Tag Archives: difficult exposure

photography, Tips and Technique

Metrolink 115 at Simi Valley, California; a difficult exposure.

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Here’s an exposure quandary. A bright white Metrolink F59PHI in blazing California afternoon sun against a varied background of trees and mountains..

Metrolink's scheduled train 115 accelerates away from its Simi Valley station stop in July 2016.
Metrolink’s scheduled train 115 accelerates away from its Simi Valley station stop in July 2016.

Without careful metering and a bit prior experience It would be easy enough to underexpose a photo like this one. (Producing a result that is too dark)

Why? Because the camera meter doesn’t know the locomotive is white, and if relying on many auto exposure settings, metering tends to over compensate as the white engine reached the center of the frame.

On the flipside, the row of trees at the left could fool also the meter into compensating for the relative darkness and thus producing an image that is too light overall with the front of the engine grossly over exposed.

What’s the solution?

Before the train comes into view, make a series of test meter readings while aiming a sunlit neutral portion of the scene such as the ballast. Then observe the relative difference in exposure between lighter and darker areas, make a test photo or two, and if your camera has a histogram check to ensure that the bulk of the exposure is in the center of the graph. Then set the camera manually based on this information.

In my situation, I made a slight adjustment as the locomotive came into view to compensate for the bright white nose section. This meant I needed to stop down (see the aperture to let less light in) by about 1/3 of a stop.

Here's the Jpg of the train along site the camera's EXIF data. The relevant fields show that the camera was set at ISO 200; shutter speed 1/500th of a second, and the lens was at f7.1. So why not f8? That would cause the trees to become too dark and the engine appear more gray than white.
Here’s the Jpg of the train along side the camera’s EXIF data. The relevant fields show that the camera was set at ISO 200; shutter speed 1/500th of a second, and the lens was at f7.1. So why not f8? That would cause the trees to become too dark and the engine appear more gray than white.
Here's my closer view. I retained the same exposure setting.
Here’s my closer view. I retained the same exposure setting.

In both photos, other than scaling for internet presentation, I did not alter the files in regards to exposure, contrast, color or sharpness. These images represent reduced versions of the in camera JPGs (althouth I simultaneously exposed RAW files as well.)

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