Astronomical Binoculars.

Hi All...

I seem to have generated some interest with my larger than normal pair of binoculars.

To give a little bit of history for those who may not have seen the thread containing the description; I was given the parts for the binoculars as the original owner had no means of providing a mount suitable stand for the telescope; it was mounted on a simple steel post which although providing a means of adjustment, made viewing any heavenly body near the horizon practically impossible unless you had been trained in yoga.

The telescope is quite heavy....you can't lift it manually like a normal pair of binocs, it is about 48" long and some 28" wide, and so the original owner could not use it.

For those not familiar with these sorts of telescope, being a Newtonian Reflector you have to look down the scope to look up at the sky, which is ok when looking directly down the scope as it is some 4ft off the ground .... but when the heavenly body is horizontally positioned you have to get down to take advantage of it.. ... and so I made a new stand have a look at the pics...

Right....any questions... rgds...Bob...

Below.....Scope on original stand..

Below... Scope on old stand, you can see it is difficult to get to eyepieces when heavenly body is near horizontal position.

Scope on new stand I designed using automobile gearbox lifter.

Eyepiece arrangement which can be completely remove from the tubes for cleaning etc.

Hope it provides some interest....

Bob

I am sure it has already been discussed in a thread but what are the advantages of such binoculars over a simple astronomical scope?

I can understand have two parallel scopes, one for an eye and the other for a camera.

JA

Nice workshop Bob

Hi JA.....thanks fizzy.

There are a number of benefits from having a binocular telescope as opposed to a single reflector, the main one being that we are naturally accustomed to using both eyes and it makes observation easier than having to close one eye... in effect I would say it is more comfortable, just try using one eye to read this ... it's not as good is it..?

I find I can see more detail, whether this is because it is more comfortable is debatable or whether it is because of a stereoscopic effect I don't know, there also seems to be an increase in light gathering and the consensus of opinion seems to be that this 2x6inch binocular scope has a similar aperture to an 8inch single reflector.

Other binocular fans have stated that there is an increase in field of view, I don't know how true this is but I must say that those who have a scope of this type are certainly impressed with them.

There are binoscope eyepieces that split the image of a single scope so that there is a way to use both eyes, however I understand that there is a significant loss of light using one of these devices and they ain't cheap!

All in all I would say that for planetary observation and especially lunar observation the binoculars do have an advantage, it seems as if you are actually hovering over the surface ... but whether all the work in manufacturing the thing is worth it is justified.... probably not.... in my case I was given the parts to put together, I would certainly not have entertained making all the optics as well.

There is a problem in that pointing the thing without any instrumentation does pose a problem, and when the desired object is found I find that a slow motion drive is a help, however this must be on a slipping clutch so that the body of the thing can be grabbed at will and manually positioned; I made a simple clutch using magnets.. on the Altitude bearing ....see pic below

Interpupil distance adjuster.

Right hand collimation adjuster... adjustment can be made whilst observing.

Below.. mirror cells showing collimation adjuster gearing.. also shows how the auto gearbox lifter rams are used for Azimuth bearings...very smooth as well.

Very nice Bob. I've been involved with an alt/az goto mount for just such an instrument.

Thanks John....

Just in case anyone is thinking of using one of these auto gearbox lifters for mounting a scope.... the rams are not really steady enough for a good telescope and have to be modified; sleeves need to be fitted down the ram/housing interface and these are quite thin... about 1mm thick and wrapped around the ram with a gap of about 3/4inch along the length.... I made mine about 6 inches long out of nylon/delrin.

The bottom ram housing is of course filled with hydraulic fluid and you need to wear gloves for this stuff...

The ram bushings are easy enough to remove but the large nut on the bottom housing requires a large spanner ... I made one... see pic..

...Bob..

Below......Large nut

Below.. Large home made spanner..

Below... A look down one of the tubes.

Bob

Thanks for the reply.

Years ago I hankered after building a small reflecting telescope but never had the time.

JA

Excellent Bob, as someone who finds two eyepieces awkward and one awful I can see the advantages from a comfort of viewing standpoint. As a glasses wearer it's also amazing how two eyes give more detail than one when looking at something that isn't quite a perfect view.

Neil

Will I need a pair of these if my eyesight gets really bad?

Mike

JA, most astronomical societies run mirror making classes. I have seen a 6" F7 mirror made and silvered, by a complete beginner, in a weekend at such sessions. (though most do take longer at home).
Have a go, nothing like first light with your own mirror.

John

I would love to but I have to be realistic. I am now 70 and feel I should finish some projects before I am removed from the workshop.

JA

Thanks Neil...

Michael.... I suppose a portable head mounted version of the scope would be possible... you would have to make sure you didn't whack the missus on the head with it and a strong neck would be advisable.

John... Mirrors can certainly be made, but they need to have very similar focal lengths or you would have 2 images with different magnifications...and probably a headache to go with it...! The FL's have to be longer than the normal for a Newtonian as the optical path is longer...the FL for the binocs is 43inches.

JA.. I too suffer from a similar problem... I take my time is deciding what project to take on and have a good think about it before committing myself to something far too difficult ... its a bit like deciding to get married..

All..... I have microscope eyepieces as they are purchased in pairs which are x5, x10 & x20 ... although I haven't determined what the FL's of these are perhaps someone might know... the x20's seem to give a magnification of around 100.

Due to the differing eyepiece body diameters I have had to make sleeves for them to fit the holders, I have made the main holders out of plumbing fittings, however the very fine thread needed to fit the holders I made on my Arduino controlled screwcutting lathe.

The plumbing fittings already have an internal thread which has a tpi suitable for focusing, however, the thread is a bit sloppy and I made some friction compound using around 6 parts Vaseline to one part plumbers jointing compound... it doesn't seem to have dried out over a 4 month period...so far.

There is a problem when trying to find objects in the sky, and some sort of angle gauge is helpful here, I use the Stellarium program to find the Az and Alt coordinates and with the lowest mag eyepiece in one holder and a higher mag eyepiece in the other it makes it a little easier to get an overall view of the area before homing in on the object and replacing the x5 with the paired eyepiece for binocular vision.

By the way... if you are interested, some members of the Bolton Group of Astronomers have made really nice looking versions, albeit open frame aluminium on small stands, try Googling it.

nb...have booked my tickets to the London Model Engineering Exhibition...anyone else going..?

I have posted 2 pics as below.... rgds....Bob.

Various eyepieces and sleeves and threads to go with them.

Below

No...! I haven't got one eyeball 1 inch bigger than the other..! this is to show that you can use the x5 for finding and then whilst it is fixed on the object move it out of the holder and go over to the x10 or x20 eyepiece.