DIY Artificial Star

[moriniboy]

Had a go at making myself an artificial star so I can collimate my scope whilst the weather was being so unkind.

£3 super bright LED torch from maplins (single LED version) and a spare unused mini camera mount.

The cover is tin foil with black insulation tape both sides (apart from the pinhole area) and a pinhole using the finest needle I could find (the smaller the better)

Also drilled a 5mm hole through the original plastic torch front so the light goes direct to the pinhole. The remainder of the plastic surround supports the tinfoil.

Due to internal reflections I decided to blacken out the torch silvering right up to the LED and the rear face of the plastic torch front.

In use it seems to work well, the light is visible from 40+ metres with the naked eye and the camera mount can be adjusted so the LED is directly in line with the pinhole and scope.

Ok so its not the prettiest of solutions but it works for me

Hama mount and torch zip tied on

Internals blackened out to reduce reflections

In use

[Trull]

I did much the same - and then upgraded with a length of fibre networking cable so that I got a far narrower beam. If you ask your local IT bod they will probably have a short length spare... or even buying is about a fiver.

[alexog]

I've made something very similar. Good tip on using a mini tripod to mount it on. I got one from Poundland, useless for photography but I'll root it out.

I've been thinking about mounting a small negative lens in the front. I'm hoping it will reduce the size of the pin point. Also if the lens distance to the hole is the same as it's focal length (set at infinity) then there'd be no need to close focus on it. I don't have much space and I'm not sure how close the focus is on my 'scope with or without extension tubes. Perhaps a mirror to extend the distance also, then the "star" would be next to the 'scope for easier adjustment. With the "star" being pretty much on axis with the 'scope then ghost images from an ordinary mirrors shouldn't be much of an issue. I've got an optical flat and a mirror from an old diagonal but they're pretty small and getting everything lined up would be tricky...

There used to be these things in the sky to test optics with, I forget what they were called