Solar Finder For Telescope

Are you a fan of solar astronomy? Centre your telescope on the Sun safely via this straightforward add-on.

You watching: Solar finder for telescope


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Warning: never look at the Sun straight or via devices not designed especially for safe solar viewing, as this deserve to reason irreperable damages to your eyes.

Although most astronomers observe the night sky, many likewise rotate their attention to the closest star to Earth – the Sun.

Inexpensive solar film filters carry out an affordable means to adapt tiny telescopes for solar observing and also imaging, revealing sunspots and bideal faculae.


If you invest in a Herschel wedge you will get an even better view, while narrowband hydrogen-alpha and calcium-K filters allow you to watch a greater selection of solar attributes.


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Materials – 150mm size of plastic or aluminium tube, 25-32mm in diameter (ideally a great fit for your existing finder bracket); 2 end caps that fit the tube (a pair of spare eyeitem caps or bottle caps); babsence and white plastic. 

Just as it isn’t safe to see the Sun through a telescope without having actually a certified solar filter fitted, the exact same is true of a much smaller sized finderscope.

Looking at the Sun through a finder will certainly reason instant damage to your vision.

How then, execute you centre the Sun in your field of view?

One way is to line the scope up so its shadow on the ground is as tiny as feasible, yet this isn’t exceptionally exact, particularly if you have actually your scope put up on grass.

The many precise way is to usage a specialized solar finder, a maker that provides the ancient principle employed by pinhole camages.

Instead of making use of a lens, a tiny hole acts as an objective that jobs a little photo of the Sun onto a screen at the much end of a tube.


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In use, the Sun is projected onto the white disc; it’s aligned as soon as it’s on the main dot.Credit: Neil Wyatt
It is attached and changed in the very same means as an plain finder, but rather of looking through a solar finder you watch the display on the finder’s rear and readjust the telescope till the picture of the Sun is in the centre.

The brightness of the Sun indicates that a hole less than 1mm across is sufficient.

The resulting estimate will certainly be around 2mm across, and our display around 150mm from the finder.

Although the photo is slightly enlarged, the light gathering power of the pinhole is puny – so it is completely safe.

See more: Solar Hot Water Sizing A Solar Array, Solar Hot Water

How pro will certainly you go?

Our prototype finder was made by simply taping a item of babsence plastic via a pinhole to one end of a steel tube and also a white plastic display to the other.

This wasn’t exceptionally durable yet verified the principle, enabling us to align a telescope through the Sun in a matter of seconds.

Having accessibility to a mill and a lathe, we then made a deluxe variation making use of a babsence anodised tube from some bicycle forks via neatly knurled end-caps to host the plastic discs in location at each finish of the tube.

You can, optionally, additionally mill a slot in the side of the tube so you have the right to check out the screen from either side.

This finder operated so well we made a decision to dedicate a tiny achromat refractor to solar work-related by swapping out its continuous finder for our solar one and semi-permanently fitting a Baader solar filter to the telescope’s major lens.

With a small, equatorial tripod it’s a great solar grab-and-go kit for those days once the Sun is only peeping out from behind the cloud for a couple of minutes at a time.

The solar finder defined in the Step by Tip does not call for the machine shop – the tools you require are no more sophisticated than a junior hackwitnessed and a craft knife.

The end outcome might not be quite as pretty as the machined variation over, yet it functions equally well as it has the exact same ‘high-tech’ optics.

A lick of spray paint or even an offcut of carbon fibre wrap will quickly make it look great sufficient to match any kind of solar scope.

In usage, you should swap it for the normal finder on your solar-filtered telescope (never before, ever before leave an optical finder on a solar setup).

You may must usage some packing about your home-made finder if it is smaller in diameter than your finder bracket.


Once you have actually your scope aligned through the Sun, just use the usual adjustment screws to centre our star on the display screen, and that’s it.

Whatever before mount you have actually, manually tracking the Sun is currently no more hard than keeping it in the middle of the screen.