Isomeric octopus pigment analogues from 9-cis and 11-cis 10-fluoro retinal have been prepared and their photochemical as well as other properties examined. While most of the properties of the fluorinated analogues remained similar to those of the parent system, the following differences were noted. Fluorine substitution at the 10-position increased the UV opsin shift (UV OS) values of the pigments and increased the fluorine opsin shift (FOS) compared to that in bovine rhodopsin. For the 9-cis 10-fluoro octopus pigment, a reduction in photosensitivity and in FOS were observed compared to that in bovine rhodopsin. These results suggest that in octopus rhodopsin the environment around the fluorine probe in the 11-cis chromophore is more sterically hindered compared to that in bovine, while the opposite is likely for the 9-cis.