This photograph is RAW and has NOT been edited.
Please take a look at where the focus point is (half way down first carriage.
Focus Point by Colin, on Flickr
Once the train got to where the focus point is I held down the back button focus on my 5D mk3 and pressed the trigger to take the photographs.
Why has the focus point stayed where it is and not followed the front of the train?
Settings:
Back button focus
TV
1/500
F7.1
ISO 1250 (Weather was very dull)
Single-Point AF
A1 Servo
Please take a look at where the focus point is (half way down first carriage.
![](https://farm5.staticflickr.com/4805/31690627437_0567430bae_b.jpg)
Once the train got to where the focus point is I held down the back button focus on my 5D mk3 and pressed the trigger to take the photographs.
Why has the focus point stayed where it is and not followed the front of the train?
Settings:
Back button focus
TV
1/500
F7.1
ISO 1250 (Weather was very dull)
Single-Point AF
A1 Servo