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The Warthog

Eyepieces - the very least you need.

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I was so pleased to see this post. It's extremely clear and useful, thank you - not just the 'what', but the 'why' as well, which I really appreciate.

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Hi all , I have the skywatcher skyliner 200p. It comes with a 25 and a super 10 lens,

I want to get some bigger views of the planets , and other objects ,

I don't have a Barlow will this double the size of my current 2 len? Where can I find the perfect Barlow for my skyliner please ? What I e in particular can you recommend please link me ,

Finally I would like to buy 1 decent lens that's compatible , what should I go for please ? Thank you

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Great post, very interesting and informative for this fledgling amateur astronomer. The only real thing I've learned by experience so far is the inconvenience being a glasses wearer is! My optician said it was 'age related presbyopia' but I think she was just being polite. It makes having to take them on and off, in the dark, wearing gloves because it's cold, a bit tricky. I've concluded that this was why Patrick Moore wore a monocle.

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Since the forum reorganisation should this thread be moved into or linked to from Getting Started Equipment Help and Advice?

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Big thumbs up for the Celestron 7mm xcel llx , Had some nice clear skies and i could easily see the spot on jupiter and the bands :)

What barlow would you reccmonend to go with this eyepiece ?

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Thanks for the informative post - it will certainly help when buying time comes.

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Read a lot of good things about BST EPs, just saving up now for the three I need !

Sent from my Nexus 7 using Tapatalk 2

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Based on what a lot of members have said in regards to the BST range- 8mm and 18mm is a good staring point- in hindsight ,my recent purchase of the 25mm is also good but seems to suit my synscan mak 127 better then when used on my etx 90,,

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DOBSONIANS

Dobsonians tend to be large, fast scopes. If your Dob is 6" or less, you can safely follow the guidelines for the scopes listed above, as the highest magnification this will give you is 200.

At about 200x, it gets hard to follow things with a Dob. Some people can do it, and your ability to follow objects will improve with time, but 200x is a good start. You will want to have an eyepiece kit between 200x, and a 5mm (or 7mm if you are a youngster) exit pupil. Suppose you have a 10", f/5 Dob. You will have a focal length of 1250mm, and will get 200x with a 6.25mm eyepiece. In practical terms, a 6.5 to 7.5mm eyepiece will be what you will find available. To get a 5mm exit pupil out of a 250mm mirror, you will need an eyepiece that gives you 50x. This means a 25mm eyepiece. To get a 7mm exit pupil out of the same mirror means a magnification of 36, and a 35mm eyepiece.

Having decided on your low and high power, it is fairly easy to pick two more eyepiece focal lengths that will fill in the gap. If your spread is 6mm to 25mm, try 10mm and 16mm as your intermediate lengths. If the spread is 6mm to 35mm, then use 12mm and 20mm as your intermediate eyepieces.

So, for an 8" f/5 Dob, you would be getting something like a 5mm, 10, 16 and 25mm.

These guidelines will give you a useful set of eyepieces without breaking the bank. You can buy one eyepiece a month until you have your set, and use the eyeieces you have until your set is complete.If you can afford slightly better eyepieces, then buy those, with the length guidelines still in mind. If you have a fast scope, ask specifically if the eyepiece you are considering is appropriate for a fast scope. Some less expensive wide-angle eyepieces perform well only in a f/8 or slower scope, and you don't want to buy a set of these with a fast scope.

Hi all

A couple of years ago I managed to get a bargain Skywatcher Skyliner 300P which came with the standard 10mm & 25mm and an additional x2 Barlow. After speaking to a friend about eyepieces recently I feel the need to upgrade and replace mine. I've tried scanning the forums to get an idea of the best ones to get but I'm struggling. WH only went up to an 8" for his valid reasons and much as I tried to do the workings out I'm still unsure.

Thanks for any help.

Clint.

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Hi all

A couple of years ago I managed to get a bargain Skywatcher Skyliner 300P which came with the standard 10mm & 25mm and an additional x2 Barlow. After speaking to a friend about eyepieces recently I feel the need to upgrade and replace mine. I've tried scanning the forums to get an idea of the best ones to get but I'm struggling. WH only went up to an 8" for his valid reasons and much as I tried to do the workings out I'm still unsure.

Thanks for any help.

Clint.

Hi Clint,

You may want to post this question in the "Getting started equipment help & advice" section:

http://stargazerslounge.com/forum/186-getting-started-equipment-help-and-advice/

I think you will get more responses there.

Your scope has a focal length of 1500mm. You divide that by the focal length of the eyepiece to get the magnification. I have a scope of similar specification and I use eyepieces in the following focal lengths with it:

31mm, 20mm, 13mm, 8mm, 6mm and when conditions are good, 5mm. They give me a magnification range of 50x to 300x. The 31mm and 20mm are in the 2" size because I want wide angle views at those lower powers and 2" eyepieces allow wider views than 1.25" ones.

There are loads of brands available with prices from £40 - £500 per eyepiece (!).

I'm sure you will get lots of responses if you post the question again in the section I indicate above :smiley:

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Hi John and thanks for replying. Sorry I meant to say it was the 250PX not the 300P. Again, any help appreciated and I'll then go and dig myself a hole.

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Hi John and thanks for replying. Sorry I meant to say it was the 250PX not the 300P. Again, any help appreciated and I'll then go and dig myself a hole.

No problem - your focal length is 1200mm so the maths is a little different thats all !

The same eyepiece focal lengths would still be useful but they will just give slightly lower magnification eg 38x - 240x. You won;t need all those focal lengths that I have (I'm an eyepiece nutcase !) so something like 30mm - 15mm - 8mm - 6mm would be good. You don't need exactly those focal lengths but something close.

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Hi, and thank you for a great write up on eyepeices. I have just got myself a Dobsonian Revelation 12" telescope which came with a GSO 32mm wide field eyepeice. I have been lucky enough to have seen Jupitor a few times (only just made it out) but no other planets yet. What would you recomend for a better or closer view of planets, the moon and other great things to look for in the sky? Any help would be great as this is all new to me. thanks

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I have just bought a new low powered scope and wanted an ep that would suit my overal aim of having a travel outfit. So i got a zoom ep. There are lots out there but i got a celestron 8 - 24. If you are on a budget, then this is a good cost effective alternative.

(Sent from iphone)

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Just bought a Celestron Astomaster 130 (f/5) and thinking about eyepeices. It comes with 10mm and 20mm, and I'm not sure I've had a chance to use it in good seeing conditions yet (or how good my colimation is) - but maybe the 20mm is better than the 10.

Thinking about a 4mm eyepiece as the first thing to add - seems I can spend £40, or more. How much do I need to spend on this eyepiece to make it better than a 7mm with a barlow? It seems likely that I'll end up with 4mm and 7mm eventually, so the barlow seems like an option I can afford to skip...

Any particular brands to take a look at?

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Aha!

A fantastically informative first forum post find! I was getting a bit confused and overwhelmed with all the numbers and specs I've been reading about eyepieces and F numbers etc, not hard cos I'm easily confused, but this has helped.

Thanks for keeping this post at the top :-)

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What do you mean by a 'fast' scope?
A telescope with a small focal ratio, e.g. a f/4 scope is faster than a f/7 scope. The term comes from photography, where the aperture of s lens is given in terms of focal ratio, a greater aperture (short focal ratio) lets in more light, allowing fot shorter (faster) exposures.

On the batphone, so expect typos...

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Thanks for this, Warthog - just what I needed. I have an f/13 NexStar that came with the 25mm, so I now need a 9, 15 and 40.

Any ideas how I can get these past my wife?

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Thank you for such a straight forward and informative thread! Now I know for sure what magnification EPs I need for my scope.However, I can't afford televues as soon as I would like to, they do look very nice though and I'm still contemplating if I should spend more time saving and getting them or to go for some cheaper ones. I have read reviews, everyone seems to love them, but are televues really worth the price? Hope I'm not opening a can of worms here :)

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