When I fly I am very careful to match the sunglasses to the light. I use a pair of ski glasses on very bright days. Why - You need sunglasses that protect you from 99 percent to 100 percent of both UVA and UVB light. [This includes those labeled as "UV 400," which blocks all light rays with wavelengths up to 400 nanometers. (This covers all of UVA and UVB rays.)]

If the light is flat - poor definition of colours - often found on days with total cloudcover I use a pair of "axis blockers" see www.axisoptical.co.uk they make the model stand out and increase the cloud definition.

I do not like polaroids.