Thinking of buying some Binoculars but not sure what ones to get either a 7 x 40 or 8 x 50
what could I expect to see with either of those eg....... moons of Jupiter, nebs , gals etc...????????????????//
7x50's are the classic astro binoculars. They have a 7mm exit pupil which is ideal for a fully dark adapted young eye. Unfortunately, as you get older your eye dilates less and eventually won't fit a 7mm diameter beam of light through.
8x50s and 10x50s will collect the same amount of light, and have a smaller exit pupil diameter, but the trade off for more magnification is less field of view and they get harder to hold steady. Above 10x I'd recommend you mount them on a tripod or rest of some sort.
50mm objective binoculars will theoretically gather 51x more light than the naked eye (assuming a 7mm pupil in your eye). A 40mm objective will capture 32x as much light, so you'll see 4 magnitudes dimmer than naked eye. 50mm will allow you to see 4.8 magnitude deeper.
You can certainly see the moon of Jupiter, and you'll see nebulae and galaxies though they will in most cases be little fuzzy patches. You will get the best views of the Pleaides with binoculars, and similar large objects in the sky that are too big for most scopes.
large open clusters are often the best small bino objects, and the large nebulae like eta, or magellanic clouds.
If you live in light polluted area, i think the 7mm exit pupil will be a bit much, they are more for dark skies where your eyes can fully dark adapt & take in the whole 7mm (measure your pupils in bathroom). I think 10x50 are the best for light polluted areas. (for tech explain see gary seronik website)
As for the diff between 7x50, 8x50 & 10x50 there is not a big difference - at this level it will be more about the quality of the glass, & coatings. I recommend you buy a good brand & they will keep for many years.
I reckon a 10x50 (10x42 and 10x60 are other available options) pair of astronomical binoculars ($70-200) with a fairly stable camera tripod (around $100-120) and the appropriate tripod adapter ($10-20) will get you started.
Don't be talked into a set of zoom binoculars and don't buy a pair with a red coating on the objective.
Even with a pair of 7x50 binoculars you can observe many globular clusters if you can find some darker skies. You won't be able to resolve the stars but they are a wonderful sight.
Here are a few to target ...
The wonderful omega Centauri and 47 Tucanae.
M22 and M55 in Sagittarius.
NGC 6397 in Ara.
NGC 6541 in Corona Australis.
NGC 6752 in Pavo.
M13 in Hercules.
M10 and M12 in Ophiuchus.
If you are purchasing binoculars, a simple test for collimation is to check you can merge the left and right fields into one circle of view. You should not be seeing double images of the same objects.
if your after 10x50 binos i have one for sale in the telescope section for $100 byitself or $150 with the tripod connector, there bushnells i payed 240 for them last year
Yeah im thinking of finally getting some binos too 
