Greymouth photographer Stewart Nimmo said he knew Mr Duncraft well and suspected that his view through the camera may have given him a perception that the train was further up the track.
"It's really hard to know what happened, but sometimes things do look further away than they actually are,'' Mr Nimmo said.
Mr Duncraft may also have been confused by the double set of tracks at Kokiri, and may have been expecting the train to be on the other line when it came around the bend.
The 200 passengers on the train were unaware of the drama unfolding in front of them but the crew, powerless to stop, could only watch in horror. They have since been offered counselling.
Steam train Ka942 was making a nostalgic return trip from Christchurch to Greymouth, and the accident was witnessed by a number of others also taking pictures as the train passed close to the Arnold Valley Road.
Mainland Steam Heritage Trust operations manager Michael Tollich said Mr Duncraft had trespassed on railway property by crossing the first set of railway lines to get in position for his photo.
Mr Tollich said he sympathised with the family, but the accident was a timely reminder of the inherent danger of trespassing on railway lines.
"Tracks are for trains not people.''
Mr Duncraft was flown to Grey Base Hospital by the NZCC Rescue Helicopter, which was summonsed to the scene along with other rescue services. Their efforts and investigation of the accident delayed the train for two hours.
A train engineer with no connection to the accident said it was tragic but preventable.
"I'm surprised that it has not happened before. We have guys with cameras jumping out in front of us all the time, it's crazy, they don't seem to realise that we can't stop these things (trains) on a dime. I have had too many close shaves to count.''