An officer MUST review the pictures and sign that they beleive the charge is correct and that they believe the camera system was in proper working order, so this officer MUST come to trial to testify to this information. They may not have any notes regarding the event, but they still must sign the ticket and that means they need to appear in court if you ask for a trial.
You should read the regulation on red light cameras:
https://www.ontario.ca/laws/regulation/990277
Consider is that Section 4 (1) of the regulation, it says the officer needs to serve you (by mail is fine) within 23 days of the offence. According to the ticket, what is the deemed service date? On the surface this deemed service date may seem okay, however I would cross-exam the officer on this point. Did the officer put the notice in an enevelope himself, put a stamp on it himself, and then place it in a Canada Post mailing box himself? If he simply signed it but then left it for somebody else to mail, then how does he know what day is was mailed? The section says that you may be served when the officer "sending the offence notice by regular prepaid mail or courier". I would argue that unless the officer put the letter in the mail box himself (or took it to the post office himself) how can he know for sure that it was "mailed" on a specific day for sure? It is certainly possible that the person who mails them out had it sitting around on their desk for a few days before they got to the post office.
Also consider cross-examining the officer on the what it says at the bottom of the ticket in the PLEASE NOTE section. "The Provincial Offences Officer has certified that the red light camera system used in the detection of this offence ... was in proper working order ... traffic signals were in proper working order". So this would bring up questions like "Officer did you go out and test this system? How did you test? When did you test? How do you know it can accurately measure speed of moving vehicle? How do you know traffic lights were working properly that day? Did you observe them?"
If the officer does not provide any notes for disclosure, then how can they testify that they know it was in proper working order?
If you call around to various paralegals, you will eventually find one that would be willing to take it. Can they win? Maybe, maybe not. I would suggest you ask for trial and ask for disclosure (officers notes) and see what you get. If you get nothing with regards to "proper working order" of the system, then you have a good chance to beat it. But again, you need to find a paralegal that is good at cross-examination or do it yourself. Alternatively, ask for the trial and then show up and talk to prosecutor about reduced fine.