I'm a terrible photographer. When people talk derisively about 'point and click' photos, I wonder 'is there another kind?' But this brackets me with most of the world's population, so my attempts at photographing objects in the sky should be more representative than those of an expert.
I took the photo below yesterday with a Samsung Galaxy phone, a few years old, on standard default settings, whatever they may be. While out walking, I noticed a plane (passenger jet) in the distance, got out my phone, and took a quick snap. This took maybe 5 or 6 seconds: a few seconds to get the phone out, activate it (it was already switched on, which may not always be the case), and select the 'camera' option, then another few seconds to take the photo. I didn't take much care with this, and couldn't even be sure if the plane was in shot, as the sun was shining on the display screen and I could hardly see anything. (This can be a problem even when the sun is not on the screen, as ordinary daylight is much brighter than the image.) Here it is:
So what do we see? First, I note that despite my photographic incompetence, it is quite a clear image, not badly out-of-focus at any distance. Second, the plane
is in shot, but you are unlikely to see it without blowing up the image, and knowing where to look. In fact, it is just above the right side of the white van, and roughly level with the top of the lamp post to the right. If you
do blow up the image, at a high magnitude it is easily recognisable as an air liner, but then we all know what they look like! For comparison, note the dark detached object, somewhat larger than the plane, above the white van and just below a small white cloud. I didn't notice this when I took the photo, and most likely it is just a leaf which happened to fall from the tree at that moment. It is similar in size and colour to other leaves on the tree. But without that visual context, it would be difficult to identify. Indeed, it has some resemblance to a bird in flight, if the right extremity of the object is its head and beak, the left extremity is its tail, and the downward projection is the downstroke of a flapping wing. I can't be sure that it isn't (say) a pigeon or a green parakeet, both of which are common in the area.
Though the plane is difficult to see in the photo, I could see it quite clearly with the naked eye (with glasses). Here I note that a photo, viewed from a normal distance, is usually compressed into a smaller field of view than the original scene viewed with the naked eye. A moderately magnified photo is actually 'truer' to the naked eye view than an unmagnified one. A linear magnification of about 80% gets quite close to what I recall seeing. A higher magnification (say, 200%) reveals details, like a car number plate in the distance, which I don't think I could see with the naked eye. This confirms that a fairly basic phone camera actually records more detail than the eye can see.
As to the distance of the plane, I estimate it at a few miles. I used the 'fingernail' test. The nail of one's little finger, at arms' length, spans about half a degree. In this case the plane spanned a bit less than half the fingernail, so it spanned about a quarter of a degree. At a distance of a mile, 1 degree subtends about 100 feet, so a plane more than 100 feet long subtending only a quarter of a degree would need to be at least 4 miles away.
