Intro: Make a Red Head-torch for Astronomy - Under $10
Getting a glimpse of the night sky on a budget can be difficult, my cheap refracting telescope has a hard time taking enough light in from distant sky objects as it is, improving your own vision at night by using a red light is a great way improve your amateur sky gazing experience. A red light can help you see what you're doing in the dark, without ruining your night vision, this interesting article explains how. During this indestructible, we'll modify a head torch and ruin some 3D glasses to make our own red light for under $10.
Step 1: What You'll Need:
A cheap one I picked up for $5 at a discount store.
3D Anaglyph Glasses:
Bought this off eBay a while ago, available Here. The cardboard ones should work just as well.
1.5mm Drill bit (And a drill to use it in):
We'll be using this to drill out the part of the red filter that we'll need, if you have a dremel (which I don't), I'd recommend using that.
A pin or anything else that can mark plastic will also work.
Step 2: Disassembling the Head Torch
Pulling the front of the torch away from the body will free the lens housing from the base of the torch.
The lens housing can then be unscrewed to reveal the white piece of plastic that the LED sits in. We'll be using this to mark out the red filter from the 3D glasses in the next step.
Step 3: Marking the Red Filter for Cutting
First, pop the red filter out of the glasses frame by simply pushing it out from the inside.
Use the white piece of plastic we got from the lens housing in the previous step to trace a circle on the lens, using the utility knife.
Step 4: Cutting Out the Red Filter
Using the 1.5mm drill bit, drill holes around the circle previously marked.
The circular piece of red filter can then be pushed out with your fingers.
Step 5: Cleaning Up the Edges
I smoothed out the jagged edges of the red filter using a grinding stone in the bench drill, though a hand file or coarse sandpaper may also work. It doesn't have to be perfect, as the light from the torch will only pass through the center most part of the filter.
Step 6: Reassembling the Head Torch
First, drop the white plastic piece back into the bottom part of the lens housing, followed by the red filter on top of that, then screw the top portion of the lens housing back on.
Now push the whole lens assembly back over the base of the head torch (you should hear it click into place), and Voila!
Step 7: All Done!
Now you can see and control your telescope, without blinding yourself to the beauties of the night sky.