A sphere flies past you at and you photograph it side-on. Length contraction flattens it along its direction of motion by a factor of . Does the photograph show a flattened ellipsoid?
Solution
No — the outline in the photograph is still a perfect circle.
A photograph does not record where the parts of the sphere are at one instant; it records photons arriving at one instant, which left different parts of the sphere at different times. The light from the trailing edge left earlier, when the sphere was further back, and this light-travel delay exactly compensates the Lorentz contraction of the outline. What survives is an apparent rotation of the surface pattern — the Terrell–Penrose effect: a fast sphere looks like a sphere turned, never a sphere squashed.
The trap is conflating two operations. Measuring length means locating both endpoints simultaneously in your frame — that gives the -contraction. Seeing folds light-travel time into the picture, and aberration happens to map circles to circles. Contraction is real; it is just not what a camera measures.
Deeper in the notebook: 07. Relativistic Doppler Effect, Aberration, and Beaming · 01. Minkowski Spacetime and the Lorentz Group