[PlayRaw] Long exposure of waterflow, to process or not to process


(Filip) #1

This is how not to do it story. There are two shots, one is 1/4 and another 2 seconds. Here are exported and resized jpegs:

1/4 no processing

ignore people at top of frame. Rain, cold and they must come and examine water at close distance.

2 seconds processed with dehazing, equalizer and local contrast

the same 2 seconds without processing

My processing effort ruined long exposure and milky water, about 4 stops. Maybe 5 or more stops. 1903 is 100 ISO and 1922 is Lo 1 (50 ISO), both are taken through variable ND filter some mid value, do not remember exactly. Well, 100 ISO requires less time than 50 ISO, so 3 to 4 stops is correct.

Sidecar for processed 2 second shot FED_1922_01.NEF.xmp (2.5 KB)

Released under CC BY-SA 4.0, enjoy

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Without processing you see more of the time-smoothed water. With the processing you’ve gotten more of the underlying rocky structures beneath the water, which to me is more natural looking.

(Filip) #3

Whole long exposure (I see that as goal of this exercise) is lost and it is still not natural, exposure of human eye is 1/100 to 1/200 of second. For example 1/15 will also produce smoothing effect but you can not see that with naked eye.


Well I was speaking more of how natural the stream looks, not comparing with the naked eye. Never heard of 1/100 - 1/200 for eyesight…

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and a dark adapted retina can be as sensitive as a 2s exposure. For motion, the persistence of vision is 1/16…

(senpai) #5

Testing with darktable 2.60

FED_1903.NEF.xmp (5,9 Ko)


Lonely thread here. Here is my take of the two shots. Exact same processing, saved as JPG and then aligned for easier comparison; excuse the black bars.

1. PhotoFlow → HL mode (blend) → CA correction → AMaZE → linear Rec2020 (no clipping) → linear sRGB 32f
2. gmic → filter pixels → my fun “texture” filter → resize (1800) → JPG → move frames to align

Zoom 100%, switch between them and enjoy!


Bonus Animated GIF (GIFs are lower quality than JPGs)