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Reticule


LeeB
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Converted an old 10mm skywatcher eyepiece to a reticule yesterday, what a difference to tracking accuracy, three star align and a decent polar set up, the mount hit everything with 10% of centre at 160x, all for a couple of hours work and a hair from my daughters head.

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I made hundreds of human hair crosshairs during my career and have a sizeable bald patch to show for it. I taped the hair to the eyepiece, centred them by eye (they don't have to be exact, the cross point is the reference) and then applied some adhesive before removing the tape. You sometimes have to adjust the field stop to bring the hairs into focus. :smiley:

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I made hundreds of human hair crosshairs during my career and have a sizeable bald patch to show for it. I taped the hair to the eyepiece, centred them by eye (they don't have to be exact, the cross point is the reference) and then applied some adhesive before removing the tape. You sometimes have to adjust the field stop to bring the hairs into focus. :smiley:

I did do something similar, but always found it very fiddly. I will give it a shot on my Antares 25mm 70deg EP

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Just wondered what the thickness of human hair was... 40 - 250 microns, apparently. ;)

We used to use a lot of Wire chamber detectors (don't worry overmuch). But those used thin wires, made from various materials, in the range 20 to 150 microns. Handling 20 micron was strictly for the experts! But 30 microns was just possible - 100 Microns, almost a doddle? (It has a useful "stiffness" factor!). I see it's possible to obtain:

http://www.wireandst...tres--2406.html <shrug> A lifetime's supply for a couple of quid?

Wire can often stand a fair few grams tension! Some materials are better than others - Apparently Aluminium tends to slip through adhesive, 'cos of the oxide layer. Maybe use what we did... Get the gold plated stuff? :p

Edited by Macavity
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We made some very good crosshairs from glass. A glass stirring rod was heated in the middle until molten and then the two ends were rapidly pulled apart. This left a very fine glass hair which was uniform in thickness and rigid and straight. With a bit of practise it could be snapped to length. Interestingly, as they were transparent, the edges produced double lines. A star was diffracted when centred on the cross. :smiley:

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Converted an old 10mm skywatcher eyepiece to a reticule yesterday, what a difference to tracking accuracy, three star align and a decent polar set up, the mount hit everything with 10% of centre at 160x, all for a couple of hours work and a hair from my daughters head.

And your daughter doesn't mind standing out in the cold all night?..... what a trooper :D
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I just turned an Antares 25mm 70 deg into a reticule EP, by adding two hairs of mine (little bits of duck-tape did wonders). The Antares 25mm 70 deg allows you to unscrew the barrel, attach the hairs to the top of the barrel, which, when screwed back in place makes them sit snugly against the field stop. The inner diameter of the EP housing is 35.4mm, so I must say I was tempted to buy one of these:

http://www.maxlevy.c...fm?ProdID=AA068

However, I am not sure what the shipping costs are (could get them by logging onto their shop, which caused the browser to throw up an "expired certificate warning" so I left it at that). It still would be the neater solution.

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Awhile back I purchased a used eyepiece which had a crosshair insert. Though I have not seen one before, the seller said it was from "Tal". It threads into 1.25" eyepieces and comes to focus in those of 9mm and lower power. An item worth looking for, here are a couple photos of it.

post-21902-0-49384000-1368688589_thumb.j

post-21902-0-62430000-1368688605_thumb.j

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