Digital night photography: Exposure balance

View from the deep end — by Joe Reifer

One of the challenges of digital night photography is achieving a balance between a technically correct exposure and a night-time feel. If you somehow missed the pivotal Luminous Landscape article about exposing to the right on your histograms, it’s a must read. This advice needs to be modified for night photography — pushing the highlights to the right side of the histogram to maximize your total dynamic range is important, but not always the main goal. Rather, digital night photography requires making sure you have enough exposure value to pull details out of the 3/4 tones when necessary, but that your full moon images don’t look like daylight.

If your histograms are clipping in the shadow areas, you probably need a little bit more exposure value. If your histograms are pushed to the right, you may be overexposing. A little bit of clipping on the low end may be fine — you don’t necessarily need to be able to pull detail out of all the shadow areas — sometimes dark areas with no detail can really enhance a night image. The best rule with night photography seems to be expose to the middle.

The image above was exposed for 7 minutes at f/11, ISO 200, with a focal length of 45mm on a full frame dSLR. The exposure time of 7 minutes did not require noise reduction, and is a nice balance between star trail length and shooting productivity. Another option would have been to shoot 7 minutes at f/8, ISO 100, but I wanted to stop down to f/11 to ensure the pool wall and building were both in focus. For more reading on this delicate balancing act, the article Common Obstacles In Night Photography does an excellent job discussing the tradeoffs of exposure time, depth of field, ISO speed, and noise.

You can see from the histogram that under the expose right method this image needs almost another full stop of exposure. The shadows are barely clipping with the exposure set at 0.00 in Adobe Camera RAW, and there is certainly room to bring the exposure value an additional half or 2/3 of a stop without worrying about adding extra noise. But I don’t want any more shadow detail in this image — that would ruin the mystery and feel.

A good strategy for pulling more dynamic range out of this image would be to go ahead and increase the exposure value in the RAW converter by 0.5 to spread the histogram over a wider area. While the image would look too bright in the RAW converter, a Curves adjustment could be used to bring things back to a night vibe.

After some slight tweaks in the RAW converter, this image was brought into Photoshop and further adjusted for contrast and color to create the finished image above. The more intense blue saturation in the sky, and subtle improvements to the foreground tonalities were achieved with a very simple, quick adjustment in Photoshop that will be discussed in part II. Stay tuned.

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