what parameters affect exposure latitude in digital cameras? What would one look for to be able to expose for bright sky and dark foreground?
Wrong Forum, but offhand, I'd say it would depend on the results that the exposure algorithm arrives at from the pixel percentage of the bright and dark parts of the scene. It is sometimes camera - specific. See your camera manual for details of its light measuring pattern.
As a rule of thumb, it's better to expose for the lighter parts of the scene, as it is easier later on to lighten the dark parts than to recover the burnt ones.-- hide signature --
Other things to look for would include dynamic range enhancing features. Some brands use an application of Apical's Iridix technology which, "applies pixel-by-pixel tone curve adjustment automatically to pull out detail simultaneously from shadows and highlights while leaving midtones untouched." This helps render a scene more like the human eye would have seen it. Olympus now calls it Shadow Adjustment Technology and is applied by setting auto gradation in the menu. Nikon calls it Automatic D-Lighting.
Another strategy is to take two or more exposures, with one exposure designed to capture detail in the shadows while another retains highlights. The exposure are then merged into one image that avoids blown highlights and blocked-up shadows. Many cameras can do this automatically; some recommend using a tripod while others can be used successfully hand-held. This technique can be problematic with fast-moving subjects since the exposures are taken successively, not at the same time.
Fuji, using the DR (wide dynamic range) mode of its EXR sensors, is able to divide the pixels on the sensor into two groups so the multiple exposures are taken at the same time, though this halves the resolution capability of the sensor. "With one press of the shutter button, the sensor captures the scene at high sensitivity and low sensitivity and then combines the data into a single image with Wide Dynamic Range up to 1600%. Even when shooting moving subjects, which is not possible with conventional multi-frame capture and processing, DR powered by EXR overcomes highlight "washout" and shadow "blackout" to reveal smooth natural tonal quality."
I've used all of these features in various Olympus, Nikon, Ricoh, and Fuji cameras, and all of them, while not perfect, are a help in high-contrast situations. For the particular situation you mentioned of bright sky and dark foreground, the split neutral density filter also remains a possible solution.
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