Thank you to everyone in my earlier thread who helped me to find the right collimation tool for my 500/114 (f/4.39) Newtonian.
To summarize the feedback I got, I decided not to get a laser collimator, and to get a combination collimation eyepiece instead, with a length shorter than the focal ratio in inches. I got the Astromania 2.8-inch combination collimation eyepiece, and it looks like it works perfectly in the f/4.39 Newtonian. However, I am still not sure how to interpret what I am seeing in the collimation eyepiece. I attempted to take an afocal photograph though, so please give me any feedback you might have on whether the telescope needs collimation or not. If I need to take a different photo, let me know. Photo attached.