Unless the focal length of the G7 lens is three times greater than the G2 lens, it won't be 3X less divergence. I think I know why you are asking this, I can't yet find the specified focal length of the G7 lens, not even on Sanwu's web site.
What amount of divergence is acceptable to you? Which diode? If you want low divergence, putting a BE in front of either of those lenses will reduce the divergence further, but a longer FL lens always wins in the divergence contest and from what I gather the G2 has the shortest FL of those two. Best of both worlds of those lenses is a G7 with a 3X BE, or higher amount of expansion. If you are considering the Sanwu "3 X" beam expander, it's reported to really be 3.3 X. Also, the new DTR G8 might have a longer FL than the G7, but there is a limit to how long the FL can be inside the small threaded mounts we use, if too long, the beam will get cut off or truncated inside the small barrel on the way out.
From what members are saying, the G8 appears to be the most favored lens for our pointers right now:
DTR has a new lens in the line up, it's the G8, a long FL single lens broadband 400nm - 700nm The spot/bar size at 15 feet is comparable to the 3 element and the power test is with a nice strong NDB7875 running at 2.4a DTR G2 = 3139 DTR G3 = 2610 DTR G8 = 2921 3 element = 2475...
laserpointerforums.com
DTR's Laser Shop Laser Related Parts Emporium. Diodes Laser Drivers Collimating Lenses 12mm, 20mm, 25mm and 35mm Copper Laser Diode Modules Diodes 450nm 7W NUBM44-V2(NUBM44-81/NUBM47-A1) 520nm 1W NDG7475 488nm 55mW GH04850B2G Lenses DTR-3E-R DTR-2E-G DTR-3E-B DTR-G-2 DTR-G-3 DTR-G-8...
sites.google.com
Edit: Did you see this thread?
https://laserpointerforums.com/threads/sanwu-g2-vs-g7.97280
