SUNSCREEN in UV

Another test that you could have done would have been to spread sunscreen onto some UV transparent sheet(not sure exactly what would be best) and then seen how much UV got transmitted through each sample, essentially how much UV your skin would receive.

What wavelengths of UV was the camera sensitive to? Just like visible light isn't one colour, UV is a spectrum, so even though SPF 50 and SPF 100 look similar at one wavelength, they may have different overall UV "colours" Just like an apple and an orange look the same in blue light.