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PostPosted: Thu Sep 24, 2015 6:55 pm 
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Joined: Thu Sep 24, 2015 6:43 pm
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Hello,

I really appreciate any help on purchasing my first pair of binoculars for astronomy.
I am intending to go for 10x50 as I live in a fairly light polluted area so think after reading a few posts these might be the best option.

It seems I have a fairly small IPD for the 10x50 binocular specification in general, so I have narrowed :roll: the choice down to these:

Nikon Action EX 10x50 CF Binocular (Approx £130)
Nikon Aculon A211 10 x 50 Binocular (Approx £69-£95)
Helios Stellar-II 10x50 Binocular (Approx £150)

Are the Action EX or Stellar II worth the extra over the Aculon?

Many thanks if you take the time to reply,

Emma


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PostPosted: Fri Sep 25, 2015 1:17 pm 
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Location: Lancashire
I'm not a binocular expert Emma, but how do you propose to use the bins? Will you handhold them, or attach them to a tripod or binocular pantograph?
When hand-held, binoculars register every heartbeat, unless image-stabilised. A great improvement I made for steadiness was to make a triangular frame, with the bins attached to a bracket at the top and with bicycle hand grips at the bottom. It's possible to buy binocular holders, but it's cheaper and more fun to DIY. :D
There's also the binocular mirror-mount, the ultimate in comfort, that avoids a stiff neck. Mine's homemade, but they can be bought. We look down through the binoculars onto a tilting first-surface mirror. Some don't like the inverted image produced by a mirror-mount, but the Newtonian reflector gives an inverted image, and using a star diagonal with a refractor reverses the image!
A 7X50 binocular gives a steadier field when hand-held, but some prefer a bit more magnification.

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PostPosted: Fri Sep 25, 2015 1:33 pm 
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I cannot answer the actual question that you ask but I would suggest that you really need to try before you buy. You have well understood some of the important factors to consider but it is important to see which you actually feel most comfortable using. I checked in "Stargazing Basics" by Paul E Kinzer , and he recommends this too as, to quote...they vary not only in quality and optical design but in weight and shape, and so do human faces. He goes on to cite the case when he bought a pair of highly regarded binoculars but could not use them because that did not fit his face comfortably. regards mike


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PostPosted: Sat Sep 26, 2015 3:20 pm 
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I certainly agree, try before you buy. Also try them in dim light. I was surprised many years ago when, in dim light, a pair of cheaper binos out performed an expensive pair!

However most reasonable makes of binos perform OK these days.

David


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PostPosted: Sat Sep 26, 2015 5:46 pm 
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. Hi Emma and welcome.

If you wear glasses, you will have to make sure that there is sufficient eye relief.
Sometimes binoculars have too much eye relief for those who don't wear glasses, but not probably the 10×50 that you are considering. The manufacturers may quote eye relief.

The Action EX is waterproof.

I have the Aculon 10x42, which is good.

There is sample variation.

I presume your pupils open up to 5mm in your location.

I have not tried the Helios mentioned.

. The 10x50 Nikon Action VII also good.
. The Olympus DPSI and similar price Pentax 10x50 are reasonable.

I have not looked up the IPD measurements for any of these.

It is best to try these binoculars in a shop, as you can make sure that the collimation is good.

Also if you choose one, you should buy the one you test, and not an identical boxed binocular, as binoculars vary from sample to sample.

Regards, David


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PostPosted: Sat Sep 26, 2015 9:30 pm 
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Joined: Thu Sep 24, 2015 6:43 pm
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Many thanks everyone that's all really helpful advice.

I have decided to buy the book mentioned by Mike "Stargazing Basics" and "Stargazing with Binoculars" by David to get some more information.

In the meantime, I have decided to go for a cheaper / smaller pair to begin with - the Nikon Aculon 7x35 (sorry I didn't even mention that one to in my first post!) - to see how I get on with the weight etc... I can then make a more informed decision later on if I want to increase the magnification to 10x50 and possibly the budget to include a tripod.

I had to order online though as there didn't appear to be any stockists nearby to try any out.

Thanks again for the advice it is much appreciated.


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PostPosted: Wed Oct 07, 2015 11:07 am 
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Location: Surrey
Emma,

A couple of points - 10 x 50mm binoculars have a 5mm exit pupil ( 50mm/10 = 5mm). You need to still have 5 mm entry pupil to your eye if you are to use all the light, the size of your entry pupil falls with age. I think my talk to the SPA on human vision is on the site somewhere which covers this. I have attached the graph that shows how the average entry pupil falls with age. If your entry pupil is smaller than 5mm there is not much point buying 10 x 50 binos. This is also why middle age people cannot see the difference in brightness between 7x50 & 10x50.

A number of (older) people I know think the Canon Image Stabalised binoculars are very good for astronomy but then they probably have small entry pupils so the smaller exit pupil on the Canon binoculars does not matter to them.


Attachments:
File comment: Average entry pupil v age
Exit Pupil v Age.JPG
Exit Pupil v Age.JPG [ 83.49 KiB | Viewed 2888 times ]

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PostPosted: Wed Dec 09, 2015 10:03 am 
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Hi Emma,

Not sure whether you are still monitoring this discussion but this would be my advice on binoculars;

The exit pupil (aperture/magnification) should be at least 5. This applies particularly if you will be using them handheld. The exit pupil of the binoculars should match as closely as possible the diameter of the pupil in your eye when it is fully dark adapted. That means you will get the maximum efficiency in terms of image brightness.

With the above in mind that means that a pair of 7 x 50 or 10 x 50 would be ideal if you are a beginner. These would be light enough to be used without a tripod and will show you nice clear views.

Another size which has become popular in recent years are the 15 x70s which offer a larger aperture and magnification but with a slightly smaller (4.6mm) exit pupil. I use a pair of 15 x 70s which I got from Telescope House some years back for about £50. I can use these without a tripod for astronomy and general purpose viewing.

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