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finder scopes

orionhunter

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orionhunter

orionhunter

Posted
Posted

two questions please.

1. what is the correct battery for a (cheap. no name) red dot finder scope require?

(acquired a non working one, with no battery inside)

2. how and where, do i put cross hairs onto a cheap tasco type finder scope?

(making a DIY scope for my grandkids).

can anyone help me?

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Capricorn

Capricorn

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Posted

I am guessing that they use a 2032 battery. Probably the most common one around, about 1/2 inch across (12mm).

After that I have no idea. If no-one else comes up with anything pay a visit to one of the pound shops or similar and buy a pack of multiple batteries and see which one suits.

May be a look at Astro shops web sites may turn up reference to a battery used.

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russ

russ

Posted
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Yep, CR2032 is the most likely battery for a generic RDF. I bought a pack of 6 off Ebay for £1.99 delivered. Tesco's wanted that for one. Having 6 is a full back for that time you forget to turn it off (which happens a lot).

I put two threads of cotton on the bottom of the eyepiece for some crosshairs. It wasn't the best job in all honesty but they did work. All be it they were a touch curvy. But i had the excuse of being 13 at the time and not knowing what i was doing. :eek:

Russ

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phattanglo

phattanglo

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Yes two threads under the eyepiece.

If you're confident to do so, the place to attach the hairs is under the threaded locking ring which holds the lenses in place.

As it's a finder scope there may be four tiny notches on the back of the ring which can be used as a guide for the hairs.

I think the hairs are actually supposed to be extremely thin copper wire or similar.

You could use traditional hair I'm sure, but I used a couple of the bristles from a lens blower brush which had the advantage of being nice and straight and dark with no wispy bits sticking out like cotton would have.

Stick one end of the bristle in one of the notches with a tiny drop of Superglue, once set stick the other end while holding under gentle tension.

Repeat for the other hair and trim the ends with a sharp blade it seems to work quite well.

Hope this has been of help to you.:eek:

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Merlin66

Merlin66

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I use some fine copper wire from a small transformer I found in an old transistor radio years ago...

Make a stiff card ring with an outside diameter to suit the field stop in the eyepiece; mount the wire across the card ( superglue) and then place the card into the eyepiece, push up hard to the field stop and the wires should be pretty close to focus point.

If you need some very fine wire drop me a PM and I'll send you some.

Ken

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glowjet

glowjet

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I have had a go at making these, I found a small metal sleave that fitted inside the ep up to the field stop, put four nicks in the edge with a file, placed it on a board then streched the finest copper wire I could find of an old trasformer, any fine wire will do, put four nails in the board, place the wire in the nicks tightening each strand and wind it round the nails, adjust till you are happy you have a perfect cross then put a blob of Areldite in each nick and leave over night to go hard, trim as necessary when all is set, keep your fingers away from the wires and handle with care, you can now place the sleeve back into the ep and adjust, when you are happy with the view, lock the sleeve in place with two or three drops of glue inside the ep, old Huygens ep`s around 12mm are good to use.

John.

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orionhunter

orionhunter

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1. got some cr2032 batteries from the local pound shop and the red dot scope works fine.

2. after some hilarious attempts at fitting cross hairs, (ive got thumbs like a gorilla) i did it with using tiny bits of blue tack and my own hair!

the grandkids think im a god!

:eek:

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haitch

haitch

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i read somewhere some Astronomer uesed spiderweb for the crosshairs.......kev

I think that might have been me - in case anyone is confused, spiderweb is a fine thread used by fly fishermen to tie their flies.

Does one end or other of the finder not screw in and out to achieve focus?

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phattanglo

phattanglo

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It seems when scopes were first developed for use with a rifle the crosshairs were actual spiders web.

The spider creates the thread from a number of orifices called spinerets or something and incredibly the scopemakers teased out just one of these fibres from the thread to use for the crosshairs.

Hence the work involved meant they were so expensive only the landed gentry could afford them.

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