Binoculars versus telescopes

[colbe]

Hello,

I would like to ask the question,  are binoculars better than a telescope for deep space objects?

I have a 102mm refractor which is good for planets and I recently bought a Skyliner 200p dobsonian which I was hoping to see a major improvement on galaxies etc.  There is a slight improvement,  but nothing spectacular.  I also have a pair of 10 x 50 binoculars which although you cannot hold still and increase magnification for planets,  for deep sky objects like galaxies they are better.  m31 is clearer and m33 can just be seen,  so when you look through the telescope at m33 with a low powered eyepiece I was expecting to be able to see it easier, but it was impossible to see even when using averted vision.

So would it be better to buy a good refractor on a good mount to track planets and globular clusters at high magnification and just use binoculars to hunt down galaxies?

Thanks in advance for any replies.

[ronin]

It is not a case of "verses". They do different things and are not in competition with each other.

If you want to scan the skies quickly and easily get binoculars, if you want to look at something in more detail then a scope.

As you have a 102mm refractor and 10x50 binoculars it appears a bit odd asking if you should buy a scope or binoculars, you already have one of each and so know the capabilities of either.

What is it you want your next instrument for?

[Alien 13]

Hi colby and welcome to SGL i asked a related question recently regarding the percieved brightness observed with differing scopes/binos and the answers somewhat supprised me it changed my view of scopes being light buckets.http://stargazerslounge.com/topic/219863-pupil-size/

Alan

[colbe]

Hello,  

Thanks for the replies,  what I am trying to get at,  in reply to "ronin" If I new exactly what to expect from different scopes and binoculars before I bought them,  I would probably of not bought the dobsonian as the views are no better and probably worse on some deep sky objects than the binoculars.  I was just wanting other peoples thoughts.

Thanks

[ollypenrice]

I think you've picked two rather exceptional targets in M31 and M33 and, on these targets, I can see where you're coming from. I was observng them both in my 8x42s from our dark site last week. M31 is a great bino target because the galaxy is so wide that seeing it framed by dark space is thrilling. M33's low suface brightness means that it has a more concentrated appearance at low power. Even in a large scope it tends not to show many features.

However, on other targets a telescope can bring small details to life in a way that binoculars can't. You should get to the dust lanes in Bode's galaxy, for instance. You should see a clear disk and the dumbbell shape in M27. The Ring will be just that, a ring. The Trapezium in M42 will show four stars and distinct structure in the nebula. Globular clusters will no longer look like fuzzy stars but will resolve into multiple points of light.

You'll see a Swan shape in the Swan and a patch of nebulosity in the Trifid, possibly resolving into the tripartite structure implied by the name. And so on and on.

During the bino session I mention I did wonder, myself, whether on M33 and M31 you didn't have at least as much fun as with a telescope. But not all targets are like that.

Olly

[itmo]

I think binos and telescopes complement eachother. Also the best for deep sky is ofcourse binocular telescope.  

[acey]

1. Binoculars can beat telescopes on very large, low surface brightness targets viewed at dark sites.

2. Telescopes beat binoculars on most of the targets that amateurs usually look at.

3. A dark sky is always better than a light-polluted one.

This is demonstrated by the diagram below which shows visibility curves for 3 instruments under different conditions: 10x50 binoculars at a dark site (SQ 21.5), a 6-inch refractor at the same dark site, and a 16-inch reflector at a light-polluted site (SQ 20). The diagram plots target surface brightness versus size. For each instrument curve, anything on or below the curve is predicted to be visible, anything above is invisible. Data points are galaxies in the Virgo Cluster.

Curve A is the binoculars, B is the 6-inch (with exit pupil 3mm), C is the 16-inch (with same exit pupil). With the 16-inch at the light-polluted site only one galaxy is predicted to be (just) visible. The 6-inch at the dark site is predicted to show all of them. The binoculars at the dark site are predicted to show less than half, but note that a target of very large size and very low surface brightness (i.e. lying in the top right of the diagram) might be visible with the binoculars but invisible with the telescope.

Obviously the results will vary depending on the observer: the effect for any given observer is to move all the curves up or down by an equal amount. A particular person might be able to see all the Virgo galaxies with the 16-inch at the light polluted site, and in that case will see even more with the other instruments at the dark one. This does not alter the qualitative results stated above as points 1 to 3.

The diagram comes from this paper which gives full details of how the calculations are done (and explains various caveats which should be taken into account): http://arxiv.org/abs/1405.4209