Science Buddies: "Ask an Expert"

Hello,
I am conducting an experiment for an annual science fair at my school. My project is to make a digital pinhole camera out of a normal digital camera. After, I made the digital pinhole camera I need data to measure the difference between a digital pinhole camera and a digital camera. I need help of knowing how to measure a resolution of a certain picture or how to measure resolution in general. Please help. Thank you.
~Jacob C

Hi ChamplinJ,

Resolution can have a few different meanings in the context of imaging. First, it can refer to the number of pixels a particular sensor has (e.g., a 16 megapixel camera). Second, it can refer to the amount of space covered by a single pixel (e.g., a satellite might take pictures with a resolution of 10 meters per pixel). Third, it can refer to how well one can discriminate between features in an image. These meanings are all related. For your particular project, I suggest taking a picture of the same object, in the same lighting conditions, same camera settings (to the extent possible between the pinhole and normal cameras), and at the same distance. You want the only difference between the two images to be the camera that took the picture. Then, you can compare the two images on your computer screen and comment on which one appears sharper.

Post back if you have other questions.

One of the ways we used to compare the resolution of film camera lenses and film was to use a chart like this: http://students.com.miami.edu/~ed/Forms ... nChart.jpg

You shoot it at a measured distance with the same exposure, but using different lenses or different brands of film, or whatever your independent variable is. You then compare the images. When you can't see the individual black lines any more, that combination of settings/equipment/material can't resolve at that finer resolution. You may be able to come up with some test like that.