Metering and Compensation


Today’s Question: Can you cover how to shoot a snow scene to avoid blown highlights?

Tim’s Quick Answer: Other than checking the histogram to confirm you haven’t lost highlight detail due to over-exposure, when photographing a scene with snow it can be helpful to meter directly off the snow and increase that exposure reading by about two stops for snow in full sun and by about one stop for snow in shade or under a full overcast sky.

More Detail: The meter in your camera can be thought of as trying to make whatever you meter off of have a brightness value of 50% gray. If you meter off of a gray card, that works pretty well. When metering off a general scene that can be a little tricky, and it can be especially challenging when there is snow in the scene.

In general, you would not want the snow in a scene to appear with a luminance value of middle gray. But there is also a risk of snow being blown out in a scene, especially if the snow represents a relatively small portion of the frame. For example, if the scene is mostly dark trees with small areas of snow, the camera will likely brighten the exposure based on the dark trees, possibly losing detail in the areas of bright snow.

You can obviously check your exposure after the capture by using the histogram display, for example. However, you can likely get more consistent and accurate exposures in this type of situation by metering off the snow in the first place and compensating for the exposure accordingly.

If the area of snow is relatively small in the frame you may need to switch to the Spot metering mode for your camera. You can then meter off the snow, which would result in an exposure where the snow appears quite dark. To compensate for the fact that the snow should be much closer to white than to middle gray, you need to increase the exposure based on the metering.

For snow in full sun, you will generally get a good exposure by increasing the exposure by two stops compared to the metered value. If the snow is in full shade or the sky condition is full overcast, increasing the exposure by one stop will probably suffice. You may need to fine-tune to get the best exposure, but this approach will work quite well most of the time.