Probably yes. The more light the better really. The hole in the foil is so small that you're only getting a few percent of the light transmission that you would normally see, if it was a camera it would be something like f128. Even though the paper is white and the dot black, under these conditions you may find that through the scope the paper appears very dark grey and there's insufficient tonal difference to spot the slightly darker dot as you swing over it. The dot will be blurred and the 40 mag means that even really small movements are huge through the scope. I find it easier to use a cleaning felt to make the hole so I can do it indoors on a bench rather than in the woods and clip the paper to a cardboard box with something in it to catch the felt. Felts are unstable in flight but even if you have a flip fitted there should be no more than a couple of inches between the crown and paper so any error will be almost zero. It can take a while to locate the dot though, it may help if you make a 1 or 2 cm dia solid red circle with a 4 or 5 mm black centre to help find it. If you see red you know you're close and will be able to work out which way to move the scope to centre it on the dot.
ISP Airstream MK III No 15 which is a bit poorly at the moment and having a rest
AA Pro Sport + Ginb FT8 stock + Bushnell 4200 6-24x
EV2 MK1 + Leupold Comp 40x
Weihrauch HW100 KT laminate
SBFTC Competition Secretary
Last edited by Monty; 21st July 2015 at 08:14 AM.