Say 50mW of blu can light a match where the focused point is 1mm2 = 50mW/mm2
An unfocused spot is about 10mm2 = 500mw/10mm2 = 50mW/mm2
Of course these numbers are hypothetical, and presume that match-lighting is a function of power density on the head only, wavelength and absorption are the same, and the beam is equally still for each burn.
Ian its questions like this that got you banned numerous times. People are going to great expense to do proper tests for the benefit of us all. The whole forum is concerned with power settings, longevity, beam characteristics, ect. At $200+ a pop, the last thing people are concerned with is if it can light a freaking match. You are insulting peoples intelligence and hard work. On top of it all the question is in the wrong area. Use your freaking brain, learn from your mistakes, and wake up or your a$$ is going to get bounced out of here again.
As you have likely read, the 8x BLU is a BURNER. Most of us here have risen above parlor tricks of POP and LIGHT. That is child's play anymore with the new LD's and optics.
Focusing any laser for a match light at distance requires a stable mounting for the laser and careful focus adjustment just like any laser. Hey guy -- give your 8x a try at say 40 feet and tell us about it.
I hate to admit, I've popped a balloon at 35 feet with one of my BLU's. Don't tell anyone
The OP said nothing about distance. He (or she) asked if an 8x can light a match focused at infinity. I set my 8x on the table and the "dot" focused over 40 feet away. I then placed a wood red-tipped match 6 inches in front of the 8x and it instantly burst into flames. No focus was needed AT ALL.