Thanks for that, Bob! That explanation makes the most sense of everything I’ve ever been given, and it also explains why in my early days of shooting a DSLR, when I was advised to have a filter on to protect my lens, I always had green dots, but never had them when there was no filter on. It also explains some of the low-light video I’ve shot.
Here’s a couple examples of the early, filter days…
A BNSF switcher in Hastings, NE, makes a pickup from JM Eagle in town. This was the only time I ever saw anything on this stretch. Also of note, the 3162 is one of only 5 BN(SF) locomotives given an extended, 5-man cab.
A Union Pacific manifest rounds a curve in Hastings, NE, near sunset. Before the line relocation in 1999, the train would’ve taken a left here and gone right through downtown, but now takes this line through the trees, and only across 1 grade crossing.
It didn’t take long to figure out why this was happening, and the filters came off quickly.