Mr. Hornsby is correct. And most people don't challenge tickets in court, because the maximum fine that can be set by the judge if you lose is much higher than the automatic fine imposed.
However, if you are determined to fight the ticket, there are technical defenses. If the officer calculated your speed by pacing you, there is one set of regulations that apply. If the officer used radar or laser, there are another set of regulations, including a requirement that the initial speed determination must be made by other means, and the radar used only to confirm.
In short, it will cost you attorney's fees in excess of the fine and could possibly result in a higher penalty, but it can be done.
BTW, if you decide to stand up to the officer, Mr. Hornsby would be an excellent choice as your lawyer.
Please remember that Q & A forums such as this one are intended to provide general information, not specific legal advice upon which you should rely in making decisions about your case. Before making any such decisions regarding your case, please consult a lawyer .
This is the bane of the criminal justice system: The "he's lying" (or as I prefer, "he's mistaken") defense. While it may be true its almost never provable, and that's what court is all about... proof.
In Florida you have 3 choices when it comes to speeding tickets. 1) Pay it (which will result in points on your license and an entry which will remain as a conviction on your driver history); 2) Fight it (which will require at least 1 court appearance and will result in a best case scenario of a dismissal, a worst case scenario of an adjudication - points - a fine and court costs, or anything that the Judge wishes to sentence you in between those extremes); or 3) (If you have not done so within 12 months and not elected to do so more than 5 times in your life then you can) Elect driving school (which will result in no points and a minimal fine).
Its a sad reality but its also true that, on their own (or "pro se"), very few folks beat speeding tickets. The best shot that anyone has at doing so will involve hiring a lawyer (ticket specialists are generally quite good at this and know precisely how to attack the credentials, credibility and reliability of both the machinery and the operator), and, given the tone of your question, that is precisely what I would recommend that you do.
Best of luck!