http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_of_light.html Steve Carlip: "To state that the speed of light is independent of the velocity of the observer is very counterintuitive. Some people even refuse to accept this as a logically consistent possibility, but in 1905 Einstein was able to show that it is perfectly consistent if you are prepared to give up assumptions about the absolute nature of space and time."
Procrusteanizing space and time in conformity with a "very counterintuitive" statement is insane of course but that insanity is not enough. In the following video the observer starts moving away from the light source with speed v and sane people see the frequency shift from f to f'=(c-v)/L and the speed of the light waves (relative to the observer) shift from c to c'=c-v. Sane people neither see nor can imagine the wavelength, L, varying with the speed of the moving observer. Dr. Ricardo Eusebi and Einsteinians all over the world agree that the frequency shifts from f to f'=(c-v)/L but, unlike sane people, they see the wavelength shift from L to L'=cL/(c-v) so that the speed of the light waves relative to the observer can gloriously remain constant, c'=f'L'=c, Divine Einstein, yes we all believe in relativity, relativity, relativity: