The plural of photographer is photographers.
The reason is because the word is derived from Ancient Greek. For Greek words ending in a f remains the f also stand in plural.
Photographer comes from the Greek word φωτογράφος (fotográfos). The word photographer means "Those who write with light"
- Light, φως (fós)
- Writing, γράφω (grápso)
How a photographer writes with light:
A photographer writes with light using existing light or flash. In doing so, the photographer can adjust the light sensitivity of the negative or sensor. The throughput of light can be limited by the aperture and the duration of light can be determined by means of the shutter.