I do not know if this will work, I will look into it, thank you. Hyperphysics seems to be pretty trusty right? Not to ask another question before I try your solution but just to firm things up, I am looking into a hypothetical question(which I know do not always have answers :) ). The question posed basically involves a vehicle traveling at C and then emitting light. I am in search of the most accurate formula for calculating the shifts in wave length. I had a quick chat with an unknown physics professor who passed the dry erase board I was using. He had enough time to tell me, I think, that Relativistic Doppler Shift Formula is not the most accurate for this, but not much else. Though with the R.D.S.F I think I can still "legally" get the answer of 1.0. This would be a one hundred percent increase in wavelength which, to me, makes sense. Though I have muddied my own waters and catch myself mixing in things dealing with absorption lines. haha :) any help would be much appreciated and thanks for the post!