When I set up my P900 for time lapse star trails it shows the ISO as 100 in the bottom left of the monitor screen and no matter what I have tried, I cannot change the ISO to say, 1600 or 3200 for a shoot. I have changed the ISO setting to 3200 in M P A S mode but when I go to time lapse star trails the ISO still shows as 100. Is there a way to change the ISO setting? Thanks for any help.
From Nikon P900 field test imaging-resource.com:
High ISO Performance
[...] The camera's ISO sensitivity setting affects the camera's maximum exposure times. Only at ISO 100 can the camera shoot at its maximum shutter speed of 15”. At ISO 200, the maximum shutter speed is 8”. At ISO 400, the maximum shutter speed is 4”. At ISO 800, it's 2”. At ISO 1600, it's 1”. At ISO 3200 and 6400, it's ½”. Even in full manual mode, these limits remain. Unfortunately, this means that the P900 cannot be used for any night landscape work that doesn't feature a lot of artificial light.
It sounds like whatever you did after setting ISO 3200 in Star Trails mode set the shutter bulb to 8–15 seconds, which caused the camera to limit ISO to 100.