Optical

• 114 mm primary mirror (700–900 mm focal length)
• 5-inch PVC pipe

Electronics

• Raspberry Pi Zero 2 W
• Raspberry Pi Camera Module
• Pi Zero camera cable
• 18650 Li-ion battery
• 5 V boost/charge module
• MicroSD card
• Push button

Hardware

• 3D printed parts
• Compression springs
• M8 hardware
• M5 threaded rod
• M2 hardware
• Self-tapping screws
• Double-sided mounting tape

All CAD STL files are available in the Astra GitHub repository.

Measure the actual inner diameter of your PVC pipe before printing anything.

PVC pipes are sold using nominal dimensions, so my "5-inch" pipe actually measured about 5.25 inches internally. I modified the original PiKon models to match.

I also redesigned several components:

• Electronics mount
• Universal tripod mount
• Smartphone holder
• Rack-and-pinion camera focuser

Print the parts using PETG or ABS. PLA can soften in hot weather, potentially affecting optical alignment.

For the tube itself:

• Cut it slightly longer than your mirror's focal length.
• Line the inside with matte black paper or paint.
• Paint the outside if desired.

Since a telescope depends on precise alignment of its optical components, dimensional accuracy and print quality are especially important. That's where Justway comes in.

Beyond 3D printing, Justway also offers CNC machining, sheet metal fabrication and injection molding making them a great option for both hobbyists and professional product development.

What makes Justway stand out is its broad range of manufacturing capabilities available through a single platform. Whether you're ordering a one-off prototype, validating a design, or preparing for larger-scale production, you can manage the entire process with one supplier. The company also offers an online quoting system, engineering support, production tracking, and a wide selection of materials and surface finishes, making it a convenient option for projects of all sizes. If you're looking for a manufacturing partner that can support a product from prototype to production, Justway is worth considering.

A big thank you to Justway for supporting this project.

Remove the Raspberry Pi camera lens so only the bare sensor remains.

Disconnect the sensor board, then carefully unscrew the glued lens assembly with pliers.

Begin by assembling the two optical modules.

The mirror cell uses three bolts and compression springs to provide collimation adjustment.

The spider assembly holds the rack-and-pinion focusing mechanism and camera mount.

Install the spider into one end of the tube and mount the electronics plate.

Attach the camera module using M2 bolts and nuts.

Mount the primary mirror only after the rest of the telescope has been assembled to reduce the chance of accidental damage.

Before fixing the tripod mount permanently, temporarily install the mirror assembly and balance the telescope to determine its center of gravity.

Mount both the tripod adapter and smartphone holder at that location.

The telescope is powered using a single 18650 Li-ion cell together with a 5 V boost/charge module.

This makes the entire telescope completely portable.

Mount all electronics onto the printed electronics plate using double-sided tape.

Connect:

• Raspberry Pi Zero 2 W
• Camera module
• Battery
• Boost converter
• Power switch

A protective electronics cover completes the assembly.

Flash Raspberry Pi OS Lite (32-bit) to the microSD card using Raspberry Pi Imager.

Configure:

• SSH
• Wi-Fi
• Hostname
• Username/password

A detailed software installation guide, Python application, and web interface source code are attached in the attachments section.

The software provides:

• Live MJPEG video streaming
• Moon, Planet, and Deep Sky presets
• Exposure and gain control
• Image capture
• Digital zoom
• Browser-based control from any phone

Attach the telescope to a sturdy photography tripod.

Power it on and wait about one minute.

Connect your phone to the Astra Wi-Fi network and open:

http://astra.local

The browser-based interface displays the live camera feed and imaging controls.

For pointing the telescope, attach your phone to the integrated phone holder and use an astronomy app such as Sky Map or SkEye.

Once the target is centered, adjust the focus wheel until the image becomes sharp.

If necessary, fine-tune the primary mirror collimation using the three adjustment bolts.

Despite being tested from my apartment balcony during Bangalore's monsoon season, Astra successfully captured detailed images of the Moon and its craters.

Under darker skies and steadier atmospheric conditions, significantly better planetary and deep-sky images are possible.

Compared to similarly priced commercial telescopes, Astra offers a much larger aperture while adding digital image capture, wireless control, and complete portability.

More importantly, building it was an excellent way to learn about telescope optics, mechanical design, Raspberry Pi programming, and astrophotography.