The above 3 areas taken together contain 4 2/3 stops.The histogram for shot #2654 is aligned with the last divider, and thus the third area includes 1 2/3 stops.
The histogram for shot #2645 is aligned with the first divider, thus the first area includes 1 2/3 stops.The histogram for the leftmost shot on the figure above, #2640, is very close to the right wall, and the entire image blinks on the LCD screen.Top row: Luma histograms of respective shots bottom row: Luma+RGB histograms.Īs you can see on fig.2 above, the histogram field is divided into 4 areas, and we have five vertical lines: left wall, 3 dividers, and right wall. If you are shooting RAW, JPEG will be embedded into the RAW file and used for previews and histograms.įigure 2. If you are shooting JPEG, RAW data will be discarded. All digital cameras always capture RAW data, and render a JPEG based on that data and camera settings. Please keep in mind that the histograms your camera displays are from JPEGs, even when you are shooting RAW. The lens hood nearly touched the diffuser, the lens was focused on infinity. The target was a simple halogen bulb in a reflector (you can use a LED panel, just make sure it doesn't flicker), diffused with 3 layers of heat-resistant white translucent fabric (the type used for softboxes, umbrellas, shooting tents.), placed approx. The exposure was set in such a way that the entire first shot "blinked" on the camera LCD, while the next shot, exposed 1/3 of a stop lower, did not.
In an attempt to put some numbers to those graphs, we took a series of shots, spanning over 10 1/3 stops, decreasing the exposure (increasing the shutter speed) by 1/3 of a stop for each consecutive shot. The problems with presentations like the one above is that they tell us nothing about exposure per se, they aren't in any familiar photographic terms, and that's not even mentioning that "very dark" or "very light" is about brightness, not about exposure.