Monthly Archives: November 2026

photography

Auto Focus Bother

The second of three Norfolk Southern unit coal trains was closely following the first, running on yellow (approach) signals.

We waited at Washington Boro, Pa., as the train approached. Unfortunately, the bright headlights confused the autofocus on my Nikon Z6-III, which I had set to AF-S instead of AF-C.

The difference is pretty straightforward. In the AF-S setting, there’s an interlock, and the shutter will not release until the camera’s autofocus has locked on to the selected subject. When the autofocus sensor was confused by the headlights, the shutter would not release.

No problem with the camera in AF-C autofocus here.
The train was only rolling along at about 15mph here, but the bright lights were making it difficult for the autofocus to lock-on to the lead locomotives. I was hoping the make a closer photo, but the autofocus got confused and the nechanism twirled through the full focus range without selecting a meaningful focus point.
Now this was a bother! The autofocus system in AF-S mode wouldn’t allow the camera to release the shutter and by the time the autofocuse system regained its lock on the subject, the lead engine was leaving the frame.
Here’s a trailing view of the same train. The camera’s autofocus system worked well in this direction. Lead locomotive 4822 was dressed in an unusual variation of the Norfolk Southern paint scheme, which includes red-orange striping at the ends of the engine.

While I eventually got the focus problem sorted out, the coal train was still rolling.

Despite this frustration, soon we were on the move after yet another nocturnal coal train on Pennsylvania’s Port Road Branch. When I had a moment, I fixed my AF settings.

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