lower and upper ends of the dynamic range. The example graph shows the dynamic range as a green line just above the x-axis. You might use a similar indication of the range on your graph.

Also, you could calculate a ratio of the upper and lower ends of the dynamic range. For example let's say that the sensor began to show a gray level reading at a shutter speed of 0.004 sec. And the sensor gray level maxed out at a shutter speed of 0.5 sec. The ratio (0.5 sec/0.004 sec, or 125:1) is another way to represent the relative responsiveness of the camera sensor.

I hope this helps. Please post again if you have more questions.

A. Norman

Thank you!