h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

10 x 25 (although I'm not sure what that means).

The 10 is the apperture - the higher the better and 10 is pretty damn decent for star-watching. It means they gather a lot of light.

25 is the magnification. You don't want too much for sky watching because:
a) The higher it is, the more it cuts down on light
b) You can't hold binoculars steady enough for the magnification to be of any use.

Try leaning your elbows on a wall or something, to steady them, and try looking at the moon. You should be able to pick up some decent crater detail with those.

Here's what to look out for:
http://www.google.com/moon/

10 means the magnificiation. Things appear to be 10 times as close as they really are. For looking at stars, you really don't need big magnification because the stars look just the same at 10 magnifications or even 1000 magnification as they do without binoculars.

25 is the diameter of the big lens and means the light gathering ability. The bigger this is, the brighter the image will be, which doesn't matter much for looking at birds during the day, but is very important for looking at stars, as with more light gathering, you'll be able to see the stars clearer and to see stars that are normally invisible. 25 is a small value - you can get binoculars up to 50.

Wrong way round. Gnomon's right. As usual.

Ok thank you, I did think of leaning on the windowsill, but of course then I've got to look through the double glazing. I'll try again tonight if it stays clear, even if I have to take a chair outside and lean on that!

If you have a problem with the windows, Mina, you can negate most of the effect by wrapping a black plastic bag around the end of the bins and pressing a few inches against the window on each side. This will remove most of the reflections and improve the image quality considerably

I use white plastic bags in my bins . . . oh, I see, binoculars, sorry

I'd have thought you'd have been a composter.

Oh yes, that too.

And a compositor.

I came across a word for an odd-jobbing compositor in the dictionary the other day: Smoot.

I have made it my business name http://www.Andrew.Robinson.net

Another lovely starry morning this morning. The sky was a deep blue but the sun wasn't yet up. saw one meteor, which looked spectacular against the blue.

This morning was the Winter Solstice, so we're half way through Winter!

Heritage Ireland had set up a web camera to broadcast the sunrise in Newgrange, the 5,000-year-old tomb into which the sun shines for a few minutes at sunrise on the Winter Solstice. But the site appears to have been swamped by traffic and I couldn't get onto it.

Isn't the solstice tomorrow? What with next year being a leap year?

You're right! I mis-read the tables.

The solstice is 6:08 am tomorrow. Of course that's today if you live in Seattle or Los Angeles.

Am I the only member of this club (Gnomon's correctors)?

Hi gnoman,

Perhpas you could advise me what sort of Telescope and/or binoculars to get for my beautiful new home overlooking the Channel. We are just twenty miles from France and it would be super to be able to look at the marine(?) traffic passing. Also occasionally to look up at the sky although I cannot remember all the constellations.

Best wishes to you you and yours for Christmas and the New Year.

Sincerely,

christiane.

Hi Christiane!

Binoculars have two numbers with an x between them, such as 7 x 50 or 10 x 30.

The first number is the magnification. It should be between 7 and 10. The higher the number, the bigger things will look, but the more wobbly the image will be, so I recommend you get 7 or 8 if possible.

The second number gives the diameter of the lens, which indicates the light gathering ability and also indicates the weight. It is typically between 25 and 50. For daytime use, this number doesn't matter much but in dim light or at night you want it as big as possible.

But the problem is that big lenses weigh a lot more than small ones. If your arms are strong, and you don't mind carrying weight, then get 7 x 50 binoculars. These are the best all-round binoculars for every purpose. If you are not up to carrying heavy binoculars, you could go for the much lighter 8 x 30 ones. These will be just as good for looking at boats in the channel, but not so good when it comes to looking at the stars.