Le Gray shot directly into the sun for this photograph in an attempt to balance on one glass negative the exposure for a bright sky and a relatively dark sea. The sun has become a dark disc owing to a photochemical phenomenon in which extreme overexposure at an intense point of light reverses the tones on the negative.

Collodion-on-glass negatives were introduced in 1851. Le Gray adopted them in preference to paper negatives to achieve maximum sharpness coupled with even faster exposure times. The glass plate was covered with a solution of ether and guncotton (cotton steeped in nitric and sulphuric acids). It was then sensitised. The negative had to be exposed in the camera while still wet and developed immediately afterwards.