
To Test a Len’s Sharpness, you have to secure a piece of newspaper to a wall with scotch tape. After that, illuminate the paper with two high power lights. You need to direct the light to illuminate both sides of the paper. Then, Place your camera on a tripod. You must make the appropriate exposure with the lens auto focus.
Next, open the lens to the widest aperture or the smallest number setting. You should take a picture. Forth, make an exposure for each aperture until the lens is at its smallest opening. Last, Examine the results of each aperture, looking at the sharpness of the center of the frame versus the edge of the frame.








