Astronomy

[gavroche]

Anyone interested in it and what advice can you give me? My wife bought me three telescopes and tripod for my birthday. I am very pleased with it but don't really know which telescope to use and when. They are SkyWatchers . One is D 127mm F1500, then D102mm F1300mm and D102mm F500mm. I understand D is diameter of lens and F the focal length .There are also many eye pieces and the tripod has a electric control for rotating and adjusting height. I am very keen to take a close look at the moon,mars , Venus and Jupiter but the sky is always cloudy at night at the moment . I am also thinking of joining an astronomy class in my local college where I work. I know the teacher very well.

 

[Stephenite]

Lucky chap. I suggest you join the class.

 

[Stephenite]

[QUOTE 3992288, member: 9609"]Venus Jupiter and Mars are all very close to each other just before break of day, worth taking a look at. In fact tomorrow morning 5:30 ish a quarter moon will also be joining them.

This site
http://neave.com/planetarium/
is excellent for locating starts and planets[/QUOTE]
This is true. I'm up at this time, more often than not, due to the kids. Haven't managed to see them yet though. I'd have to go out, and leave the kids to smearing one other in porridge, as it's a bit low on the horizon here.

 

[Hugh Manatee]

If it is anything like mine, once you have got your telescope, most of the action is with the eyepieces. With mine, (a Celestron) it works like this:

The eyepiece is sold in terms of mm sizes. For example, I have 5mm, 10mm and 20mm ones. I think this measurement refers to the diameter of the lens you look through on the eyepiece. The lower the number, the higher the resulting magnification. The whole of the full moon fits into the view using the 20mm eyepiece but with the 5mm one only a small part of the moon is visible but obviously in a lot more detail.

Get really low numbered lenses then to see far away planets? Maybe not. You need better quality telescopes to handle the higher magnifications, (better mirrors etc). There is also "eye relief" to consider. This is the strain caused by the much higher magnifications. My 5mm is as low (high?) as I want to go. It will pick out the moons around the gas giants though.

Enjoy it. It is a fascinating solar system out there.

 

[Neilsmith]

There are some excellent apps for smart phones and tablets that can show you what's above and in which direction well worth a look

 

[gavroche]

I have an app on my tablet called: "Distant Suns" It seems to be pretty good.

 

[Drago]

Norton's Star Atlas. A very old school book, bit still one of the best if you can find one.

 

[sight-pin]

Anyone interested in it and what advice can you give me? My wife bought me three telescopes and tripod for my birthday. I am very pleased with it but don't really know which telescope to use and when. They are SkyWatchers . One is D 127mm F1500, then D102mm F1300mm and D102mm F500mm. I understand D is diameter of lens and F the focal length .There are also many eye pieces and the tripod has a electric control for rotating and adjusting height. I am very keen to take a close look at the moon,mars , Venus and Jupiter but the sky is always cloudy at night at the moment . I am also thinking of joining an astronomy class in my local college where I work. I know the teacher very well.

I used to frequent 'The Stargazers Lounge' It's the biggest astronomy forum in the UK, It's a very good forum, you'll obtain a mine of info there.

Edit, Also take a look at 'Cloudy Nights' That is the biggest American forum, also highly recommended.

 

[sight-pin]

When you do find a clear night, take a look at the M42 nebula in Orions belt which is about this time of the year, try about 40 magnification, you won't see hardly any colour as our eyes don't pick that up but it's a nice one.

 

[captain nemo1701]

Lucky man, having three refractors!.

To undesrtand which scope is best depends on what you want to look at. Refractors are generally good for the moon & planets. To calculate the magnification, just divide the focal length of the eyepiece into the focal length of the scope.

For distant objects , you need higher magnification that will allow you to see, say, neptune's disc and will also seperate double stars. So I'd use your 1500mm scope with a 10mm eyepiece, which is 1500/10 or 150x magnification. However, high magnifications with high focal lengths narrows your field of view, so objects cross the field (due to the Earth's rotation) seemingly quicker. If you're lucky to have a compterised Go-To scope, they can track objects on their equitorial mounts with servo motors. Other wise, you'll have to do it manually.

For more general star gazing, moon & planets, use your 500mm scope with a 25mm or 32mm eyepiece, which gives you between 500/25 or 20x mag and 500/32 or about 15x mag which should be enough to give you great views of the moon, show the moons of jupiter and saturns rings. And the field of view is nice and wide, meaning that you won't have to adjust the scope as much to track objects.

Longer focal length + shorter eyepiece focal length = higher magnification = narrower field of view

Shorter focal length + longer eyepiece focal length = lower magnification = wider field of view

You have three scopes to play with, so I'd just fiddle around until you find which best suits you. I'd go for the 500mm scope to look at the moon and maybe your 1500mm scope for more distant objects. A good selction of eyepieces would be say, 5,10,20,32mm which, when used with both scopes, will give you a good range of magnifications and varying field of views. I generally use longer focal length eyepices to initially locate planets and then pop in a 5mm eyepiece to boost the magnification.

Use longer focal length eyepieces with the 500mm scope to provide a wide field of view to observe nebulae and galaxies. Unfortunately, unless you are lucky to live out in the countryside away from light polluted skies, deep sky observing is difficult.

Here's some good sites to visit:

http://stargazerslounge.com/

http://www.popastro.com/

 

[Zeffer]

Another endorsement of Stargazers Lounge. Superb advice always. I have a Meade 8" GPS scope and a 6" Celestron, but still find myself returning to the classic targets: M42, Saturn, Jupiter, the Double Cluster and the brighter globulars (e.g. M13). I tend to end on the moon as it's utterly blinding but magnificent.

 

[gavroche]

Lucky man, having three refractors!.

To undesrtand which scope is best depends on what you want to look at. Refractors are generally good for the moon & planets. To calculate the magnification, just divide the focal length of the eyepiece into the focal length of the scope.

For distant objects , you need higher magnification that will allow you to see, say, neptune's disc and will also seperate double stars. So I'd use your 1500mm scope with a 10mm eyepiece, which is 1500/10 or 150x magnification. However, high magnifications with high focal lengths narrows your field of view, so objects cross the field (due to the Earth's rotation) seemingly quicker. If you're lucky to have a compterised Go-To scope, they can track objects on their equitorial mounts with servo motors. Other wise, you'll have to do it manually.

For more general star gazing, moon & planets, use your 500mm scope with a 25mm or 32mm eyepiece, which gives you between 500/25 or 20x mag and 500/32 or about 15x mag which should be enough to give you great views of the moon, show the moons of jupiter and saturns rings. And the field of view is nice and wide, meaning that you won't have to adjust the scope as much to track objects.

Longer focal length + shorter eyepiece focal length = higher magnification = narrower field of view

Shorter focal length + longer eyepiece focal length = lower magnification = wider field of view

You have three scopes to play with, so I'd just fiddle around until you find which best suits you. I'd go for the 500mm scope to look at the moon and maybe your 1500mm scope for more distant objects. A good selction of eyepieces would be say, 5,10,20,32mm which, when used with both scopes, will give you a good range of magnifications and varying field of views. I generally use longer focal length eyepices to initially locate planets and then pop in a 5mm eyepiece to boost the magnification.

Use longer focal length eyepieces with the 500mm scope to provide a wide field of view to observe nebulae and galaxies. Unfortunately, unless you are lucky to live out in the countryside away from light polluted skies, deep sky observing is difficult.

Here's some good sites to visit:

http://stargazerslounge.com/

http://www.popastro.com/

Great info there Captain Nemours 1701. Thank you for that. I will check which eye pieces I have , now that you have explained it.

 

[jiberjaber]

This is also pretty good as it allows you to work out what you can see and when /where to look - I mostly use it to see what space object I've just seen whizzing across the sky

http://www.stellarium.org/en_GB/

I got in to astrophotography quite a bit at one point too, but the hours for me are not compatible with a fulltime job really

I should really sell my gear, as its just not getting used.

 

[Drago]

Been thinking of getting back into it, going to have a go at building a radio telescope.

 

[Profpointy]

If it is anything like mine, once you have got your telescope, most of the action is with the eyepieces. With mine, (a Celestron) it works like this:

The eyepiece is sold in terms of mm sizes. For example, I have 5mm, 10mm and 20mm ones. I think this measurement refers to the diameter of the lens you look through on the eyepiece. The lower the number, the higher the resulting magnification. The whole of the full moon fits into the view using the 20mm eyepiece but with the 5mm one only a small part of the moon is visible but obviously in a lot more detail.

Get really low numbered lenses then to see far away planets? Maybe not. You need better quality telescopes to handle the higher magnifications, (better mirrors etc). There is also "eye relief" to consider. This is the strain caused by the much higher magnifications. My 5mm is as low (high?) as I want to go. It will pick out the moons around the gas giants though.

Enjoy it. It is a fascinating solar system out there.

Not quite right, but conclusion is along the right lines..

Magnification of a telescope is the focal length of the telscope itself, divided by the focal lenght of the eyepiece.
Telescopes are usually described by the diameter (not focal lenght) and an f number - which is the multiple of the diameter which gives the focal lenght. Thus a 100mm f8 has a focal length of 800mm.
(Camera lenses on the other hand are focal lenght and f number thus the same thing would be quoted 800mm f8)

The maximum usable (before it goes very fuzzy) magnification of a combination is usually quoted as 50 or better 40 per inch of aperture, and not much more than 200x regardless of aperture.

Thus a 100m telescope could magnify up to 200 at a stretch. So, the same 100mm f8 telescope (800mm focal length remember) could take an eyepiece as short of 4mm just about - giving 200x magnifaction in good conditions.

High magnification is good for planets and craters on the moon - lower for galaxies and nebulae, milky way, start clusters.
The higher the magnification, the dimmer the image and galaxies / nebulae are dim and diffuse so no use mangifying lots.
Higher magnification is obvously more wobbly and things whizz across the skye quickly

One handy hint - spend a lot on the tripod - apparently the experts often spend as much or more on the tripod as the scope.
I got a £500 tripod for my 100mm refractor (I was lucky enough to get it fairly cheap on ebay) and it's a vast improvement on what I had before.
If the image is wobbling about, there's not point having great optics.

Anyway, hope this makes sense