Buying Binoculars

[Spotty Albino]

Hi all, I'm looking to buy a pair of binoculars soon, and I've been researching the different aspects I should look for in an astronomy book of mine. I know where I stand with regards to apperture, magnification, coatings and cost etc., but the book mentioned entry and exit pupils, and I was wondering how important this is in choosing the correct binoculars?

As my eyes are likely to change alot while I use the binoculars for astronomy (I'm 15 now and apparantly pupil dilation changes alot with age), is it worth being picky about the entry/exit pupil sizes with regards to the binoculars I buy?

Cheers
Albino

[janoskiss]

Hi Albino. 7mm exit pupil should be fine for you under dark skies, 6mm under mediocre skies. But 7mm e.p. binos tend to have narrower true fields of view than those with around 5mm e.p. E.g. 7x50 and 10x50 tend to have about the same true field of view despite the diff in magnification. OTOH low power binos are easier to hold steady, which is why the 7x50 might appeal to you over the 10x50.

btw. How much are you looking to spend on the binos?

[Spotty Albino]

Hi, thanks for the info.

I was looking at spending around $300 on a decent pair so that they would last me a good while, and so that I get decent optics and light collection. Looking at around 7X-10X mag, probably an appature between 40-50mm. Field of view somewhere between 6.5 deg and 8 deg. Not yet sure what type of coatings i'll go with, but the book I was using for research said fully coated is the bare minimum for astronomy. I'll make a definate decision on coating once I'm at the shop and see what the price tags are like.

[janoskiss]

I can highly recommend the Fujinon 8x42 BFL for handheld use near that price point. I did a review of it for IIS. See: http://www.iceinspace.com.au/index.php?id=76,235,0,0,1,0

But do take my comments, positive or negative, with a grain of salt as my experience is rather limited.

[Nordo]

I'm a Newbie like yourself, but hanging around here I've learnt a few things.

1. There are several different types of coatings - some better for terrestrial viewing, some better for dark sky viewing. Ask or search in this forum.
2. I personally feel 7x or 8x is about the limit for hand-held. Above that you need a tripod or at least a soft spot to lie down, including supports for your elbows.
3. A few people here have built their own tripods for higher powered binos. It doesn't look too hard.
4. Have you read the two beginners articles by Iceman?
5. Regardless of your ongoing development (or decline) in astronomy, you will always use a pair of 7x50s.
6. If you wear glasses, you should also check a bino's/scope's property call "eye relief". This is the distance that your eyes can be from the eyepiece and still see the full "picture".
7. Above all else, if a salesman's speel differs from what the experienced people here tell you, then you know who to listen to don't you? Don't get sucked in by a salesman's {misspelt naughty word removed by moderator}:thumbsup: .
BTW, don't include me with "the experienced people":) .