A DIY Amplifying Eyepiece for Astrophotography

On the subject of viewing nebulae, galaxies, and different deep-sky objects, newbie astronomers on a funds have had two choices. They will view with the bare eye by means of a telescope and understand these spectacular objects as faint smudges that don’t even start to seize their majesty, or they will seize long-exposure photos with astrocameras and show the outcomes on a view display screen or pc, which robs the immediacy of the stargazing expertise.

Stand-alone telescope eyepieces with energetic mild amplification do exist for a real-time viewing, however business merchandise are dear, costing lots of to hundreds of {dollars}. I wished one thing I might use for the public-astronomy remark nights that I manage in my group. So I made a decision to construct a low-cost DIY amplifying eyepiece, to make it simpler for guests to look at deep-sky objects however with out requiring a big monetary funding on my half.

I shortly realized there was already an business replete with {hardware} for dealing with low-light situations—the security-camera business. Confronted with the problem of monitoring areas with a wide range of lighting, typically utilizing cameras unfold out over a big facility, makers of closed-circuit tv (CCTV) cameras created a video normal that makes use of digital sensors to seize photos however then transmits them as HD-resolution analog indicators over coaxial cables. Through the use of this Analog Excessive Definition (AHD) transmission normal, you possibly can connect new cameras to preexisting lengthy cable runs and nonetheless get a high-quality picture.

A CMOS-image sensor module from a safety digicam [top left], a USB seize card [bottom left], and an OLED viewfinder [right] course of analog video information.James Provost

Whereas I didn’t want the long-distance functionality of those cameras, I used to be very interested by their low worth and talent to deal with dim situations. The enterprise finish of those cameras is a module that integrates a CMOS picture sensor with supporting electronics. After some analysis, I settled on a module that mixed a 2-megapixel Sony IMX307 sensor with a supporting NVP2441 chipset.

The important thing issue was selecting a sensor-chipset mixture that helps one thing referred to as Starlight or Sens-Up mode. This makes the digicam extra delicate to mild than the human eye, albeit at the price of slightly velocity. Photographs are created by integrating roughly 1.2 seconds of publicity time on the sensor. That may make for uneven safety footage, but it surely’s not noticeable when making observations of nebulae and different astronomical objects (except after all one thing actually bizarre occurs within the sky!)

From Astronomy To Safety Cameras and Again Once more

The existence of the Sens-up mode is definitely a part of the technical heritage of digital imaging sensors. CMOS sensors have been developed as a successor to charge-coupled units (CCDs), which have been eagerly embraced by the astronomical group following their introduction in 1970, changing long-exposure photographic plates. Nonetheless, the power to take publicity frames so long as one second isn’t one thing that CCTV cameras are designed for: It may be extra of a downside than a characteristic, resulting in blurred photos of transferring objects or individuals.

Consequently, this functionality isn’t talked about within the product descriptions, and so discovering the proper module was probably the most difficult half: I had to purchase three totally different digicam modules earlier than lastly touchdown on one which labored.

The output from the digicam module is handed to a digital viewfinder, which shows each the video and management menus generated by the module. These menus are navigated utilizing a four-way, press-to-select joystick that connects to a devoted header on the module.

The output of the digicam can also be handed to a seize card that converts the analog sign to digital and supplies a USB-C interface, which permits photos to be seen and saved utilizing a smartphone. All of the electronics may be powered through battery for full stand-alone operation or from a USB cable connected to the seize card.

The analog HD module may be managed instantly utilizing a joystick to navigate onscreen menus. Energy may be offered externally through USB-C connector on the seize card or through an non-obligatory battery pack.James Provost

The elements slot in an enclosure I constituted of 3D-printed components, designed to match the 32-millimeter diameter of most telescope eyepieces for straightforward mounting. The entire thing price lower than US $250.

Testing out the Amplifying Eyepiece

I took my new amplifying eyepiece out with my Celestron C11 telescope to present it a attempt. Quickly I had in my viewfinder the Dumbbell Nebula, also referred to as Messier 27/M27, which is generally fairly arduous to see. It was considerably brighter in comparison with a naked-eye remark. Definitely the distinction wasn’t as marked as with a business rig that has noise-reducing cooling for the sensor electronics. However it was nonetheless an infinite enchancment and for a fraction of the price.

The Orion Nebula, some 1,340 mild years away.Jordan Blanchard

The amplifier can also be extra versatile: You possibly can take away it from the telescope, and with a 2.8-mm HD lens fitted to the camera-module sensor, you need to use it as a night-vision digicam. That’s useful when making an attempt to function in darkish out of doors situations on starry nights!

For the longer term, I’d prefer to improve the USB-C seize module to 1 that may deal with the sensor’s digital output instantly, reasonably than simply the analog sign. This is able to give a noticeable increase in decision when recording or streaming to a telephone or pc. Past that, I’m interested by discovering one other low-cost digicam module with an extended publicity, and refining the 3D-printed housing so it’s simpler to construct and adapt to different observing setups. That manner the eyepiece will keep inexpensive, however individuals can nonetheless push it towards extra critical electronically assisted astronomy.