How to calculate the shooting distance of SLR camera? For example, I want to shoot a bird at 500 meters.

The shooting distance is the distance from the shooting object to the focal plane, and the sign that a horizontal line passes through the circle on the fuselage indicates the plane position of the focal plane.

The distance you mentioned cannot be calculated and determined. There is a distance mark on the fixed focus head of SLR, but it is usually only marked to more than ten meters, and then it is infinite.

If you want to shoot a bird 500 meters away, you can only aim with a telephoto and then focus quickly. Birds can move, and it's so far away that it's impossible to focus with traps.