Last night, I managed to take my first successful picture of a nebula--the Orion Nebula (see picture below). I'm incredibly ecstatic, as before I had been limited to taking images of the moon.
I used a 25 mm eyepiece with my AWB 130 Newtonian telescope (650mm focal length and a 130mm aperture). I mounted my Samsung Galaxy S10 to my telescope and took pictures using pro mode. Unfortunately, I only discovered the picture above in my gallery after I had wrapped up with my stargazing; I can't remember whether I took the picture with my phone's basic camera app or one of the two photography apps I downloaded off of Google Play last night in order to photograph the Orion Nebula.
I fiddled with the various settings on my camera app and the two other apps, DeepSkyCamera and ProCam X, for some time before I (unbeknownst to myself) miraculously took the image posted above. I had no knowledge whatsoever how any of the settings (ISO, shutter speed, white balance, AF) would change the picture, so it is indeed a miracle that I even managed to get the shape, much less the hues of the nebula.
Today, after reading various articles, I now understand what most of these settings mean. ISO makes images brighter but at the expense of more noise. The articles I read usually suggested 800 or 1600 for astrophotography. Generally, articles suggesting higher ISO settings assumed that I would be stacking my images, which I'm not sure I can do. In regards to aperture, Lower f-stop numbers allow for a larger aperture, which means that more light enters the aperture and I can use a lower ISO to reduce noise. White balance changes the tone of the image.
I also read about the shutter speed and the 500 rule--shutter speed=500/(Crop Factor)(Focal Length)--but I'm not sure if the Focal Length is just the eyepiece's focal length or the camera's and the eyepiece's focal length combined. If the latter is the case, would I have to find my Galaxy S10's focal length? Would the 500 rule apply?
What ISO setting, shutter speed, and focus setting would you recommend?