If you really and truly want to know whether one camera has greater usable dynamic range than another, do this:
- Set up a target and meter it. Ideally, choose an f-stop around 1/4 - 1/10 sec to give yourself lots of room on both sides of the middle -- at least five stops above (longer shutter speeds) and at least 8 stops below (shorter shutter speeds).
- Set the camera to its lowest ISO, lowest contrast, WB appropriate to the light source, and make small jpeg files.
- Shoot a series of exposures from the camera's highest shutter speed to about 8 stops beyond the metered exposure (e.g., 4 - 6 seconds)
- Copy all the pix onto your computer and load your image-processing program (the gimp, Photoshop, etc.)
- Load all the images you can into this program, then use the curves tool (in color) or the eyedropper tool (in monochrome) to measure the pixel intensity of each image.
- Note visually which dark image first has "unusable" noise.
- Note visually which light image last has texture.
- Use your favorite spreadsheet program to record these values versus the relative exposure,
- Repeat this exercise with the other camera, and record its values in your spreadsheet in a second column
- then create a line chart of these values.
- Count the stops between the darkest usable image and the brightest with texture, and between that and pixel saturation.
This is the usable dynamic range.
It's actually pretty fast; about 10 minutes for all the exposures and a couple of hours for the post-processing.
For an example chart:http://www.danlj.org/~danlj/photos/techniq...amicRange2b.jpg