I have some very old binoculars that I…guess have a 4x zoom level, I took a picture of an object with a phone and then the same thing through the binoculars (the object as seen through the bino’s), then in photoshop I resized the original small object and upscaled it to fit the zoomed in one and due to pixelation from the phone’s camera I couldn’t tell entirely, but it’s around 400-500% the size of the original object, so the zoom on the binoculars is 4x or 5x.
A few days ago I had the Airbus A-380 fly above my city (on cruising altitude, 35-ish thousand feet) and I managed to catch it with the binoculars, I could kiiinda see the general shape of the plane, but it was still not enough, despite the A-380 being the largest plane I could hope for. There’s an extremely cheap monocular that is 10x25 or a slightly more expensive binocular that is 10x50, it’s not much, but would either of them be enough for plane spotting?
Another thing I could do is save up some money and get a 20x50 one, a 30x50 or even a 50x50 one, I suppose that at least one of these should be enough, if not even an overkill. There are even 75 or 100x level zoom ones, but they are way out of my budget at the moment and I don’t have a justification for spending that much other than the planes.