Photographing fire - white balance

Tasmaster · Sep 30, 2010

Two photos, same fire:

The first photo looks spot on to me. The magenta stuff in the second are actually glowing orange embers. AWB picked 4150 for the first one and 3100 for the second.

These are from RAW, and I can correct the second photo by taking the WB slider into nuclear territory, but it is a finicky job, and I have to rely solely on judgement. It takes some more fine-tuning to bring it to proper color.

Any advice on setting white balance to get the best result in-camera for this kind of lighting? Why does getting the embers in the shot throw off the WB that much? Is it because there is mixed yellow (flames) and red/orange (embers) lighting? Could it be infrared radiation? 2nd photo was at f/1.8, 1/8 and ISO 800, more than enough to completely overexpose through an R72 on a sunny day.

Village Idiot · Sep 30, 2010

I manually set my WB and keep it to about 5600K to get an acurate representation of the flames. AWB sucks.

Tasmaster · Sep 30, 2010

Well in your photos there is artificial light as well. Another thing is that when setting WB in Lightroom, the same value results in very different colors. If i copy the first photo's value (4150), the yellowish parts of the photo are ok, but the embers remain magenta. To fix these through WB i need to set it in the range of 15000, which doesn't seem normal to me.

PS: as i am typing this, a google search for "photographing embers" (without the quotes) returns this thread as first result, how is that for SEO :lol:

Village Idiot · Sep 30, 2010

Tasmaster said:
Well in your photos there is artificial light as well. Another thing is that when setting WB in Lightroom, the same value results in very different colors. If i copy the first photo's value (4150), the yellowish parts of the photo are ok, but the embers remain magenta. To fix these through WB i need to set it in the range of 15000, which doesn't seem normal to me.

PS: as i am typing this, a google search for "photographing embers" (without the quotes) returns this thread as first result, how is that for SEO

Just the second one and that doesn't matter. They were both set to 5600K.

filmshooter · Sep 30, 2010

Could you use a feathered, freehand selection tool to select the embers in LR and adjust the WB to get the color you want? I don't have LR, I use GIMP so I don't know. If you can't get everything to look natural with the WB slider on the entire photo, maybe try that?

Flash Harry · Oct 2, 2010

Try googling color temperature, hopefully it'll explain something about the numerical values, their uses etc, or you could buy a photography book, Micheal Langdon, Advanced Photography, to enlighten yourself. H

Tasmaster · Oct 2, 2010

I know what color temperature is, thank you

. The problem here is the light source. The light coming from the flames and the embers obviously looks very very different to the camera sensor - if not to the eye. Now, i don't have access to a bonfire in my appartment for further testing, but i do have several remote control devices and that magenta color is what infrared light looks like with a warm WB setting.

In that case the issue is that the camera is too sensitive to IR (which it is, it's a D40) and there is a strong IR source in the shot, as well as a long exposure time. The first shot is taken at 1/2000 (ie there is a lot more visible light than IR).

Funny thing i am invited to a BBQ tonight, so i might be able to confirm that - and look really weird to the other guests in the process!

epatsellis · Oct 3, 2010

One thing comes to mind, when I have a tricky white balance situation, I will usually shoot raw+jpg, with the jpg used for comping purposes (or FPO). Kodak's Photodesk sofware makes raw file processing to obtain an aesthetically pleasing image trivial.

Tasmaster · Oct 3, 2010

Ok, case solved.

Here is a photo with WB adjusted for the lighting at the BBQ (warm incandescent lights at that spot):

And here is one with a Hoya R72 on:

As expected, the embers emmit strong infrared radiation - and the sensor is only too happy to record it. It is an additional light source in the frame, visible only to the camera, and the effect gets stronger as ambient light gets lower. WB value doesn't really matter, because IR "color" temperature is by definition different to visible light.

With this in mind, picking particular exposure values may help - depending on the scene lighting - but i think the most technically correct way to deal with this would be to expose the photo properly and then isolate the embers and deal with them as needed in pp.