NavList:

If you are shooting in astronomical twilight I dont think red is critical, there is still ambient light. If you felt the need to do a 1:00a.m. site it would help. I'm 58 now so my vision is not anything what it was and the white LED I'm using in my sextant is an ultrabright. Being able to see the scale especially on the vernier far outwieghs diminished night vision. But the problem with the IIIB is the design of the clear plastic not the light. I work in a lab so I coated much of it with evaporated aluminum in an effort to direct the light better toward the scale, I had to remove much of it becuase where that plastic is intended to direct the light simply does not work. I used a red LED first, ended up switching to white, not so much from lack of intensity, there's just not light well directed to the lower part of the vernier scale so getting minutes is hard down there, the eye is more sensitive to the white. I stiil find it annoynig at the lower paer tof the scale though, tat and where the metal cover allows light to pass to no good use except that it occasioanlly finds a direct path to the eye, then regardless of color you are temporarily blind.