Reflective Telescope

This guide will explain how you can make your own Newtonian reflector telescope. This telescope can be utilized to observe anything from an island off the coast of your closest beach to distant celestial objects. Our design focuses on an easy-to-adjust frame that allows you to easily adjust the focus and FOV, allowing for high-quality pictures and viewing. Above, you can see a photo of our final product, and an example image was taken approximately 250 meters away.

The most important pieces required to build the telescope are the primary and secondary mirrors. You can obtain these on most hobbyist telescope websites (an example is pictured above). Depending on the focal length and size, you will have a different level of magnification and FOV. You will also need either an eyepiece of a camera (or both!) to be able to see through your telescope.

For actually building the telescope, we highly recommend using 80/20. 80/20 is a highly customizable set of building blocks that you can easily use to build the frame and the base of the telescope.

Here is a list of supplies that you will need:

• SVBONY SV135 7-21mm 1.25" Zoom Eyepiece
• Secondary mirror
• Primary mirror
• SVBONY SV105 Telescope Camera
• J-B Weld EpoxyA
• ~15cm x 15cm piece of the acrylic plastic plate
• ~25x sets of screws
• ~33x corner brackets
• 4x pieces of 1.6m 80/20
• 8x pieces of 16cm 80/20
• 4x pieces of 1m 80/20
• 1x piece of 12cm 80/20

For the rest of the guide, we will explain the exact process of building one of these telescopes using all the materials pictured above.

First, we need to get familiar with how a reflective telescope works:

Distant light enters the telescope from the opposite side of the primary mirror and is focused by the primary mirror. It then reaches the secondary mirror, which directs the light to the eyepiece.

The optics we are using in this particular design are as follows:

• Primary (Spherical) Mirror: focal length (f_p) 900mm, aperture (d) 144 mm
• Secondary (Flat) Mirror
• Camera: equivalent to a raw retina (without lens)
• Eyepiece: focal length (f_e) 7-21 mm

From such conditions, we can work out the following characteristics of the telescope:

• Apparent Field of View (AFOV): 40 degrees
• Resolution: 1.3 arcsec
• Magnification (M): f_p/f_e = 60
• True Field of View (TFOV): AFOV/M = 0.67 degrees = 2412 arcsec
• Light Gathering Power Compared to Naked Eyes: d/7mm = 265 times

For this step, we need: 8x corner brackets; 4x set of screws; 4x pieces of 16cm 80/20; 4x pieces of 1-meter 80/20

In this step, we will build the main frame for the telescope. To do so, we will first create a square with the smaller pieces attaching them together with corner brackets on the inside of the square. Make sure to leave an extra length of 80/20 on each side of the square (as shown above). We then attach the longer pieces (the main pillars of the telescope) to each corner of the square, using the extra length of 80/20 to attach the corner brackets.

Additional structure of the telescope will be attached to this frame.

The dimension of the square base is subject to the diameter of the primary mirror. The length of the pillars is subject to the focal length of the primary mirror (the length of the pillar must be at least longer than the focal length of the primary mirror to ensure that there is space to attach the secondary mirror and the eyepiece).

For this step, we need: J-B Weld Epoxy; the primary mirror; a ~15cm*15cm piece of the acrylic plastic plate.

Once the frame is well constructed, the primary mirror should fit directly onto the base. We first cut out a piece of acrylic plastic so that it fits onto the base. We then used the "J-B Weld 8265S Original Cold-Weld Steel Reinforced Epoxy" to attach the mirror on the plastic plate and the plate to the frame.

This plastic plate ensures that the contact area between the mirror and the base is maximized.

For this step, we need: 3 corner brackets and 4 sets of screws; 1 piece of 12cm 80/20; the secondary mirror

First, we want to secure the 80/20 on the middle of the eyepiece holder with a corner bracket so that the bar is centered (in and out of the page in the first picture). We then slide the 80/20 in the vertical direction in the first picture so that the bar's edge is also centered. We then join the mirror with the bar by connecting it with two pieces of corner brackets - this naturally creates the 45-degree angle we want.

For this step, we need: 12 corner brackets, 12 sets of screws, 4 pieces of 16 cm 80/20, the camera, the SVBONY SV135 7-21mm 1.25" Zoom Eyepiece

For the sake of alignment, it is best if the eyepiece/camera is on the same structure as the secondary mirror.
Two pieces of 80/20 are attached to the main pillars of the telescope with brackets with the secondary mirror holder attached to one of the pieces (as shown above). The other 2 pieces of 80/20 can be optionally attached to the previous 2 pieces to provide 2 convenient handles for the user. In between the 2 pieces perpendicular to the main pillars of the telescope are 4 brackets used to create 3 points of contact (shown in red above) to secure the eyepiece/camera. Note that our eyepiece and camera have the same radius (additional adjustments are necessary if they have different sizes).

When looked at from above, the camera/eyepiece should directly look into the secondary mirror (as shown above).

To adjust the light path and, in turn, adjust the focus, we can loosen the screws of the 80/20 to allow the whole structure to slide on the main pillars of the telescope.

Now we can calibrate the telescope so that the primary mirror, the secondary mirror, and the eyepiece/camera can align perfectly. A simple step to do this is to cut a piece of paper into a circular shape so it fits on the eyepiece. We can then poke a hole through this piece of calibration paper, put it on the eye piece, and look through the hole. This piece of paper ensures that the light rays will be going through the eyepiece parallel.

If you have done this correctly, you will be able to see something similar to the first image of the following picture, and our goal is to make it look like the last one.

Looking through the calibration paper, you will see the secondary mirror, a reflection of the primary mirror, and a reflection of the eyepiece. This can be a little challenging at first to identify all of the parts, so take your time!

Once you have identified all of the pieces through the calibration paper, you can first try to move the secondary mirror around so that the reflection of the primary mirror is centered just like the second image. Then, you can try to adjust the primary mirror if the eyepiece is not centered (the eyepiece should be already centered if the primary is well-aligned).

After all these steps, if every optical piece is centered in your field of view, the telescope is well-aligned, and you are ready to observe!

We used the SVBONY SV105 Telescope Camera, which replaces the eyepiece. However, one significant difference between the camera and the eyepiece is that they have different focal lengths. As illustrated in the picture, we want the light rays coming out of the eyepiece to be parallel so that our eyes can focus the light on our retina. Meanwhile, we want the light rays to be focused on the camera, so it forms an image. This requires us to adjust the eyepiece holder and the secondary mirror slightly when interchanging the eyepiece and the camera.

We used software called AstroDMx, which is really easy to navigate. After connecting your camera to the computer, you can click on the "connect" button and choose the camera you want to use under the "Camera" tab. You can also choose your desired format and resolution. After connecting, you will be able to see a continuously updated image of what the camera is capturing. You will be able to change the exposure time, contrast, saturation, etc. Depending on the type of object you are observing, these values should be changed accordingly.

After the telescope is focused on your target, you can click on the "capture" button, which captures the images continuously until you hit the "stop" tab. You will be able to save the image as different file types. We saved our images mostly as .fits and .png files for easy visualization and editing.

We have also attached a python file that can be utilized to average many pictures you take of an unmoving object. This can help remove noise that can be present in each individual image. NOTE: This will only work for stationary objects as the noise in tracking a moving object will cause parts of the object to be filtered out.

For this step, we need: 10 corner brackets and 4 sets of screws; 4 pieces of 1.6m 80/20

Constructing the base is completely optional; one can tilt the telescope on any ramp or structure to aim the telescope; however, the base provides easy support and rotation for the telescope and prevents contact of the main structure with the ground, which may shatter the primary mirror.

We first set 2 long pieces of 80/20 on the ground and connected the other 2 long pieces of 80/20 to the telescope's main structure with brackets and screws (as shown above). Note that 80/20 on the ground must be longer than the pillars of the main structure to ensure its stability.

Use only one bracket between the base pillar and the main structure pillar to allow the telescope to be tilted at any angle. Further 80/20 can be added to the base pillar to provide further enhancement.