Playing with Smoke

A Ball of Fire
OK enough of the fractals; they still take a long time to generate even with today's PC's. But I'm still in an abstract frame of mind, so I thought I'd have a go at playing with smoke.

Smoke Cocktail
The set up is really quite simple:
  1. A Black background - I used an A2 piece of black mounting board (about £2.00 from your local craft shop),
  2. Incense sticks - I used mellow vanilla incense (about 0.75p from your local 'Hippy' shop), the smell hangs around for ages so make sure it's something you can live with. I don't know of anything else that gives off such a consistent plume of smoke.
  3. A flash gun will help give definition to the smoke. I have to admit I didn't try shooting without flash. I wish I had because getting the right level of flash was tricky - I wanted to bring out the detail in the smoke while leaving the background an intense black. The flash was placed to the side of the incense stick, in front of the camera, and fired remotely by the D80's onboard flash. 
  4. Tripod, and finally
  5. Nikon Infrared Remote Control (ML-L3 RC - about £16.50 from any Nikon supplier).
One that got away - spoilt by light spillage
The most critical aspect of the setup was making sure that light didn't spill onto either the lens or the black board background. Initial efforts had light spillage on the background and no matter what I did in post processing I couldn't eliminate the glare on the card.

I overcame the problem by increasing the distance between the burning incense stick and the background card and then by using another piece of card and tape to fashion a gobo to stop stray light hitting the card.

Focusing and Exposure:  I set the camera to manual focus (it's difficult for any auto focusing system to cope with smoke as there is little contrast between it and the background) but ensured that the lens aperture was set to give a reasonable depth of field. All of the photos were taken at ISO 100, F/8 and 1/125sec (giving a 1 stop underexposure). It wasn't necessary to allow for any flash compensation.

Post Processing: In Nikon Capture NX2 (although if you just want to apply a nice colour gradient to the smoke it might be quicker in Photoshop).

Step1: Brighten the smoke using a combination of Curves, Exposure, and Shadow Protection.

Step2: fine tune the contrast and brightness. The Hue slider selects the targeted colour range to apply contrast to. The colour selected is lightened by the image, while the complementary colour is darkened.
Step3: adjust the saturation and warmth
Step4: (Optional) Invert the colours. This changes the background to white. It also inverts the colour of the smoke - if you don't like the new colour then open the adjustment layers created in steps 2 & 3 to readjust the colour; or adjust Hue and Chroma by switching from Master Lightness (in this adjustment) to Hue and/or Chroma

Step5a: I wanted to apply different colours to different parts of the smoke - starting with the bottom left corner. I first created an oval selection using the Oval Marquee Selection Tool. Then I applied a Circular Gradient to the selection.

Step5b: I then used a (red) colorize adjustment to apply to the selection layer I'd just created. This colours everything in the selection, red - to colorize selectively choose an appropriate blending mode. Here I used the Screen blending mode, but usually I would have used Overlay which would apply the colour to the (darker) smoke leaving the white areas white.

I created several colorize adjustment steps and where necessary used the Minus Selection Brush to remove unwanted areas of colour. Other fine tuning included feathering each selection.

As a final piece of fine tuning I applied Color Booster and Color Balance adjustment steps.

Note: for the "Ball of Fire" image above I rotated the example image and omitted the Colour Inversion Step4.

Man Smoking

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