If I look at an object that is being reflected on a convex spherical mirror it will look smaller than had it been reflected on a flat surface. Does that also mean it will look brighter?

I have two conflicting ideas and can't understand which one's correct.

  1. It must look brighter. While the convex mirror itself doesn't focus light, the mirror together with the lens in my eye focus light. The same amount of light will hit a smaller area on my retina, which means that the object will look smaller but brighter.

  2. It can't look brighter. We could replace the convex spherical mirror with a polyhedron with many faces. If there are many faces the result should roughly be the same as for a spherical mirror. Using a polyhedron all light will hit a flat surface so the object will not look brighter.

Possible objection to 2: all light will hit a flat surface if we replace the sphere with a polyhedron, but the fact that there will be several flat surfaces with different normals means the situation is different from the case with a single flat surface. Somehow this makes a difference.

Counter-objection: each rod/cone in my eye will get light from a single surface, so for them it can't possibly make a difference that there are several surfaces rather than just one.

Counter-counter-objection: some rods/cones will get light from two adjacent surfaces, and those might perhaps get more light (why?), meaning the image will look brighter there.

Any help would be appreciated.


I think that we see objects brighter when the spectrum of light which is reflected by the object changes. For example, fluorescent highlighters are really bright because fluorescent ink actually absorbs UV light and then reflects it in a spectrum which we can see. Also by using a convex spherical mirror, you won't be changing the energy of the source of light. So the spectrum won't change also. My personal answer is no. But I can't say this thought is %100 true. Hope this helps.


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