See this article:
http://cusbc.soc.srcf.net/shooting-tips
Down under "sighting" it shows a typical sight picture. I personally prefer a larger black circle with just a very thin ring of white visible around it, but that's personal preference
So I had a few minutes just at dusk/dark to try it, I was surprised at how well it worked as far as seeing the target in the gloom. Bigger targets are easier, definitely. By the time I finished it was more moonlight than anything, but I could still see the front ring and target fairly well.



















































