One caveat would be shooting a SFP scope at max power in low light. Gonna be really hard to see much of anything at 15x with a tiny exit pupil in really low light.
exit pupil is the same FFP Or SFP and is a function of the scopes power setting and its objective size. but either way your going to see less scope brightness as the scope goes beyond about a 4:1 ratio. if its a 40mm scope that is going to be 10x+, if its 50mm its going to be 12x+ that is probably why you see a darker image on 15x
My point exactly - if you have SFP scope, you may need to turn it down from max power at last light, making your reticle incorrect and then you'd have to do the math on your subtensions.
. That is a great point I do not generally find myself making those long shots at last light though. It’s all a trade off. I love cussing and discussing optics
I can say after some experience last week with the 3-15 at last light on the range I would not want to be shooting it at an animal at last light at 15x, but I don't have an issue shooting 300-400 at 9x or so in low light. IF I wanted to use the reticle, I'd be up sh*t creek trying to make a split second decision if I had a 3-15 SFP in that situation. Even if I memorized what the reticle subtended at 9x, I'd have to make sure I was EXACTLY on that, and have verified that prior on the range.
