"Astronomy" binoculars

[ScottM]

This might be a silly question, but as I know almost nothing about binoculars, telescopes, etc., is there any real difference between "astronomy" binoculars and other types? If so, what makes them effective for astronomy in particular?

[Charic]

A very large aperture makes for useful `astronomy` binoculars as they can gather more light allowing you to see fainter objects. The side effect is that as the Objective lenses get bigger, so does the price and the weight. Anything over 10x magnification my be difficult to hand-hold so may need  a support system, tripod/mono-pod ect to aid with  their stability, otherwise the image dances all over the place. 

The numbers on Binoculars indicate magnification and aperture  so 7x50 means 7x magnification as against the naked eye, and 50mm aperture. Also if you divide the aperture by the  magnification the result is the diameter of the "exit pupil". That's the image that appears to be projected from the eyepieces if you hold the binoculars up to bright light at arms length. This image diameter of 7.1mm will match the dilated pupil of a younger person, to maximise the light into the eye. As we get older the eyes ability to dilate reduces.

Also its possible to multiply the two numbers to give a  visibility rating so 7x50 becomes 350 as a night sky performance, if comparing like for like!

EDIT  check Adler v.  Bishop regarding  performance

[baggywrinkle]

Have a look at http://binocularsky.com/ lots of useful info...he writes good books too.

[Russko13]

Most binoculars if not all to a certain degree can be used for astronomy, most people including myself tend to use 10x50. magnification being 10x and aperture ( size of objective lens) being 50mm, most binoculars designed for astronomy will have blackened prisms inside the tubes to allow for more light gathering

[ScottM]

Thanks everyone. I went for the $50 binoculars kit from Orion to start. Those bins are 10x50, so based on what you all have said it seemed it was worth the try. I'll keep all of this in mind for when I decide to upgrade, too.

[michael.h.f.wilkinson]

Enjoy the new bins. The 10x50s are a really good workhorse.

One other thing which sets some binoculars apart for astronomical use is the presence of individual helical focusers rather than the centre focusing wheel with diopter control on one EP. The individual focusers are really handy as they do not slip, and you only want to focus on infinity. The standard central system can be fine, as long as the "bridge" connecting the EPs does not wobble too much, and has distinct advantages during daytime observations. Regular 10x50 bins are great all-round astronomy and birding bins

[baggywrinkle]

10x50's good choice, easy to hold in the hands without getting too tired.

A good reclining camp chair is also a good idea. You can sit in comfort to sweep and observe.