collimator

Dear all,

I have always had an interest in optics ,rekindled by my friend and boiler making mentor a few years ago when he gave me several books on telescope making and a 10" mirror he ha just ground[!]. Recently I have been looking at some old binoculars and decided that they needed re collimated. This set off the usual quest for more information- is this a prerequisite for a project or just procrastination?. Having read several articles, one on the internet[google sun images method for collimation of binoculars] really interesting. I tried a 10 minute lash up rig and the principle seems to work .However the watery yorkshire sun and the freezing wind suggested a search for a more standardised source of parallel light ,preferably warm and indoors. thoughts of light sources and lenses swiftly moved to musings on laser pointers as a light source. then it struck me I might be reinventing the wheel and someone one the list has probably already built a binocular collimator and found all the problems , fixed them and is on to his mK 6 b already.

Hence the question -anyone made one or got ideas

Regards Ian

All this because given ww2 kershaw 6x30's in need of TLC

Sodium street lamp as light source? (one provide by the council not getting your own inside)

I read a book on telescope lens grinding as a teenager and often thought of making one but not really interested in astronomy, just interested in the technique. Did you see what I think was an antique lens grinding stage on one of the stands at the Ally Pally show? They were asking what it was.

"Checking alignment of binoculars is usually performed by professionals with the help of a 'collimator' "

Er, no, it's usually performed by holding them backwards at arm's length and looking at the horizon. If the horizon in each lens doesn't line up they're misaligned and you chuck them and get a new pair!

Maybe it depends on what type of professionals right enough

Interesting article though.

Scott (30 years at sea)

What's wrong with using a laser pointer?

Neil

You will need two collimators to adjust a pair of Binos. The two collimators themselves need to be collimated parallel and have the same focus. One body will have a reticule that is a vertical and horizontal slit. The other will be a simple black cross that will be smaller in width than the slits in the other one.

The is a need of a solid mount for the Binos and the ability to pivot the bodies seperately.

The Binos mounted on the clamp and each body focussed on the individual reticules. (The principle of the collimation is that the rays of light going into and coming out of the collimators is parallel. This is called Solar Focus)

If the Bino images do not coincide then the Binos are out of collimation and will have an error of Convergence or divergence or supravergence, there will be a combination of these faults and adjustments are by eccentric rings around the OG's or adjusting screws that move the prisms.

Swinging the Bino body around the pivot will tell which body to adjust as the images will move as you do it. This is not a job for a Tyro or a learner and it needs experience and knowledge.

Bear in mind that a lot of Binos have glued components and are non adjustable, that is they are adjusted by the maker and then the seats of the prisms are glued forever. The lenses the same.

There are several different methods of Bino collimation and field adjustments are not really possible unless with what is called a 'Bar Collimator', but it is not as accurate as a double tube bino collimator.

Another is a large lens that is bigger in diameter than the width of the binos. This is then used as a field lens and is quite accurate.

The effect of the errors in Binos causes headaches and eye strain when used for a period of time. Much better to use only one body if they are faulty.

Clive

Regards using a Laser pointer, the Laser will go through an optical system in any position in the diameter of the objective and as such is not a lot of use. You still have to view the optical system to adjust and I do not reccomend any exposure to any laser light. Lasers themselves need collimating, the laser tube being physically shifted about in another tube (Body) and  adjusted in both x and y planes and also adjusted by rotation of the body longitudenly. Again not for the Tyro or uninitiated users.

Edited By Clive Hartland on 21/03/2013 21:57:55