The Fuji S5600 sensitivity to IR does not appear to be very good at all. The image below was taken with maximum extra exposure compensation dialled in:
The JPEG straight from the camera, exposure 1/4second at f3.2.
After the use of Levels.
In fact the issue with the 5600 seems to be both the sensitivity of its expsoure meter to IR and the sensitivity of its imaging sensor. The exposure meter is more sensitive to IR than the imaging sensor.
This image, from the red channel only, was shot at 3 seconds and f5.6, a lot more exposure than the camera’s meter would have given.
Nice images are quite possible with the 5600, but I would advise shooting in manual mode. Noise is nicely minimal when shooting at the minimum ISO setting.
At 100% and unadjusted, you can see both the quite low noise and the low level of exposure in all except the red channel.
Blue with levels