Tuesday, June 03, 2014

Using an action camera for model railroad video, part 2

In a previous post, I introduced the Sony HDR AS15 and discussed more general aspects of using the camera for filming on a model railroad layout.

This post focuses on camera orientation and point of view.

Since the body of the AS15 is symmetric it can be placed into the cradle normally, or upside down. There are distinct advantages to each placement.

AS15 right side up
When placed with the lens at top, the vantage point of the recording is obviously fairly high above the track. You get the effect of what an engineer of a Turbotrain, a modern US diesel locomotive, or a DB VT601 TEE train might see. This orientation also tends to be useful for showing off scenery around the tracks, or look backwards over a train of open gondolas or hoppers. I recorded the Welztalbahn trip as well as the pass through Tracy at Silicon Valley Lines with the camera set this way.

AS15 upside down
On the flip-side (literally), setting the lens low puts the camera at eye level of passengers in single level passenger cars, as well as matches the view of the engineer of a DB Schienenbus, which sits fairly low on the rails. A nice side-effect is that this puts the viewer much more in the action. This worked out nicely in the video of UP 844 in Kalamazoo at Silicon Valley Lines where I'm pacing the engine on a parallel track. Video recorded this way needs to be flipped in editing.

Given the very compact dimensions of the AS15, one can set camera at an angle on the flat car.

Camera set at an angle
This works particularly well when pacing a train, but one needs to pay extra attention to line side details like signal bridges or signs along the track. While setting up for the UP 844 shot, I sent the camera to the ground and mowed over a sign or two, which is why the rear part of the cradle's styrene base is now cut at an angle ...

The following two photos show the difference of the setup.

Pacing a train with low lens. Looks nice on screen.

Same setting but with lens at top. We can see more scenery, but also the roof of the Schienenbus.
A note on depth of field: The AS15 produces a sharp picture starting at about 3 inches from the object. If you get closer, things will get blurry (as can be seen in the UP 844 video).

The AS15 has two angle settings for the recording: 120 degress and 160 degrees. For model railroad video I always use 120 degrees, because vertical objects such as buildings, signal masts, etc. get badly distorted when the train is passing by with the angle at 160 degrees.

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