Question

The green arrow points to a mark on a DSLR camera body. What does this mark represent?

• A. Infinity Focus
• B. Closed Aperture
• C. Focal Plane
• D. Firmware Reset

Hint:

Remember: the “circle with a line” mark on a camera body is the focal-plane index. Measure subject distance to that mark—not to the front of the lens—when absolute accuracy is needed.

Answer 1

The Correct Option is C

The symbol is a small circle with a short horizontal line through it. On cameras this denotes the film/sensor focal plane—the exact plane where the image is formed on the sensor (or film). It serves as the reference point for precise focus-distance measurements (e.g., when focusing by measured subject distance or for macro/cinema work).
It is not an infinity-focus indicator (A), has nothing to do with aperture state (B), and is unrelated to firmware (D). Therefore the correct choice is 
(C) Focal Plane.