If the observer stands on the surface of a celestial body with a substantial gravitational field, or if, in the absence of a gravitational field, the observer accelerates towards the emitter, then he finds the frequency of coming light INCREASING, and this is experimentally confirmed. The above formula allows two (incompatible) implications:
1. The wavelength is constant while the speed of light increases with the frequency. This is fatal for Einstein's relativity and, if a prophesy made by Einstein in 1954 is taken seriously, for contemporary physics as a whole.
2. The speed of light is constant while the wavelength decreases with the frequency. This contradicts Einstein's general relativity where the speed of light in a gravitational field is VARIABLE; moreover, there can be nothing sillier than a wavelength varying with the speed of the observer:
http://sampit.geol.sc.edu/Doppler.html
"Moving observer: A man is standing on the beach, watching the tide. The waves are washing into the shore and over his feet with a constant frequency and wavelength. However, if he begins walking out into the ocean, the waves will begin hitting him more frequently, leading him to perceive that the wavelength of the waves has decreased."
http://www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/big_bang/index.html
John Norton: "Here's a light wave and an observer. If the observer were to hurry towards the source of the light, the observer would now pass wavecrests more frequently than the resting observer. That would mean that moving observer would find the frequency of the light to have increased (AND CORRESPONDINGLY FOR THE WAVELENGTH - THE DISTANCE BETWEEN CRESTS - TO HAVE DECREASED)."