DIY Red-light Head Light

You might ask, "Who would want a red-light head light?" Well, amateur astronomers, for hands-free seeing at night, especially if they're carrying or handling equipment, such as telescopes. Other night-sky observers might want to wear them for being able to walk around without bumping into people or items, and they can retain night vision while viewing objects, whether through telescopes or binoculars at night-sky watching events.

You might wonder why it's important to use red light at night to see with instead of using other-color light. Red light helps illuminate dark areas without adversely affecting night vision. Eyes need time to adjust to dark surroundings. At night, when someone turns on a non-red light, such as car headlights or white-light flashlight, sky objects become less visible and vibrant until the eyesight becomes re-accustomed to darkness.

A red light head light is a modification of an off-the-shelf elastic headband lamp. (More on acquiring the lamp and similar later.) The bulb itself is white—suitable for normal uses. For astronomy purposes, the light needs to be red.

Step-by-step Modifying Regular Headlight to Red Headlight

The video shows items needed, procedure, and white lightcircle next to red light circle. Items required:

• Head lamp (Western Safety brand) or similar elastic-band lamp with center bulb
• Red automotive tail light tape, available at auto parts stores
• Scissors

Note: The tape should be wider than the diameter of the lamp's screw-on transparent cap. For example, the tape I used was 1 7/8" wide, and the cap was 1 5/8" across. (Ruler in video is for tape width reference.)

Procedure

1. Unscrew the retainer ring with clear cap from the rest of the lamp.
2. Separate the clear cap from the ring.
3. Cut a squarish piece of red tape that overlaps the cap with a reasonable margin all around. In my case, the tape was wider than the cap diameter by only 1/4".
4. Firmly place the center of the flat part of the cap onto the sticky part of the tape.
5. With scissors, snip the red tape's corners and sides up to the cap's edge.
6. Fold and evenly press each of the snipped tape corners to the cap's edge, pressing at opposite corners for evenness in stickiness and surfaces.
7. Press the retainer ring back onto the cap.
8. Screw the retainer ring and cap onto the lamp.

For contrast, the video shows red and white flashlight circles side by side.

Getting an Elastic-band Headlight

Western Safety manufactures a headlamp commonly available at Amazon and Harbor Freight. Amazon's price is $1.79, and Harbor Freight's list price is $2.99. For additional types of headlamps, visit Google image offerings.

Some Caveats of the Western Safety Headlamp

You might run into at least one of the following situations if you get headlamps that this company manufactures. The first two items have workarounds.

• Slots for straps might be wide; straps might loosen from the unit. (Tape the strap pegs together.)
  
  
  
  Related: Contrast two styles of strap retainers and slots.
  
  
  
  
• Straps might be short (tight fit) for the wearer. (Stitch an extender, such as a piece of a lanyard or wide ribbon.)
  
  
  
  
• Switch sometimes doesn't turn on reliably.
• Battery cavity can be slightly undersized and batteries not fitting well.