To get a full-size shot of the Earth, we need either a) 28,000 miles (in 1972, Blue Marble 1.0) or b) 1 million miles (in 2015, Blue Marble 2.0). Inexplicably, at 22,000 miles, only a tiny fraction of the Earth is visible requiring multiple splicing to form a composite.
Can you not see that this is problematic?
Let’s review the premise:
A standard 35mm camera has a full-frame size of about 24mm x 36mm. Thus, to take a picture of the ENTIRE earth from space, the diameter of the earth (some 8,000 miles) would have to fit into a 24mm x 24mm circle.
(A "standard" lens on such a camera is somewhere between 35mm and 50mm, depending on who you talk to. We'll take the larger one, since the 50mm lens is a lot easier to produce with very few geometric distortions in it.)
Using a 50mm lens on a 35mm full-frame camera would require the camera to be a distance of 17,000 miles to put a circle of 8,000 miles diameter into a 24mm x 24mm circle on the 24mm x 36mm film size.
So, if you want to get a FULL image of earth using such a system (35mm full-frame camera using 50mm lens), you'll only need to be 17,000 miles away.
Maybe you should be 21,000 miles, though, to get you the 17,000 miles to the closet point and then back to the widest point of the earth (4,000 miles further away . . half the diameter of the earth) to get a good shot.
A geosynchronous orbit is 22,000 miles above the surface of the earth (compared to the 21,000 miles calculated above).
Bottom line: anything in geosynchronous orbit should, in theory, be capable of taking an image of the earth that shows it as a full disc when using a 35mm full-frame camera and 50mm standard lens.
Yet, it isn't, according to NASA.