Bright sunlight bouncing off sandstone can easily fool a camera’s built-in light meter. Highly reflective sandstone (or bright snow) will usually cause your camera to underexpose, in the “Auto” mode, giving you a dark photo. Slightly overexposing bright sandstone may capture the tonal values more as your eyes see them.
For better photos, switch to “Program” mode (P), so you can make customized adjusts to exposure. Review the last few photos on your LCD screen. Too dense and heavy? Or overly pale and pasty? Time to take control of your camera and get a custom exposure!
Most cameras have an external button with a tiny (+/-) symbol for the “Exposure Compensation” function. Press the button and you will be ready to make adjustments. (Note: This function in accessed in different ways depending on your camera brand.) Once the function is activated, move the indicator toward a minus number (-0.3, -0.6, -1.0, etc.) to get a darker photo. Use the plus numbers (+0.3, +0.6, +1.0, etc.) to get a brighter photo. Review your last shot and adjust accordingly. Experiment until your photo feels “just right.”