Well, come on, who of you that have tried this got it right first time?

500 - and there nearly wasn't ever going to be a 501th. Triggered the camera on a cable release then headed off to do the light trails - without the torch on so as to not create too much light pollution - and promptly fell down a hole. Fortunately it was only 3 feet deep, not 300 feet, otherwise this really WOULD have been a long exposure and some lucky tourist would have found an unattended Nikon in a remote field in Cornwall.