#Bookplan2018, Exposure compensation at night shot

Photo Technique: exposure to avoid highlight wash out

When shoot this scene, noticed strong and bright lighting illuminates foreground of the building, it will wash out highlight hopelessly in normal exposure. Compensate exposure for highlight will darken other area too much. Then, bracketing is the only way, right? To balance highlight and dark area & have flexibility of local adjustment with different exposures, I come up with multiple shots as shown in film strip.

In these days, digital Raw file has a lot of information which can be retrieved during post processing (= bigger dynamic range), therefore less concern about under exposure photo compare to film days or earlier days of digital photography. Even so, this kind of extreme lighting induces challenge to determine proper exposure(s). I started from 0, then adjust to -0.5, 1.0, -1.5 stops… and so on. At the end, among 6 bracketed photo, I pick up -2.0 exposure shot and process it as shown in here.

Overall impression is OK as intended to preserve highlight details. But side effect of -2.0 under exposure dominates background. Noise (grain) became severe and harsh. Even with ISO100, noise in the dark area is inevitable if absolute amount of photos is too little.

There are couple of ways to tackle this problem. One way is overlapping normal exposure photo with -2.0 under exposure photo and mix better exposed part of them. This is a basic level of PS if bracketed shots are avaialble. Another method is stacking all available shots into one file to reduce overall noise level, then do post-processing with it. Be noted, this is different from HDR method. In general, HDR  increases noise level during pixel calculations. Here we are talking about ‘stack > mean’ in PS.

‘Stack > mean’ will average out randomly pop out pixels which is noise by its nature, while maintain consistantly appreared pixels as signals. This method reduces noise and add extra tonality to darker area, so end result is less contrasty (in BW) and differently saturate (in Color) compare to original photos. Because of this reason, I can not copy & paste existing presets directly and have to do the work for that specific file. It’s a drawback, but worth to do so to get cleaner fine tonality on the print…



글쓴이 Leo_KHIMME

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