Technique for Multiple exposures:
This isn't that different to normal HDR really, you just have to be careful with really high contrast scenes as you can end up with a selection of shots that all have burned out areas.
It's worth taking more shots than you'd usually take in the daytime too – around 5 shots each two stops apart is a good place to start.
Multiple exposures in the evening - See how multiple exposures can improve your evening shots.
- Tripod – you don't want the camera to move in between exposures
- Torch – it can get very dark once the sun sets
Don't wait until the light's gone completely to set your gear up either as taking your first exposure just after the sun has gone when there's still a spot of colour in the sky will give you a pleasing night sky for your twinkling city lights to sit against. Try taking a shot that's slightly underexposed too as when it comes to blending the images together you may find the slightly darker sky gives the impression that the final image was taken later at night.
Once you're happy with your shots of the sky you can get your flask of tea out and wait for all the colour to slip out of the sky before you take your next exposures or take advantage of the rapidly darkening sky, shooting as the light fades and the lights switch on, giving your image foreground interest without a big black sky overpowering the shot. Make sure you don't move your camera while you're sat in the cold as even the smallest of knocks can mean the lights in the scene don't line up with the buildings and lamp posts they're meant to be shining from.
Watch your white balance as street lights are very orange so try shooting in tungsten.
For excellent light trails, use a longer shutter speed and wait until the cars are moving before you take the shot - if they're stationary on one shot, but not the rest, your HDR may have a "ghost" car on the shot.