I thought this was interesting – I was sifting through a sequence of photos taken, all much the same, and then suddenly they went darker. The difference? The light one on the left was taken immediately before midnight, and the one on the right immediately after. They are both 75 second exposures. The significance of midnight? St. Albans District Council have recently started turning off 80% of street lighting at midnight. What a difference! I assume some London councils are doing a similar thing, since I was shooting to the south at the time. The bottom exposure is after image processing to remove the light pollution. The subject is the M5 globular star cluster in the constellation of Serpens.
