Doublers / how they work? (1 Viewer)

Does anyone here know how doublers work for binoculars?

Companies such as Swarovski and Vortex appear to have them but they are only compatible for their brand name binoculars. So do their eyepieces have some sort of socket for that? It all doesn't seem to make sense.

And are doublers 2x monoculars in their own right?

Any information would be appreciated....

This might help a little, these doublers only fit some eyepieces.

http://www.birdforum.net/showthread.php?t=219014

Our UTA (universal tele adaptor) was a 2.5x unit but will soon be replaced by a 2x:

http://www.opticron.co.uk/Pages/uta.htm

As you can see we supply a number of different push-fit rings to allow the unit to be used with a range of different binoculars, monoculars and scopes. If you know the outer diameter of the eyepiece on your optic, you can check if there's a compatible ring.

The optics are simple and have no focus control so whilst you can look through it and see the 2x magnification, only a certain depth of the view is in focus.

A Barlow lens is a common doubler used in astronomy:

https://en.wikipedia.org/wiki/Barlow_lens

HTH

Pete

A Barlow lens is a negative lens between the objective and eyepiece.
The power depends critically on its position, so a 2x could be 3x. In fact some are, with the use of a spacer ring. Could be 5x as in Teleview etc.

Matched doublers for say Vivitar lenses are computed to fit a particular lens and are more elaborate.

Barlows can be 2 element up to 7 element or so. Called telenegative lenses. Some cheapoes are single negative elements. Useless usually.

The Questar has an inbuilt flip barlow.

The Afocal 2x, 2.5x and 3x are different, and fit at the back of the eyepiece.

There are afocal lenses that fit on the front of lenses. Usually to provide wider angles of view.
These have the remarkable property of increasing the lens speed.

I thought refractive lenses had a maximum speed of f/0.57.
But there is a Zeiss f/0.33. I think it must have a built in afocal front lens. It seems to have a huge elliptical front element. Very expensive.
1960s Carl Zeiss Super-Q-Gigantar 40mm f/0.33.
Apparently Q stands for nonsense in german. Made with condenser lenses, looks parabolic. $80,000.

There were also rangefinder cameras with in between lens shutters, that had 3 different front options, typically giving 35mm, 50mm and 85mm focal lengths. These are part afocal really.