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Combining Long Exposures

Quick Photography Tip

I was at my in laws for the weekend a few days ago and for some reason I couldn’t sleep so I took my camera and my tripod outside to shoot some long exposures. This is something that I rarely do and I always tell myself to try it more often because it’s so different. My friends know me for shooting a thousand pictures a day non stop (I’m terrible in vacation…). I guess that the digital age sometimes makes us forget what photography really is: taking our time to set up the shot. Long exposures requires that.

I was trying to photograph the house, but I couldn’t get it right. Since there was a light attached to the it, the contrast between the grass and the house was way too high. It was either the house surrounded by pitch black darkness or the house overexposed. It didn’t look like a long exposure at all. To achieve the picture and the style that I had in mind, I took two different long exposures and combined them together in Photoshop. Here’s how I did it:

Shooting the 2 exposures

Setup your camera on a tripod and frame your shot. Choose your exposure according to what matters in your frame. Here’s what I did in my case :

Exposure #1 : The house
4 sec at f/13

This is the best exposure I could get for the house. As you can see the grass is quite dark and I need one more exposure for my composite. Some parts of the house are a bit blown out, but I’ll fix it Photoshop later.

Exposure #2 : The grass
10 sec at f/13

Now I have much more details in the grass and the tree on the left. I wanted something that still looked real, so I kept some part of the image dark by exposing my picture for an additional 6 seconds. This exposure gives me nice highlights on the grass and that’s exactly what I was aiming for.

Compositing the exposures in Photoshop

Easy stuff. Fire up Photoshop and open both exposures in the same document. Put the overexposed picture on top and add a layer mask. With a very soft brush, mask out the blown out parts of the image. It’s useful to lower the opacity of your brush to keep a natural feeling. Depending on your image, something between 15% and 50% should be good… But it’s not rocket science, so play around with the softness and the opacity until you get a nice result.

Here’s what my mask looks like :

I’ve solo’ed the layer so that you can see the checkerboard, but you will of course need turn on the layer underneath when you mask out your picture in order to see the actual blending of the two exposures. Here’s a GIF to show you the before and after of the composite :

Retouching

Now, retouching is definitely a subject for another day, but that’s roughly how I graded this picture:

  • Sharpening the image with the Smart Sharpen
  • Cropping and reframing the picutre
  • Recovering details from the blown out highlights
  • Adding a soft vignette
  • Cranking up the midtones and the highlights of the grass
  • Lowering even more the exposure of the house
  • Removing some red and yellow to get a cooler bluish look using color curves
  • Adding a blue layer at 20% using the soft light blending mode and masking it
  • Removing a notch of overall saturation

Here’s a GIF showing the first exposure + the composite + the grading :

Final result :

…and another picture from the same night using the same technique :

Camera specs:
Canon Rebel T1i
Sigma 10-20mm f/4-5.6

That’s it for now, cheers!

Charles-Etienne Pascal is a freelance digital colorist working in Montreal, Canada. His line of work mainly consist of advertising, but he also very much enjoys grading music videos, short films and documentaries. Chuck likes photography, motorcycles, travelling, bouldering, guitar and of course color grading.

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