Understanding and Using Dynamic Range Eagle River Camera Club October 2, 2014
Dynamic Range Simplified Definition The number of exposure stops between the lightest usable white and the darkest useable black the camera can capture in a single image. A function of the camera s sensor Varies with Age and manufacturer of camera Size of sensor (APS-C, Full Frame.) Size of sensor photosites File Format (JPG, RAW, TIFF ) ISO setting (decreases as ISO increases)
Camera vs Human Eye 7 14 stop dynamic range Bad at white balance determination Excellent color rendition in low light Single aperture setting per image Sees entire scene simultaneously Collect light over time to create images in near darkness 24 stop dynamic range Continuous white balance adjustments Poor color perception in low light Rapid iris adjustment as the scene is viewed Sees scene in pieces and assembles vision in brain Can only use the light available at that instant
Dynamic Range Example 1 Dark with 11 Stop Dynamic Range Bright with Dark with 24 Stop Dynamic Range Bright with
Dynamic Range Example 2 Dark with 11 Stop Dynamic Range Bright with Dark with 24 Stop Dynamic Range Bright with
Dynamic Range Example 3 Dark with 11 Stop Dynamic Range Bright with Dark with 24 Stop Dynamic Range Bright with
Dynamic Range Shortfall This scene exceeds the dynamic range of the sensor Exposure was a compromise No detail in highlight areas Bright areas tend to be slightly overexposed, appear washed out No detail in deep shadow areas
Determine Camera s Dynamic Range Trust the manufacturer s specifications Look it up on a trusted website DxO Mark: http://www.dxomark.com They have tested most DSLRs Test using special software Imatest Studio ($300): http://store.imatest.com Do your own test using a DIY technique
DIY Technique 1 Very basic, only good for JPG images The Set Up Set camera in manual exposure mode Use spot metering mode Set aperture to f/8 and ISO to 100 or 200 Turn off autofocus Enable highlights or over exposure warning Place a plain sheet of white paper at a 45 to the lens about 3-4 inches from the lens Make sure the illumination on the paper is as even as possible. Adjust the shutter speed until the light meter registers in the middle or centered and take a photo. The histogram should show a narrow spike in the middle of the chart. Slow the shutter an additional 7 stops (21 clicks)
DIY Technique 1 The Test Take a photo and go to the review mode You should see a narrow spike on far right of the histogram Most or all of the screen should flash in the highlights Speed the shutter up 1 stop (3 clicks), take another photo & review it Continue this until the first setting where most of the highlight screen is not flashing Write down this shutter speed Continue to speed up the shutter 1 stop at a time, take a photo and observe the histogram Do this until the spike in the histogram touches the left side of the histogram chart Write down this shutter speed Calculate the stop difference between the two shutter speeds. This is the rough dynamic range when shooting JPGs. You can estimate a two stop increase in this range for RAW.
DIY Technique 2 Find a uniformly lit and colored textured surface. You want this wall medium grey or as close to this as possible. Get as close to the chosen surface as possible so that you see only this surface in your viewfinder. You don t want anything else in the photograph. Set ISO to 100 or 200. Set the aperture to F/8. Adjust the shutter speed to achieve a correct exposure; the light meter is centered Speed up the shutter to take a series of underexposed shots; one stop, two stops, three stops, four stops, five stops, six stops, and seven stops. Slow the shutter to take a series of overexposed shots; one stop, two stops, three stops, four stops, five stops, six stops, and seven stops. Import your raw files in your raw converter and do not adjust the exposure compensation whatsoever. Simply convert the images and open them in your image editing software. You should have 15 images. One exposed correctly, 7 overexposed and 7 underexposed. What you are looking for are images that are either so light or so dark that they do not show any detail or texture. Once you have determined the images that have detail in them count them and subtract 1 to determine the dynamic range. If you have 12 images showing details your digital sensor is able to record an 11-stops range.
Determine Tonal Range of Subject Use manual exposure mode Set camera to Spot metering Select darkest portion of the scene that matters to your final image Adjust shutter speed until the camera s light meter indicator is centered (in the middle) Remember or note this value Select brightest portion of the scene that matters to your final image Adjust shutter speed until the camera s light meter indicator is centered (in the middle) Remember or note this value Determine the stop difference between the two shutter speeds
Select Scene and Determine What Matters Cloudless Sky Sun Shadow Side of House Ground
Meter Darkest Part of Image that Matters
Meter Brightest Part of Image that Matters
Determine the Stop Difference Measurements 1/30 second = Darkest 1/500 second = Brightest Calculate Difference 1/30 to 1/60 1 Stop 1/60 to 1/125 1 Stop 1/125 to 1/250 1 Stop 1/250 to 1/500 1 Stop Total 4 Stops
What to Do? Live with it as is & select the best exposure Use graduated neutral density filters to reduce the brightness of the sky Add light to darker areas with reflectors, flash, or other artificial source Screen light from brighter areas with scrims, screens, or diffusers Use a High Dynamic Range (HDR) shooting technique
Questions?