A useful way to compare telephoto focal lengths is to look for side-by-side “field of view” or “focal length comparison” examples. The key idea is that longer focal lengths narrow the angle of view, so your subject appears larger in the frame from the same shooting position.

As a rough guide, 300mm gives about 1.5× more magnification than 200mm, and 500mm gives about 2.5× more than 200mm. Compared with 300mm, 500mm looks about 1.67× tighter. In practice, that means a subject that fills half the frame at 200mm will fill much more of the frame at 300mm and dramatically more at 500mm.

You can also test this yourself: take a photo at 200mm from a fixed position, then crop the image to simulate 300mm and 500mm. Cropping to 300mm means keeping about two-thirds of the image width and height; for 500mm, keep about 40%. This gives a very close preview of framing differences, especially if you won’t be moving the camera.