(This article originally ran in the April, 2013 Camera Bag column in Railfan & Railroad Magazine.
It has been updated for presentation here.)

Moon over the Southern! As part of the photo excursion "RGS 455 Returns" in August, 1997 on the Cumbres & Toltec Scenic RR, C&TS 463, relettered and numbered as Rio Grande Southern 455, was posed outside the Chama, New Mexico roundhouse for a night open flash photo session. The moon in this scene is from a prior exposure with a 400mm lens, as described in the text.

This technique involves multiple exposures on one roll of film and is best done with an older all manual film SLR without automatic film rewind, as you need to control the rewind process to leave the leader out for reloading and manual positioning of the film. Place a fresh roll of film in the camera and start the leader onto the take-up spool. Carefully tighten up the film with the rewind lever, and make a registration mark on the edge of the film next to some point in the camera, such as the edge of the film gate. Close the back and advance the film to the first frame.

Next, go out at night and shoot this roll on a full moon, or a nice crescent, using a tripod and a telephoto to emphasize the moon. The moon should be in a portion of the sky where no clouds will be included in the composition, and the sky is not bright from city lights. Be sure nothing else is visible, such as a foreground tree branch, a tall building, etc.

Shoot all frames with the moon near an upper corner of the frame, leaving some space toward the edges to avoid having the moon positioned over the edge of the frame when you make the second exposures. You can shoot a variety of compositions (horizontal, vertical, moon at the left, at the right, etc.), but keep notes of where you place the moon in each frame for later reference with the second exposure.

To properly expose the moon, use manual exposure mode and set exposure for full sunlight plus one stop. With ISO 100 film use f/11 and 1/125. For a crescent, open up two stops to f/5.6 and 1/125. After shooting the roll on the moon, slowly rewind the film being careful to leave the leader out of the cassette, by listening for the little "click" sound when the leader pulls free. Then start the roll through the camera again after lining up your pen marks as you did the first time. This insures each frame on the film will line up in pretty much the same position as the first time the film went through the camera, so your moon will appear in the correct position in the sky for the second exposure.

(To leave the film leader out with a camera with automatic film rewind, do not shoot the last frame, but open the camera back in total darkness, remove the film and twist the cassette end knob to manually rewind the film - except for the leader - back into the cassette. Close the camera back and activate the rewind function before reloading, else when you put the film back in it may be automatically rewound all the way into the cassette when you close the camera back.)

Now, go out in the daytime (or at night with lighted subjects) and experiment by shooting a variety of trains or locomotives. Use a normal metered exposure for this second shot. This 2nd, "multiple" exposure will capture your subject with the moon hanging above in the sky. (Be careful to allow enough sky above your main subject on the second exposure so the moon will not be "sitting" in or on your subject!)

With a 120 / 220 roll film camera, simply line up the arrows on the paper backing as you normally do when loading. However, after making your moon exposures, you will have to "re-spool" the roll back onto the now empty film spool by hand in total darkness, in order to re-start it through your camera.

Hanging the Moon Digitally
With a digital camera, the process to hang the moon is different. Rather than using a multiple exposure as above, you will have to use the Layers function in a computer image processing program (Photoshop described here) to add a moon from a separate image. In this case, open your train image, then also open a moon image. Using the Elliptical Marquee Tool draw a circle around the moon being careful to not let the selection include any of the adjacent sky, do a copy function, move back to the train image and paste the moon into the location you want above your train.

If this is a daytime train image, use IMAGE MENU > ADJUSTMENTS > LEVELS and move the mid-tone slider to the left to lighten the moon so it looks somewhat faded as it does in a real daytime sky. If pasting the moon into a night time train image, leave it fully bright. Flatten the layers and zoom in on the moon and clean up any varying tonal values in the sky around the moon (there should not be any if you made a proper selection.)

A full moon was digitally copied into this photo of an eastbound Union Pacific coal train on the Dotsero Cutoff in Colorado using the methods detailed in the text.

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