An apochromatic lens is one which reduces spherical and chromatic aberrations. (The first part is where stuff looks a weird shape in the photo despite being fine in reality and the other bit is that weird purple haze you sometimes see round the edges of photographic subjects.)

 

I’ve used my own apochromatic lens to photograph a grapefruit. See, no aberrations!

Yes, I am married to a photographer and yes, the poor chap has been interrogated mercilessly for details whenever photographers appear in stories, such as my romance novel, Leave Nothing But Footprints.  Thanks for asking.