You could have the IR-blocking filter in the camera replaced by a clear filter or a filter with a cutoff at 800 nanometer, and the sprites will then show up much better. You now used very high ISO and still don't see the weak parts of sprites. With an IR-converted camera you could get similar results at ISO 3200 with more details in faint parts and less noise.
But the camera must then be able to use a custom white balance (also green-magenta, or white screen calibration) and use it in video mode.
Hi Oscar,
Thank you for suggestion. But it is too new to modify . I would enjoy true color for the time being. May be many people want to know it also.
Low-cost monochrome ultra-hi-sensitivity HD cameras (like watec in SD) may be expected most now.