Can somebody explain eyepieces

[claire1985]

I have a 6mm and 10mm eyepiece for my scope but to be honest I really don't understand them, I tried looking at the moon through the 10mm and couldn't see anything and blinded myself :-/

What's the best for looking at planets and the moon?

Before anybody answers can I just note I have had a total of 2 hours sleep as I have a very poorly 2 year old so please keep it simple :-)

X

[Mattscar]

What scope do you have? From what I can tell 10mm and 6mm are good ones for planets. As for the moon, not sure whats going wrong as I have 25, 18, 10 & a barlow and get awesome moon views through all the combinations.

[alan potts]

Before anyone can give you an answer we need to know what scope you are using becaise the same eyepiece will give different magnifications on different telescopes.

This would be better in eyepieces, would one of the Mods care to move it then it will get better attention.

Alan

[wookie1965]

basically the lower the number on the eyepiece the higher the magnification and the opposite the bigger the number the lower the magnification.

example my scope has a focal length of 750mm divide that by an eyepiece of 25mm gives me 30x where as a 10mm will give me 75x. here is a good site for formulas

http://www.astro.shoregalaxy.com/index_010.htm#1

[bingevader]

As to the "blinding" bit, the moon is the brightest night time object and way brighter than anything else in the sky at night.

Some people do find it too bright through a 'scope especially when full.

You can add a moon filter if you find it too bright, but for most of the phases of the moon, your eyes usually get used to the brightness.

Afterwards, it can be a bit like having looked at the sun in daylight (not through a 'scope!) or at a light bulb, with the image imprinted on your retina for a few seconds/minutes.

CHeers

[claire1985]

Ah sorry should have said.

I have a Celestron Nextstar 5 SE

Thanks for the info guys, I'm such a noobie lol xxx

[Mattscar]

Nothing wrong with asking basic questions If you dont know the basics, how can you learn the more advanced stuff?

When I first looked at the moon I thought it was too bright and that I was going to do damage to my eye's if I kept looking at it, now however I'm more used to it and its not as much of a surprise to my brain so its not too much of an issue now. I don't know about moon filters, but I can certainly recommended looking at the moon through a light pollution filter, I didn't realise how yellow it looked without one untill I tried it, however that does depend on how much LP there is.

[Carl Reade]

I'll have a go, Eyepieces are a glass lense which allows you to see an object your scope is pointed at clearly and focused at different magnifications. They come in various sizes. The smaller the size in mm the higher the magnification.

For planets you generally need high magnification as they are small. The moon not so much needed.

To work out the magnification you do it this way. Your scope will have a focal length which it should say on it or you can find out via google. You then divide the focal length by the size of the eyepiece. For instance my scope has a focal length of 750mm, so with a 10mm eyepiece inserted that gives me a magnification of 75 times. So the object Im looking at is 75 times larger.

If I use a 6mm eyepiece then the object is magnified 125 times. 750 divided by 6.

When you place the eyepeiece into the scope you have to use the focus knob on the scope to bring the object into focus so you have a clear image and can see what your looking at. I suspect as the moon is bright you hadnt used the focus knob and then it would appear as a bright light.

Try pointing the scope at something outside or through a window then pop in an eyepiece and then turn the focus knob until you get a clear image (something far off).

If you change eyepieces you will also have to refocus.

Hope this helps

Cheers Carl

[alanjgreen]

Or just put some sun glasses on!!

[John]

To keep it simple, the longer the focal length of the eyepiece is , the lower magnification it produces. So your 25mm shows a less magnified image than your 10mm. To find out how much magnification an eyepiece gives you divide the focal length of your scope (1250mm in the case of your Nexstar 5) by the focal length of the eyepiece. So the 25mm eyepiece gives 50x and the 10mm eyepiece gives 125x.

It's usual and useful to have a small range of eyepieces so you have low, medium and high powers to use as needed. With your scope, low power might be 25x-40x, medium power might be 60x-100x and high power could be 130x-200x or even a wee bit more on occasions. These are just guidelines, not firm rules.

To see detail on the moon and planets its usual to use higher magnifications. To view deep sky objects (galaxies, nebulae, clusters) low to medium magnifications are usually used.

Does that help a bit to start with ?

PS: while they can look bright, you can't damage your eyes looking at the moon or the brighter planets.

[claire1985]

That helps loads!!! I've never really understood eyepieces so trying to learn now I have some to play with :-) x

[bomberbaz]

Hi Claire. Not sure if you have a budget to spend but I use now a variable polarizing filter. It does not change the moons colour but it does reduce the light hitting the back of your eye and so its less bright but really does improve detail and contrast. By how much it alters the view you can decide as it is adjustable. They are not the cheapest item but they are very good.

http://www.firstlightoptics.com/moon-neutral-density-filters/variable-polarizing-moon-filter.html

Actually £30 for the 1.25 is very good. Miles better imho than a standard moon filter.

[Stargazer_00]

I love moon blindness. brighter the better. nothing like walking away from your scope after a 20 minute stare at the moon. you have one dark adapted eye you use to navigate and one almost entirely blind eye. hardcore!

[bomberbaz]

I love moon blindness. brighter the better. nothing like walking away from your scope after a 20 minute stare at the moon. you have one dark adapted eye you use to navigate and one almost entirely blind eye. hardcore!

crazy man, lol ;p

[Monty]

Try this for a guide.

http://www.saguaroastro.org/content/EYEPIECE.htm

[claire1985]

I love moon blindness. brighter the better. nothing like walking away from your scope after a 20 minute stare at the moon. you have one dark adapted eye you use to navigate and one almost entirely blind eye. hardcore!

I only have one eye anyway, got astigmatism in my right one and can't see anything lol x

[peeceeTal2M]

If your budget allows i'd definitely go for a polarizing filter, far more flexible than the normal moon filters in my opinion and once you've adjusted it to your liking you can observe the moon for hours without discomfort

[Doshy]

Or just put some sun glasses on!!

Brilliant! why didn't I think of that. Stumbling back towards the house, tripping over the dog and nearly falling in the pond was my last experience having alternated between both eyes looking at the moon. The scope came with one of those LP filters but only for the smaller lenses not the 2" bad boys.

Gotta wear shades.......

[theironduck]

Hi Claire, fellow 5se owning noob here! I got my first look at the moon the other day too. This is what I did:

- Use red dot finder to get scope pointed in right direction

- Activate the lunar tracker ("Solar System Align -> Moon" I think)

- Start with 25mm EP (that came with the scope) which should let you see the whole of the moon, making it easier to find and focus on.

- Swap to higher power EPs to look at details

A couple of other things to note:

1) As you are wearing glasses you will probably find the eye-relief better on the 25mm than on the 6mm and 10mm EPs i.e. you will not have to get your eye/glasses quite so close to the EP. I can imagine the eye-relief on the 6mm might be quite tricky with glasses.

2) You will probably need to refocus every time you change between EPs (unless you have a fancy parfocal set which use the same focus).

[tenbyfifty]

in case nobody else mentions it :

if u plan on getting better quality eps at some point make sure they are (excuse the techno babble) PARFOCAL

which means that u don't have to alter the focus when u swap between eps, a major source of frustration in my limited experience as u have to wait for the scope to settle down each time u change the ep. i don't actually own any myself but i'm confident people on this forum who do will swear by them. ofcourse the eps u have may already have this shared feature but as i said, just thought i'd bring it to your attention before u spend any money.

[DanH]

I am a bit surprized that nobody told you this, especially because you are discovering astronomy : NEVER LOOK AT THE SUN !

You would be blind forever in a fraction of a second !

And, if there are kids in the vicinity, never leave a telescope unattended outside during the day, for the same reason.

One used to say : you can only look at the sun twice in a lifetime with a telescope: once with the left eye, and once with the right eye !

There are accessories to enable sun watching, some are very cheap like the Baader Astrosolar foil !

[starman1969]

The Celestron Nexstar 5se is a very posh scope. You will get some great views of planets with it.

I'd stick to the 25mm for the moon. The whole disc should fit in the eyepiece.

[bomberbaz]

Claire Do you wear your glasses when you view? If si, then you might be havinhG problems due to eye reliag on you basic eps . Believe me I could write a bloomin book on eo's for specs wearers But if you do, that could be a oart of uour oroblem!

Sry for typos on a Rubbish pad

[claire1985]

Sorry guys I've been really poorly so not had chance to catch up on this thread, I'll look through all the replies when I'm feeling better, thanks for all the advice though

Xxx

[LukeSkywatcher]

The 10mm EP should give nice views of the Moon and Jupiter,Saturn. The 6mm will most likely only give great views of the Moon.

The 10mm and 6mm EP's that Claire has came from the Celestron "Eye Opener" Kit.