This month's project helps you aim your scope at a target in the night sky. It is called a zero-magnification finder because the view is the same size as seen with your naked eye. The finder projects a red circle onto the background sky and you move your telescope to align the centre of this circle with your target. Many stargazers use similar devices because they allow you to keep both eyes open and see a much larger area of sky, making it easier to jump to the target.
Our design has a red LED that illuminates the white interior of the front of the case. The LED is powered by a coin cell battery, via a switch on the back panel. The red light is reflected backwards through a clear glass screen, painted matt black except for a small ring in the centre. The light is then reflected upwards by a mirror mounted at 45° and through a lens, which produces a sharp image. This is reflected backwards again by a glass viewing screen, mounted at 45° in a hood. When the distant sky is viewed through this screen, the red circle is superimposed on it.
We sourced the components for this project imaginatively to keep the cost down. The LED, coin cell holder and switch are from an educational supplier. The clear glass was cut from an old picture frame, and we used the frame's thin MDF backing to make the case. The front surface mirror is a disposable dentist's mirror. We found these online, along with the lens, a Fresnel magnifier sheet.
Mounting matters
Denne historien er fra February 2023-utgaven av BBC Sky at Night Magazine.
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Denne historien er fra February 2023-utgaven av BBC Sky at Night Magazine.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
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Could We Find Aliens by Looking for Their Solar Panels?- Designed to reflect ultraviolet and infrared, the panels have a unique fingerprint
Researchers searching for life beyond Earth spend a lot of time thinking about what telltale signs might be detectable astronomically. Forms of unambiguous evidence for the presence of life on another world are known as biosignatures. By extension, techno signatures are indicators of activity by intelligent, civilisation-building life.
Antimatter- In our continuing series, Govert Schilling looks at antimatter, the strange counterpart to most of the matter filling our Universe
Particles and corresponding antiparticles are very much alike, except they have opposite electrical charges. For instance, the antiparticle of the electron - known as the positron - has the same tiny mass, but while electrons carry a negative electrical charge, positrons are positively charged.
Where Have All The Milky Way's Early Stars Gone?- Our Galaxy has a curious lack of pristine stars
The Big Bang produced a Universe filled almost exclusively with hydrogen and helium; all other elements - what astronomers call metals - were produced by stars, supernovae and everything that happens later. So if you can pick out a pristine star with no metals polluting it from among the billions in the Milky Way, then you are likely to have a star dating from our Galaxy's earliest days.
Inside The Sky At Night - Two years ago, exoplanet scientist Hannah Wakeford received some of the first data from the JWST
Two years ago, exoplanet scientist Hannah Wakeford received some of the first data from the JWST. In July's Sky at Night, we discovered what she's learned since then.
How to stack DSLR data in Siril
Easily combine multiple frames to boost detailin your astro photos
Lunar occultation of Saturn
You'll need to strike a balance on 21 August to capture the Moon covering the ringed planet
How to plot a variable star light curve
A rewarding project to chart stars that change brightness
Smartphone photography with a telescope
Mary Mcintyre explains how to get impressive night-sky images using your phone
Once-a-century solar storm is overdue
If a Carrington Event struck today it would be catastrophic, says Minna Palmroth
The new era of human spaceflight
There's been a step-change in crewed space missions since the dawn of the 21st century. Ben Evans charts its course and looks ahead to future horizons
