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).
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.
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.
To watch a video of the telescope performing a successful meridian flip without hitting the tripod legs, click here.
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) .
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.
OnStep will have very accurate pointing and tracking even with just one-star alignment, if properly polar-aligned.
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).
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.
The Vixen R114 on Great Polaris equatorial mount now serves as my long focal length telescope both for visual observation and imaging.
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.
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.
Projectors have lenses that may be used to build low-magnification telescopes. I happen to have found an old 70 mm diameter LCD projector lens with focal length of 105-210 mm which I paired up with an eyepiece to build a DIY telescope.
This projector lens, while not designed to be used as a telescope lens, may still provide good views. I measured the proper focus distance and used a DIY adapter to attach a 2-in diagonal mirror and a 40 mm lens to it. This combination produced a 2.6 by 70 to 5.25 by 70 finder scope (wide field of view with ability to zoom). Focusing is done by sliding the eyepiece in and out of the diagonal’s eyepiece holder. I then made an improvised reticle (cross hair) to finally complete the setup. I will be using this DIY projector lens telescope in star-hopping to deep-sky targets and scanning large areas of the sky.
I have built a DIY focal length reducer (focal reducer) by inserting a converging lens from an old telescope along the optical system of a Sky-Watcher Equinox 100ED . The telescope’s native focal length is 900 mm at f/9. With the DIY reducer, the focal length is reduced to 565 mm at f/5.65 (actual focal length as measured by SIRIL’s plate solver function). The lens used was the objective of a Vixen 80 mm f/11 achromat, reducing the native focal length of my telescope by 0.63x.
Focal reducers are optical elements (usually a convex lens or lens group) that converge light from a telescope’s objective. It shortens the focal length and in effect, produces a faster telescope (lower f/ratio) and widens the field of view (larger portion of the sky is seen or captured). Any decent quality converging lens should work as a focal reducer. It works opposite to a Barlow lens which increases the focal length by using a concave lens or diverging lens. Unlike dedicated focal reducers designed to maintain optimal image quality, DIY focal reducers may introduce aberration and must be considered when attempting this modification.
I had to shorten the optical tube by about 200 mm to reach focus, and then reattach the focuser. The focuser’s draw tube was also shortened by 55 mm to prevent it from obstructing the light and stopping down the objective lens when the draw tube moves inward. The telescope’s optical tube has an inner diameter of about 100 mm which has enough space to accommodate the lens cell of the Vixen 80 mm lens. Only the central 60 mm part of the reducer is used due to the presence of a light baffle in the telescope’s optical tube assembly.
I have built a DIY off-axis guider (OAG) using a mirror from a DSLR camera, some tube extenders (2 in and 1.25 in diameter), and a webcam. Best guiding performance currently at 0.33″ (arcsecond) RMS error, at 900 mm focal length, using a mount with DIY controller.
In off-axis guiding, the telescope functions both as an imaging scope and a guide scope. In this configuration, a mirror or a prism receives a portion of the light without blocking the main imaging sensor, sending the light to a guide camera. In this build, I used a high-quality mirror I happen to have found in a non-working Canon 1100D. To build the OAG, I removed the lens from a Barlow so I could get a 1.25 inch barrel for the webcam attachment, and then fastened it perpendicular to a 2 inch extender, where an appropriate side hole has been made. I then fabricated a small mirror mount (like a secondary mirror mount in a Newtonian) using some brass material, to send the reflected light on to the side. The placement of the mirror and the proper spacing to achieve focus required trial-and-error. To use the OAG, focus the main camera first, and then slide the guide camera in or out to achieve focus.
Using a gearbox from an electronic screw driver and a stepper motor from a printer, I’ve built a declination motor drive (direct drive and using gearbox).
The electronic screw driver has a DC motor which I removed and swapped with an old printer’s stepper motor. The gearbox attaches to the declination worm screw using an improvised coupler. I designed it to feature a clutch knob to disengage the motor drive in case I need to slew manually, using the fine adjustment knob.
The stepper motor is driven with an A4988 stepper motor driver board and controlled with an Arduino Uno microcontroller. Two push buttons are used to slew the telescope north or south. I had to perform a field test in order to correctly set the motor’s speed to match the slew speed of the RA motor. The declination motor can be used for declination guiding. I have also tested it to work with a DIY go-to controller.
Equatorial telescopes near the equator have polar axis with very low elevation and as a result, the counterweights may hit one of the tripod legs. With this new set of DIY counterweights, I was able to reposition the weights just enough distance to clear the north-side tripod leg, while at the same time, shift the weights closer to the polar axis, making the whole system more stable.
When imaging targets using a DSLR lens, achieving proper focus may be difficult even when using a Bahtinov mask. Focus adjustments involving very small and precise steps can be achieved using a microfocusing mechanism. In this DIY project, I have modified a Canon 50 mm f/1.8 lens and tapped onto its built in electronic microfocuser.
The focuser is ASCOM compliant and works with astronomy software such as the Nighttime Imaging N Astronomy (NINA) for automated focusing during unattended imaging. It runs on the firmware developed by R. Brown (2021). The modification should work with any lens with built in electronic focusers. To watch a demo video about this microfocuser project, click here.
I have fabricated a customized equatorial wedge for a colleague. An equatorial wedge is simply a platform that is tilted to precisely match the latitude of a place. When used with a wedge, an altitude-azimuth telescope mount may be used in equatorial configuration.
I have been using a Baader Neutral Density (ND) 5.0 Solar Safety Film filter for several years now in solar photography and visual observation. According to the specifications, it reduces solar intensity by a factor of 100,000.
The filter looks like a thin reflective plastic sheet, about A4 size (20 cm by 29 cm). When used with binoculars or telescope, it must be cut to the right size to cover the whole aperture of the optical instrument and installed securely on a rigid frame. Alternatively, the filter may be used without a telescope. Based on my experience, while the solar film may look very delicate and fragile, it is very durable and does not easily get damaged. Special attention, however, must be given to ensure that the film does not get stretched or folded to retain its properties.
The Baader ND 5.0 solar filter produces sharp images with good contrast without changing the white balance. The filter I purchased in 2011 which has been used extensively in almost every solar event visible in my locality is still in excellent condition.
To view posts on DIY projects and astronomical equipment, click here.
The 2-inch Celestron OIII (oxygen III) band-pass filter that allows the 496 nm and 501 nm lines emitted by planetary and emission nebula. The filter looks like a polished mirror that allows some green light that corresponds to the light emitted by emission and planetary nebula to pass through but blocks everything else including most light pollution.
I used this filter extensively in visual observation by ‘blinking’ it in and out between the eye and the eyepiece, a technique used in observing O-III planetary nebula. The use of the filter results in enhanced contrast between the sky and the nebula.
I’ve built an electronic automatic focuser (EAF) for my Sky-Watcher Equinox 100ED refractor for automated and precise focusing. The focuser was built with a stepper motor from an old printer, a gearbox from an electronic screwdriver, A4988 stepper motor driver, and an Arduino Uno. It runs on the firmware developed by R. Brown (2021).
The focuser is ASCOM compliant and works with astronomy software such as the Nighttime Imaging N Astronomy (NINA) for automated focusing during unattended imaging. When the autofocus command is called, NINA takes a series of photos (with a Canon 50D DSLR) at various focus distances and measures the diameter of stars for star fields or the highest contrast for moon and planets. It then calculates the proper distance travel for best focus, and then moves the focuser to focus. An automatic focuser ensures that stars remain focused during unattended imaging runs while you are away from the telescope.
This DIY electronic focuser attached to a standard Crayford focuser features 50,000 focus positions, with buttons for manual focus adjustment and calibration. The controller keeps track of the draw tube’s current position and saves this information even when the focuser is powered off.
I have tested the focuser on several imaging runs now and it appears to be working fine, especially with planets in which I image at 3600 mm focal length.
I’ve built a simple DIY intervalometer for deep-sky imaging, to enable my DSLR camera to take a series of photos of galaxies and nebula. It features a rotary dial with preset exposure times. When used with an autoguider setup, the intervalometer allows taking unattended exposures, while the telescope tracks a galaxy or nebula.
I’ve built a remote shutter switch for my Canon 50D to enable it to take exposures longer than 30 seconds, which is essential in astrophotography. Since the camera already has a battery grip, I just bypassed the battery grip’s shutter button and put an external switch. To make it removable, I used a wire that plugs into a socket hidden neatly in the battery compartment.
I’ve built a DIY battery adapter for a Canon 1100D using a 12V power connector, a power supply regulator, and housing of an old battery. The DIY adapter provides power to the DSLR from a DIY field battery for extended use during imaging sessions.
I have performed filter modifications on a number of DSLR cameras (Canon 450D, 700D, 1200D, 500D, 1000D, 1100D, Nikon D3100, and Fuji X-A1) for me and my colleagues. It involves the removal of the stock UV-IR filter, making the camera more sensitive to H-alpha wavelengths. This modification is helpful only when shooting targets with H-alpha emissions, as most DSLR camera’s standard (stock) filter blocks this part of the spectrum.
Take note of the shift in white balance (reddish hue), which is to be expected in this type of modification. Focus will be affected, your camera may no longer focus with compatible lenses unless you add a filter between the lens and the sensor, to address the shift in focus and to filter out UV-IR. If used with telescopes, you need a DSLR-to-telescope adapter and achieve focus using the telescope’s focuser.
Here are sample images taken with the cameras I have modified (posted with permission).
If you are interested in this kind of camera modification (Philippines only), send an email to email@example.com.