Archive for January, 2013
Bracketing With Hot Lights And Available Light . . .
Wednesday, January 16th, 2013
In my last post, I discussed bracketing of exposures. Today, let’s talk about bracketing with hot lights. Hot lights are a continuous lighting source and should be regarded as available light, just sometimes very intense, and very bright. A majority of hot lights are of incandescent color temperature, adding a warm or yellow tone to your image. In most modern DSLRs, there is a setting for tungsten or incandescent light which compensates for the warm tint by adding a blue or cyan tint to the image.
Instead of using the incandescent mode in the camera for white balance, I prefer taking one exposure with a gray card in the image and setting the gray reading for all the images I take in that series with my editing software. Outdoors, my cameras are very accurate, so the automatic white balance setting works just fine. Indoors with a mix of lighting, a gray card or an Expodisk is the ticket.
Now, back to bracketing with available light and hot lights. My cameras will do up to nine bracketed shots (different exposures of the same image) automatically. Some cameras only allow three images for auto bracketing. If you desire more exposures for either HDR (High Dynamic Range) images or for layering the images with these cameras, the way to facilitate that is to do it manually. As in my last article, adjust the exposure by putting the camera in aperture-priority mode, setting one aperture and changing the shutter speed to bracket various exposures. My choice is to use 2/3 of a stop difference for each of my brackets. You may like 1/3 stop, 1/2 stop, 1 stop, or ? bracketing stops instead. If doing this manually, try to get one optimum exposure, i.e. the one picked by the camera as the overall best exposure, and make the same number of exposures brighter and darker on either side of the optimum exposure. Also, if doing it manually, you will have to put the camera on full manual for exposure, then set your aperture where you want and vary the time for the brackets.
The reason for bracketing is that the latitude for digital images is about 5 stops with detail and no digital “noise.” When lightening darker areas in a digital image, one sometimes runs into noise, either color noise which looks likes flecks of red, green, and/or yellow in that area, or luma noise, which looks like flecks of black snow. Noise is usually unacceptable in commercial work and for stock images. The answer is to bracket and take images in which even shadow areas are light enough to have detail without the need to lighten them, and to blend them into the finished image, either with HDR or layering and masking in computer-editing software. Conversely, blown-out areas of one image can be recovered from a darker bracketed image, and give detail to blown-out areas.
In summary, bracketing with available lighting or with hot lights is basically the same, and white balance should be checked and adjusted should the need arise.
-Gary Silverstein
