What the camera sees is quite different from what the eye sees. What had looked like a big well defined circle by eye, turned out to be almost square with a circular hotspot. I added some diffusion in front of the flash head and some more behind the grid and was able to get a more even coverage but it cut a fair amount of light.
The other thing I realised was that the grid I had been comparing it to in part one, was quite a long one, but the 24cm grid is only one inch deep, consequently the light was able to spread more, so the comparison wan't entirely fair. I compared it instead, with a short grid made out of drinking straws.
The drinking straw grid produced a larger brighter circle which was very clearly circular, unlike the 24cm gridspot which was distinctly square. Why were the shapes so different? I think it is because the square section of the coroplast allowed the light to escape at a wider angle on the diagonals, but on the straw grid the angle is the same in every direction. I think it would be an interesting experiment to try different shaped grids to see what sort of pool of light they produce.
So far it wasn't looking very promising, the size, shape and power of the light wasn't very good. But did it do what it was designed to do? Did it soften the light?
So grudgingly, I have to conclude that the humble straw grid outperforms the gridspot in pretty much all areas. Its a great deal more convenient to take with you too. But I did learn a few things from this experiment.
1. The light source has to be a lot bigger to soften the light. 2. The shape of the holes in the grid affects the shape of the spot 3. The small straw snoot rocks