Every photos I have seen of drones taking images at high altitudes, had a kind of curvature at the edges of the photograph. I mean, I know the earth is round. But it is also huge, and IMO, you shouldn't be able to detect the curvature at some 10's of meters of height. But then what makes the effect so pronounced that makes the image highly curved at the edges?
Drone do not curve images. Camera lenses do. You can mount different types of cameras or lenses on a drone but many models now have their own built-in camera which usually incorporates a small fisheye lens. This allows them to have a huge field of view and so they do not need to fly very high to see an entire scene.
Well, now you just need to google drone telephoto images.
Itai pointed you. If you mount a wide angle (or a super wide angle lens) you have that field of view.
The technical problems for cheaper drones or general public ones, to achive tighter shoots are 3.
1) If you do not have a wide angle lens, you need to be more specific where are you poinging at. It is not a panoramic image anymore.
So you need a little more expensive system witn a wifi viewer, so you know where to point at.
2) If you need a tighter frame, the drone need to be more robust to provide you enough stability and not having a shaky footage.
3) A bigger zoom means a bigger lens, and heavier. So, again you need a bigger drone.
And a non technical one.
4) The general idea of an aereal view is to have a "big picture". That is why you use a "wide lens". If you want more detail you normally use a higher resolution and after zoom at a detail.
That is why theese images or footage are more specific like surveillance. But, you can photograph whatever you need if your camera/drone combination allow it!
Do a Google image search for "fisheye lens horizon", and you'll see lots of curved horizons. In fact, some of them curve in the opposite way, implying that the Earth is a curved sphere, and we're on the inside!
Of course, what's happening is that many wide angle lenses distort straight lines into curves when the lines don't go through the center of the field of view. Generally the curve will be concave towards the center of the field of view, so when you point your fisheye lens below the horizon (as in most drone photography) the ends of the horizon are bent down. But, if you point your lens above the horizon, the effect will be reversed and the ends of the horizon line will be bent up.
A lot of the "Whoa! You can see the curve of the earth!" images shot by LEO astronauts are (mostly) caused by this fisheye effect.