DIY Electronic Focuser | Reflector

I’ve built an electronic automatic focuser (EAF) for my Vixen R114 reflector for automated and precise focusing. The focuser was built with a geared stepper motor, A4988 stepper motor driver, and an Arduino Uno. It runs on the firmware developed by R. Brown (2021).

DIY Electronic Focuser for a Vixen R114 reflector

The focuser is ASCOM compliant and works with astronomy software such as the Nighttime Imaging N Astronomy (NINA) for automated focusing during unattended imaging. To watch a video showing the focuser’s movement, click here.

Related link: View all home-brewed DIY astronomy equipment

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

How to Image the Milky Way

In the Philippines, the Milky Way is most prominent in the sky during months of March to May each year, visible to the unaided eye in the southeastern horizon at around 1 to 3 am.

Milky Way in Coron

Any DSLR camera or smartphone with good camera may be used to photograph the Milky Way. To capture the Milky Way:

  1. Set the lens’ focal length to wide-field (18 mm). Milky way is a large target.
  2. Set the exposure time to 30 seconds.
  3. Set the aperture to widest opening (f/1.8).
  4. Set the ISO value to maximum (ISO 3200).
  5. Turn off the camera’s flash.
  6. Attach the camera to a tripod.
  7. Set the focus to manual mode.
  8. Focus on a distant target such as a star.
  9. Use the app Stellarium to find the Milky Way.
  10. Turn on the camera’s time-delay feature.
  11. When ready, press the shutter to take a photo.

Related link: DIY Sky Tracker

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© Anthony Urbano | Manila, Philippines

DIY Ultra-Portable Sky Tracker

Due to Earth’s rotation, objects in the sky appear to move from east to west. Taking a long-exposure photo of stars using a camera on a non-tracking mount will produce trails. To compensate for the Earth’s rotation, a tracker as simple as a geared stepper motor can be used. This tracker is controller by a simple Arduino-based stepper controller.

18 mm at 90 sec (animation)
Milky Way captured with an 18 mm lens at 90 seconds exposure, with and without tracking.

Any geared stepper motor with sufficient torque can be used as a drive mechanism. For this project, I used a stepper motor with a built-in 1:500 gearbox.

Ultra-portable tracker for DSLR cameras

I simply attached an aluminum plate to the end shaft of the stepper. A ball head mount was then used to connect a DSLR to the plate. All the components can fit easily in a small camera bag. It is designed to carry only a very light payload such as a DSLR with a wide-field lens.

Component parts of the DIY portable tracker

To test it further, I also tried it with a more demanding lens: 55 mm. Without tracking, stars appear as streaks, but with tracking, stars remain as fixed points.

55 mm at 120 sec (animation)
Milky Way captured with a 55 mm lens at 120 seconds exposure, with and without tracking.

Even with a 55 mm lens, the tracker is capable of accurate tracking up to 120 seconds, which should be accurate enough for Milky Way shots.

Calibrating the DIY Tracker

The tracker’s ‘tracking speed’ needs to match the actual movement of the sky. Calibrate your own tracker by making sure that the stepper does not rotate a bit too fast nor too slow. Align the tracker’s axis of rotation (or what is called the polar axis, which in this case, the stepper’s main shaft) with the north star Polaris (for observers in the southern hemisphere, point the tracker’s polar axis in the general direction of the Earth’s southern polar axis). Point the camera to any bright star. Turn the tracker on and start tracking the sky. Take a series of shots (with just enough exposure to capture the position of stars). By looking at the live view images or photos taken, you should be able to tell whether or not the tracker is moving too fast or too slow.

Polar Alignment

Before attempting this method, make sure that you have already calibrated the tracker, that is, you’ve managed to achieve a correct tracking rate. When pointed to a star in the east, minimize the north-south drift by adjusting the polar axis higher or lower (altitude adjustment). When pointed to a star in the celestial equator (near meridian), minimize the north-south drift by adjusting the polar axis to the left or to the right (azimuth adjustment). The east-west drift is corrected by adjusting the tracker’s speed.

This project has been featured in HACKADAY.

Related links:
DIY Telescope Clock Drive
DIY OnStep Go-To Telescope Controller
View all home-brewed DIY astronomy equipment

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

DIY Telescope Clock Drive

Clock drives are simple tracking mechanism that move a telescope’s RA axis one rotation every one sidereal day (23 hours and 56 minutes) to effectively compensate for the Earth’s rotation. It allows precise tracking of planets, galaxies, nebula, and other sky targets.

Telescope clock drive controller based on L293D and Arduino Uno board

An inexpensive Arduino Uno board and L293D-based stepper motor driver can be used to control a telescope. Attach a stepper motor on a telescope’s RA adjustment knob, then find the correct motor speed that will match the movement of the sky. Below is a sample sketch for a simple telescope clock drive controller.

//Simple clock drive controller by Anthony Urbano 06 September 2021. It uses an Arduino Uno and an L293D.

#include <AFMotor.h>                  //Go to SKETCH > INCLUDE LIBRARY > then lookup "Adafruit Motor Shield Library"
AF_Stepper motor1RA(24, 1);           //Initializing motor's steps per one full rotation; Connect the motor to M1 port
void setup() 
{
}

void loop()
{
  motor1RA.setSpeed(100);              //Change the value to speed up or slow down the tracker
  motor1RA.step(1, FORWARD, DOUBLE);   //Motor takes 1 step forward; to reverse direction, replace FORWARD with BACKWARD
}
 

With proper polar alignment, a simple clock drive is capable of imaging deep-sky objects, such as the Flame and Horsehead Nebula. This image was captured with a telescope at 565 mm focal length.

Flame & Horsehead Nebula imaged with a telescope mount with a simple clock drive mechanism

Related links:
OnStep Go-To Telescope Controller
View all home-brewed DIY astronomy equipment

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© Anthony Urbano | Manila, Philippines

Modified Celestron Travel Scope 70

The Celestron Travel Scope 70 has a front lens diameter of 70 mm and a focal length of 400 mm. A telescope with these specifications works well for terrestrials observations, both for daytime and nighttime. Due to its size, however, it has a very limited use for astronomical observation. Note that the telescope showed signs of chromatic aberration, like any other low cost telescopes.

Celestron Travel Scope 70 with modified focuser, upgraded tripod and accessories

Related link: View all home-brewed DIY astronomy equipment

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© Anthony Urbano | Manila, Philippines

DIY Universal Camera Adapter

A universal camera adapter allows any camera to be attached to a telescope or binoculars. This imaging method is called afocal imaging, in which a camera with its lens is mounted next to another image-forming optical system such as a telescope or a pair of binoculars. This adapter was built in 2008 and still in use today.

A universal camera adapter for connecting any camera with any telescope

Related link: View all home-brewed DIY astronomy equipment

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© Anthony Urbano | Manila, Philippines

DSLR to Telescope Adapter

A T-ring is a metal adapter with one end that fits on a lens mount and with the other end that connects to a T-adapter. Each camera brand has it’s own T-ring design. The T-adapter connects any T-ring to a telescope.

The Canon EOS T-ring shown in this setup is produced by Celestron, while the T-adapter was fabricated in a machine shop. Some telescopes have threaded focusers that may accept a T-ring directly, thus, eliminating the need for a T-adapter.

Related link: View all home-brewed DIY astronomy equipment

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© Anthony Urbano | Manila, Philippines

DIY Field Battery

Over the years, I have used various types of batteries, but the one I use most often is the deep-discharge lead-acid type. They are robust, low-cost, can be charged with almost any compatible power supply, and most importantly, can double as a vehicle jump-start kit when not being used in the field. I use four 12V 9Ah deep-discharge lead acid batteries connected in parallel, to power the laptop, and another 12V 9Ah battery for the telescope’s tracker. These batteries remain usable for 2 to 3 years.

A modular field-battery to power my equipment during remote imaging sessions

A moderately-sized field battery has more than enough power to last an overnight imaging session.

Related link: View all home-brewed DIY astronomy equipment

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© Anthony Urbano | Manila, Philippines

DIY Pier Extension for EQ Mount

I have built a DIY pier extension to allow my DIY go-to telescope to move without hitting the tripod legs. It consists of three 12-inch L-bars (which I later shortened to 7.5 inches, after measuring the minimum clearance required) that lift the tripod head. I repurposed a tripod head from an old and unused tripod to serve as the base where the L-bars and the tripod legs connect to. The pier extension allows unattended imaging without the risk of damage to the mount or telescope.

DIY Pier Extension

To watch a video of the telescope performing a successful meridian flip without hitting the tripod legs, click here.

Related link: Converting the Vixen Great Polaris mount into a Go-to mount

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© Anthony Urbano | Manila, Philippines

Omega Nebula M17

Omega Nebula M17 captured with a Vixen R114 reflector, an ASI 533MC cooled astronomy camera, dual band H-alpha and O-III filter, with an ASI 174MM guide camera on a 60 mm guide scope. This is one of the brightest deep-sky objects in the Milky Way region, in the part of the sky where you can also find the Eagle Nebula. M17 is visible even with binoculars or small telescopes. You may use the bright stars of Sagittarius to find this target.

Omega Nebula M17, 40 min exposure

For a complete list of astrophoto images, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

Eagle Nebula M16

Eagle Nebula M16 captured with a Vixen R114 reflector, an ASI 533MC cooled astronomy camera, dual band H-alpha and O-III filter, with an ASI 174MM guide camera on a 60 mm guide scope. This is one of the bright deep-sky objects in the Milky Way region, in the part of the sky where you can also find the Trifid Nebula and Lagoon Nebula. You may use the bright stars of Sagittarius as pointers to find this target.

Eagle Nebula, 2 hours exposure

For a complete list of astrophoto images, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

Trifid Nebula M20

Trifid Nebula M20 captured with a Vixen R114 reflector, an ASI 533MC cooled astronomy camera, dual band H-alpha and O-III filter, with an ASI 174MM guide camera on a 60 mm f/5 guide scope. The dark dust lanes that divide the nebula into three sections are visible in this photo. This photo was imaged and tracked using a DIY go-to telescope controller.

Trifid Nebula M20, 1.7 hours exposure

Related links:
OnStep DIY Go-to Telescope Controller
Vixen R114 Reflector on Great Polaris Mount

For a complete list of astrophoto images, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

DIY Telescope Controller | OnStep

I have built a controller for my Vixen Great Polaris mount using the OnStep go-to telescope controller developed by Howard Dutton. I used an Arduino Mega 2560 as the main controller board, a pair of LV8729 stepper motor driver, and an HC-05 bluetooth module (which connects to the OnStep Android app).

I also built a ESP32 Smart Hand Controller (SHC) developed by Charles Lemaire, Howard Dutton, and other contributors, which was derived from TeenAstro . I used an ESP32 module, an OLED display, and a button array for the SHC that connects to the same serial communication lines (Rx and TX pins) used by the HC-05 bluetooth module (I use a toggle switch to select between the HC-05 Bluetooth module for the Android controller and the Smart Hand Controller with ESP32 module) .

OnStep Telescope Controller

I used a pair of 200-step-per-revolution stepper motors paired with 60-teeth and 16-teeth pulley and belt drive system to motorize the Vixen Great Polaris mount with 144:1 worm drive. In this configuration, the total steps are 200 steps * 60/16 reduction * 144/1 teeth worm drive = 108,000 steps per 360 degrees at full stepping. Actual testing showed that accurate tracking is possible at 1/64 microsteps (60 second unguided exposures at 900 mm focal length) . This brings the total steps per revolution to 6, 912, 000 per 360 degrees, or 19,200 per degree (you need to configure this in the OnStep code).

The OnStep telescope controller can be connected to NINA to enable automatic slewing to targets and use plate-solving to validate and refine its pointing accuracy. It also connects with Stellarium to display real-time the telescope’s current position.

Unguided 60 sec exposures at 900 mm with an OnStep-controlled mount, Dumbbell Nebula (1 hour)

OnStep will have very accurate pointing and tracking even with just one-star alignment, if properly polar-aligned.

OnStep Telescope Controller


Related links:
Trifid Nebula imaged with the OnStep DIY Go-to Controller
OnStep Main Page
Smart Hand Controller Main Page
Schematic Diagram OnStep Main Board and Smart Hand Controller

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

M57 Ring Nebula

M57 Ring Nebula imaged with a Vixen R114 reflector at 1800 mm focal length (using a 2X Barlow), OIII and H-alpha dual band filter, and an ASI 533MC astronomy camera. The planetary nebula looks like a small faint circle but relatively easy to find by scanning the region between the two bright stars in Lyra.

M57 Ring Nebula, 1 hour exposure

For a complete list of astrophoto images, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

Omega Centauri

Omega Centauri (NGC 5139) imaged with a Vixen R114 reflector at 900 mm focal length and an ASI 533MC astronomy camera. This target is bright, visible to the unaided eye in relatively dark skies. Use the bright stars of Crux to find this target.

Omega Centauri, 1 hour exposure

For a complete list of astrophoto images, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

M27 Dumbbell Nebula

M27 Dumbbell Nebula captured with a Vixen R114 reflector at 900 mm focal length, OIII and H-alpha dual band filter, and an ASI 533MC astronomy camera. To find M27, use the bright stars of Aquila and Cygnus as pointer stars. This target is bright, easy to find, and should be visible even with small telescopes.

Dumbbell Nebula, 1 hour exposure

For a complete list of astrophoto images, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

M104 Sombrero Galaxy

M104 Sombrero Galaxy captured with a Vixen R114 reflector at 900 mm focal length and an ASI 533MC astronomy camera. M104 is in the constellation Virgo, near the bright stars of Corvus. This galaxy is relatively bright and easy to find.

M104 Sombrero Galaxy, 1 hour exposure

For a complete list of astrophoto images, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

M51 Whirlpool Galaxy

Whirlpool Galaxy M51 captured with a Vixen R114 reflector at 900 mm focal length and an ASI 533MC astronomy camera. This galaxy is found in Ursa Major, in the part of the sky in the vicinity of other galaxies such as M101M81 and M82. This target is relatively bright and may be visible through a small telescope. Use the stars of the Big Dipper to find M51.

M51 Whirlpool Galaxy, 1 hour exposure

For a complete list of astrophoto images, click here.

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

Vixen R114 on Great Polaris Mount

I have recently acquired a Vixen R114 Newtonian reflector (114 mm aperture, 900 mm focal length at f/7.9) on a Great Polaris equatorial mount. The mount does not have motors, but I have converted it into a fully-automated go-to and tracking mount capable of unguided exposures of at least 60 seconds (field-tested without guiding).

Vixen R114 on Great Polaris Mount

The reflector has a very good primary and secondary mirror cells which allowed precise collimation and prevent strained optics. The stock focuser is a 0.965 in barrel which I modified and converted to the 1.25 in standard. The rack-and-pinion focusing mechanism is very precise and sturdy enough to hold an ASI 533 astronomy camera even without using the focuser lock. It comes with a 6 x 30 mm finder which is adequate for pointing at bright targets.

Trifid Nebula M20, 1.7 hours exposure

The Vixen R114 on Great Polaris equatorial mount now serves as my long focal length telescope both for visual observation and imaging.

Related link: Converting the Vixen Great Polaris mount into a Go-to mount

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© Anthony Urbano | Manila, Philippines

Portable Telescope Setup

I have a TravelScope70 which has served as a guide scope for my imaging setup for many years. Now that I have shifted to an off-axis guider (OAG) setup, the TravelScope70 is now being repurposed back to a grab-and-go travel light telescope setup, to be used particularly in astronomy outreach events and visual observations.

Aluminum-lined hard case for the Celestron TravelScope70

The TravelScope70 is a good small-aperture low-magnification telescope, if paired with a good diagonal and set of eyepieces. It will show good views of the moon and allow decent moon photography. Due to the short focal length, small aperture, and lack of a dedicated and more robust mount, the TravelScope70 may be limited to moon viewing and other large and bright targets such as star clusters and nebula.

Related link: Celestron Travel Scope 70

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines