A little on optics light gathering ability whether scopes, bino's , spotting scopes it doesn't matter the same principle for all 3 . Tube diameter has no bearing on light gathering ability. Exit pupil = objective lens dia divided by power gives you exit pupil diameter. Example 50mm objective lens dia ( the front lens) divided by 10x power = 5 mm exit pupil, that same 50mm objective lens diameter with a scope set on 3x power = 16.6 exit pupil. Here's where the exit pupil is important in general I'm sure there are a few people out there that are the exceptions, young people can dilate their eyes to around 7mm (exit pupil), middle aged persons can dilate their eyes to around 6mm, old folks can dilate their eyes to around 5mm. What this means your eyes normal dilated can only bring in 7mm, 6mm, or 5mm worth of usable light depending upon your age. Now if you have a high powered scope say 50 mm set @ 24 x power the scopes exit pupil will be 50 divided by 24 = 2.08 mm exit pupil so what this says even an older persons eyes can dilate to 5mm exit pupil and the scope is only allowing in 2.08 mm worth of light making the older persons eyes dilation more than the scope can give them, now if you cranked the same scope power down to 10x power you would have the scopes exit pupil increase to 5mm which would be the maximum eye dilation for an older person. Something to try take the rifle outside and look at a hill side , tree, rocks, something with defination right at dusk with your scope crank the scope up to say 9 or 10 x and then imediately crank it down to 3 or 4 x and see the difference in light gathering ability. if it's already light or dark out it really doesn't matter you either see on all power settings or totally dark you don't see anything. This works on any type of variable power optic, if your optic is fixed power then you are stuck on whatever the exit pupil of the optic making it a little harder to see very early in the morning or just at dusk the variable powers give you a few extra minutes each day depending upon just how powerful your optic is. Here's something to keep in mind we are NOT talking optics quality and lens coatings these are different subjects that can enhance your ability to see things clearly so not to be confused with your ability to see things clearly early morning or dusk we all know good optics build & lens quality is very important on how we see. Years ago I had to test this for myself sitting on a hill side right at dusk with a pair of 10x Zeiss bino's and my rifles scope was a Leupold 2.5 x 8 x Vari x III , I couldn't see squat on the hillside with the 10x binos, or rifle scope on 8x, until I cranked the rifle's Leupold down to 2.5 x then I could see all sorts of things until it got too dark to see anything and had to hike back with a flashlight.
Fire dots and lighted reticles can be very useful so long as you are absolutely sure of your target and beyond. Reticle choice to me is very important. I inherited my folks Lee floating dots and ultra fine cross hair scopes , couldn't see either reticle in the brush so I changed all the scopes out to other reticle types. Back then we normally used iron sights anyway so going to a better scopes was like this is way better for distance.