Just got a new dive rite 2" tech SPG to replace my computer/SPG console. I shined my 800 lumen light for about 30 seconds then took it off. After 1 minute its near impossible to read in a pitch black room, after about another minute or two theres no light at all. Also has this weird grainy texture. Compared to my old oceanic SPG this sucks. I took a picture of my old oceanic after two hours in a pitch black room, much brighter. Is this normal for brass SPG's? Thanks