Does the MagBeam really produce more light out of my flash?
Yes and no. Light naturally wants to travel in all directions in a spherical pattern, from it’s origination point. Speedlite flashes use Fresnel lenses to help focus and collimate (collimate is a fancy word to “point light into a column”) the light to increase the effective output of your flash. Fresnel lenses focus light into a particular direction to make it seem like your flash is brighter than it actually is.
The MagBeam Tele Lens does the same thing that your speedlite fresnel lens does, but it has been designed to be a lot more “powerful”. In other words, it takes the already focused light from your speedlite, and focuses it even more!
While the MagBeam isn’t increasing the total light being created by your flash, it is focusing and directing more light from your flash than you’re probably used to. The MagBeam effectively gives you more light from your flash because the light is being focused—and that means faster recycle times, potential longer battery life, and increased control over your light!