Editing steps
1 Load up your layers
First, go into Adobe Bridge and select all of the images in your light painting series. Next, head to Tools > Photoshop > Load files into Photoshop Layers to bring all of your various light painting exposures into one single Photoshop document in the layers stack.
2 Align the images
In the Layers panel (Window > Layers) click the top layer, then hold down the Shift key and click on the layer at the bottom of the layers stack. Now go to Edit > Auto Align Layers. Leave the Projection set to Auto and then hit OK to make sure all of your layers are perfectly aligned.