2024-01-14 Lens Calibration

I had some disappointing results taking puppy portraits inside our house in relatively low light conditions. I used eye detection focusing on my R5 camera with a 35 mm lens at f/4, 1/60 sec, ISO 1600 and between 1 and 1.5 meters distance.

According to the Depth of Field chart below at 1.5 m distance I should get reasonable sharpness about 19 cm in front of the focal plane and 25 cm behind the focal plane. However at 1 m distance that is reduced to 9 cm in front and 10 cm behind the focal plane

The initial result looks OK

However on close inspection the eyes are sharp but the nose is definitely un-sharp.

I decided to test my lens with a calibration tool I built from self adhesive foam core board. Here is the setup.

Focus on the Zero – 35 mm lens, f/4 from 1.5 meter distance, gives disappointing results. At 7 cm in front of, and 9 cm behind the focal plane there is definite fuzziness.

Lesson: Even at f/4, take your images at 1.5 meter or more away from your subject.