aryagoel1
Part 1 - Image 2 (f/10)
The lens used is a Canon EFS 18-135mm Marco Lens. The focal length of the image is 71mm with aperture of f/10.0. So N = 10.0 and f = 71. The camera shot is 600mm (60 cm) from the subject at focus, so U = 600. The only remaining variable is the size of the circle of confusion which for my camera was 0.02, C = 0.02.
Therefore, plugging the information into the formula gives me: (2CNU^2)/(f^2) = (2(0.02)(10.0)(600)^2)/(71^2)
= 28.6 mm is the expected DOF when ruler is horizontal.
However, the ruler is foreshortened, because it's at an angle of 45 degrees. 28.6 mm of depth being in focus should mean a space of sqrt(2)*28.6 mm on the ruler looks sharp. Sqrt(2)*28.6 = 40.4 mm.
Looking at the image, I would say it's in focus between the 13.5 cm mark and the 17.5 cm mark. That's 40 mm, which is pretty close to the calculated value... Success!
Part 1 - Image 2 (f/10)
The lens used is a Canon EFS 18-135mm Marco Lens. The focal length of the image is 71mm with aperture of f/10.0. So N = 10.0 and f = 71. The camera shot is 600mm (60 cm) from the subject at focus, so U = 600. The only remaining variable is the size of the circle of confusion which for my camera was 0.02, C = 0.02.
Therefore, plugging the information into the formula gives me: (2CNU^2)/(f^2) = (2(0.02)(10.0)(600)^2)/(71^2)
= 28.6 mm is the expected DOF when ruler is horizontal.
However, the ruler is foreshortened, because it's at an angle of 45 degrees. 28.6 mm of depth being in focus should mean a space of sqrt(2)*28.6 mm on the ruler looks sharp. Sqrt(2)*28.6 = 40.4 mm.
Looking at the image, I would say it's in focus between the 13.5 cm mark and the 17.5 cm mark. That's 40 mm, which is pretty close to the calculated value... Success!