Saturday, August 15, 2009

HDR Guidelines Part 2


This is part 2 of Bull's HDR guidelines here at LIGHT.

Camera
-Manual mode
- ISO: 100 Canon / 200 Nikon
-Constant Aperture = vary shutter speed only
-Constant White Balance
-Continuous shooting drive mode – high if you have it
-Focus – One shot or one time.
-Use AF to assist and either hold AF-On button continuously through the shots or switch to manual focus after focus lock is achieved.
-Shoot RAW
-Use auto exposure bracketing (AEB) functionality as much as possible
-Know your camera’s capes and lims
-Use +/- 2 EV jumps (new Nikons only have 1 EV jumps available)
-Some scenes may use +/-1 EV for better results

How Many Shots?
-Depends on the scene’s dynamic range (DR)
-Meter the highlights and shadows and determine the difference between the two in stops
For example, with a constant aperture and ISO the highlights are exposed properly at 1/8000 and the shadows at 1/15, there is a 9 stop difference.
-Shoot the required number of shots at your desired interval. In our above example, take nine shots 1 EV apart or 4-5 shots 2 EV apart (sometimes even with a 9 stop difference as above you can cover with a three shot sequence at 0, +2, and -2 EV)
-Use AEB to capture the full range for increased efficiency.
-First shot determines the starting point of the full DR captured with your series of shots
-In the example above (highlights at 1/8000 and shadows at 1/15,) full stops between are shown below. 1/500 is the center point of the dynamic range. Only whole stop increments are depicted. Each green bar shows one shot and the associated range.




-We arrive at the efficient method by shooting our first shot in the middle of the range and then shooting two addition images at +2 and -2 EV. New Nikons will need to shoot 5 images at the max 1 EV spacing to generate the 9 stops of usable data.
-Biasing the initial capture EV will skew the range as well.

-AEB may be used in series to expand range even further
-For example take first 3 shots at -2, -4, and 0 take second three shots at +2, +4, and 0
-Total range will be 13 stops of data (-4 to +4 = 8 stops plus 2.5 usable at each end.)


Part 3 next week.


Fiat Lux!

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