Eye piece for 8 inch skywatcher dob

[broom]

Just a quick one.

i have £60 to spend on equipment. I have a new 8inch dob and was thinking of spending it on eye pieces. 

Can you recommend a decent upgrade for that price? I was thinking the celestron xcel but I was hoping to get 2 for £60. 

thanks

darrell

[Putaendo Patrick]

What sort of focal length are you thinking for your EPs?

[Jamie16v]

I can`t recommend anything as i`m a newbie also but i too have had my eyes on the celestron x-cel range and i think that`s what i am going to stick with after hearing nothing but good about them. 

[broom]

2 minutes ago, Putaendo Patrick said:

What sort of focal length are you thinking for your EPs?

I was thinking of keeping the stock 25mm for the time being. Purchasing a new 18mm and 9mm. 

[alanjgreen]

Broom,

the 25mm gives x48 times magnification in you scope.

18mm will give you x66

x50 and x66 are too similar, you will see no difference

you will be better with 8mm which is x150

then get something at x100 which is 12mm! 

So 25, 12 and 8 are a better spread.

 

To calc the magnification, divide 1200 (your scope focal length) by the size of the eyepieces (25,12,8)

 

Alan

[alanjgreen]

Skywatcher plossls around 25 quid are a good starting point and will be much better than those supplied with the scope.

Unless you wear glasses then celestron xcel are great with a longer "eye relief".

- eye relief value tells you how close you need to place your eyeball to the eyepiece, glasses wearers need more...

[Putaendo Patrick]

There are (at least) three important factors in choosing an EP - optical quality, field of view and eye relief. These factors are determined by the eyepiece design and by price.

With your telescope you should get acceptable results with Plossls - Celestron Omni and Revelation both do 9mm at about 20 - 25 pounds. Celestron also have a 15mm which might fit the bill. The downside is relatively narrow field of view (about 50°) and quite tight eye relief on the 9mm. You could buy both and still have change within your budget.

https://www.firstlightoptics.com/celestron-eyepieces/celestron-omni-plossl-eyepiece.html

https://www.telescopehouse.com/eyepieces/revelation-eyepieces.html

The Vixen NPL range are better quality Plossls at about 35-45 pounds each. They do an 8mm or 10mm and a 15mm or 20mm. Better optical quality but the same disadvantages as above. You could pick up two for 70 pounds - not to far over the budget! https://www.telescopehouse.com/eyepieces/vixen-eyepieces/vixen-plossls.html

BST Starguiders (also branded as BST Explorer and in the USA as Paradigm) are another step up, and in my opinion represent better value than Celestron X-Cels. Available in 8mm and 15mm or 18mm at about 45 - 50 pounds. These have a noticeably wider 60° field of view and more comfortable eye relief. Excellent value and highly considered on this forum! http://www.365astronomy.com/Planetary-Eyepieces/

Although limited to 50° field of view, a favourite EP design for me is the Orthoscopic. Baader Planetarium do a range of Classic Orthos at about 50-60 pounds each. Available in 10mm and 18mm. https://www.firstlightoptics.com/baader-planetarium/baader-classic-ortho-bco-eyepiece.html  The 10mm would be an excellent planetary eyepiece.

Most of these eyepieces do come up for sale second-hand from time to time so it's worth keeping an eye out on sites such as http://www.astrobuysell.com/uk/

Older eyepieces can also be good value in the second-hand market - for example older Japanese-made Meade 3000 or 4000 series in the 9mm range. These are great Plossls or modified Plossls and turn up quite cheap!

Another option worth considering is a Barlow. This effectively magnifies the power of an EP by a factor - for example x2. Thus an 18mm eyepiece with a x2 Barlow would give the same as a 9mm. Barlows are an economic way to extend your range of magnifications as you build up your EP collection.

 

 

 

[alanjgreen]

Very true Patrick.

you could get the £25 plossls now, then watch on the classifieds for the baader classic orthos to come up - I can see a 6mm baader in the for sale section now for £35...

best bet to get 3 decent eyepieces to get you going I would say, if you stay in budget then even better 

[broom]

Thank you all for your detailed responses.

I actually wear glasses and only have vision in one eye. As a result, should I be looking at eye pieces with greater eye relied such as the BST starguiders?

[Louis D]

10 minutes ago, broom said:

I actually wear glasses and only have vision in one eye. As a result, should I be looking at eye pieces with greater eye relied such as the BST starguiders?

Do you have strong astigmatism?  If so, they yes, you'll need to wear your glasses at lower powers for certain.  At higher powers (smaller exit pupils), you might find you don't need to wear glasses because astigmatism is strongest in the outer parts of the human eye's pupil.

What's your cylinder correction on your vision prescription?  We can give anecdotal reports based our own correction relative to yours then.  If you don't have any astigmatism, you can just focus out your near or far sightedness at the focuser without glasses.

[triton1]

+1 for the BST starguider good value for money for a very capable eyepiece should work very well in your scope.

[LukeSkywatcher]

BST's are within your budget and have the eye relief you want/need. You have a 25mm EP which works for you?. You should maybe think about a 15mm and an 8mm.

[LukeSkywatcher]

"There are (at least) three important factors in choosing an EP - optical quality, field of view and eye relief".

Of all 3......i would say eye relief is the most important. Optical quality can be had in a £30 plossl just as a £300 plossl (Love my Vixen NPL's). FOV only comes into play when switching between 1.25" and 2"......(NOT STRICTLY TRUE).

Eye relief is the big one. I get on so well with the eye relief on the Vixen NPL's, when so many others find it a major issue.

[Charic]

Do you need to buy two straight away and  potentially limit your budget!  you could buy just one, and if you like, buy another later, its going to happen one way or another, but the truth be told, only your eye will decide if its good enough for you ?

The revelations are cheap to buy, even cheaper second hand?  their eye relief is short, so you may have an issue if you must wear your glasses at the scope. I have prescriptions for distance and slight astigmatism but choose not to wear them at the scope,  but those GSO Revelation Astro's  are  good, very good, much cheaper than my Tele Vue and  Meade  Plössl's  and with a resonable with 52° afov. 

Stepping up the afov to 60° with  a 12mm is a good bet, the BST Starguider in particular.  The  12mm  hits the sweet spot (the point at which a scope is supposed to be at its optimum - Skyliner 200P  ) and you could  2x Barlow the 12mm for the equivalent of using a 6mm, another choice of mine for obtaining 200x power. The 8mm Starguider, also a top choice  for the 8" Dob.

There are elements that may be of interest to you regarding Tele Vue's Delos range, very expensive new, but their 20mm eye-relief and their Dioptrx corrector lens may be of interest to you, but honestly, a Delos is not required to get good results on an 8" f/6 scope, the BST's will satisfy, if not send them back, refund, sorted! At least you tried.

I  can sit here all night ( at present its too  windy  to be out observing ) saying whats best for you, but only after testing for yourself, will you find the solution. We all love our eyepieces, and will swear by them, even at each other ( not allowed ) but  eyepiece selection is  always one of the hottest topics, and we all just want to help, its down to you from here on.

And welcome to the SGL.

[broom]

Thanks all, I really appreciate the responses.

i'm short sighted and have to use glasses all the time. I can't remember my exact eye prescription however, I do recall something about -6.75. 

in the end I have opted for the BST 15mm only. I'll see how I get on with that eye piece and if successful, I will purchase a 10mm next month. 

Just waiting for clear skies now to get out.

Again, thanks for the responses.

[Putaendo Patrick]

Good luck with the 15mm BST - seems like an excellent choice!

As you use glasses, a feature of Barlows worth remembering is that they maintain the eye relief of the original eyepiece. So there may be times when it is better for you to use, for example, a 20mm EP plus x2 Barlow rather than a 10mm eyepiece.

It may be useful seeing if there are any astronomical clubs in your area and attending a viewing night. You will have the opportunity of looking through different telescopes, and eyepieces, belonging to members - and this may help you to identify EPs that work well with you. This thread may be a little out of date, but will perhaps give you some leads:

 

[Charic]

If your a 'set' type of person, likes to collect, and if your looking to stay with a brand, the BST Starguider range does not include a 10mm eyepiece. 
For this reason I own the William Optic 6mm (no BST equivalent)  to compliment the focal ratio of my scope, f/6.

[Jimtheslim]

5 hours ago, Putaendo Patrick said:

 

Although limited to 50° field of view, a favourite EP design for me is the Orthoscopic. Baader Planetarium do a range of Classic Orthos at about 50-60 pounds each. Available in 10mm and 18mm. https://www.firstlightoptics.com/baader-planetarium/baader-classic-ortho-bco-eyepiece.html  The 10mm would be an excellent planetary eyepiece.

 

 

 

 

I absolutely adore my 10mm Baader Classic Ortho (I'm sure most members on here are sick of me bleating on about it to be honest). But I always recommend people consider an ortho, especially for a faster focal ratio scope. You can usually find them for about £35 second hand. I would say you should always check for used eyepieces. People tend to keep them in pretty much 'as new' condition. The sharpness, contrast and detail they seem to bring out is just unlike anything I have seen before. if you don't wear glasses and don't mind the small field of view then give orthos some serious consideration

[Louis D]

4 hours ago, Jimtheslim said:

I absolutely adore my 10mm Baader Classic Ortho (I'm sure most members on here are sick of me bleating on about it to be honest). But I always recommend people consider an ortho, especially for a faster focal ratio scope. You can usually find them for about £35 second hand. I would say you should always check for used eyepieces. People tend to keep them in pretty much 'as new' condition. The sharpness, contrast and detail they seem to bring out is just unlike anything I have seen before. if you don't wear glasses and don't mind the small field of view then give orthos some serious consideration

Have you compared you BCO to either a 10mm TV Delos or Pentax XW?  I have the 10mm Delos and find it absolutely astigmatism free across the field even at f5 without a coma corrector.  The background is inky black as well.  Contrast seems excellent on planets.  I've never owned an ortho because I'm not sure any non-Zeiss ortho is going to be an improvement over the Delos.  That, and I need eyeglasses to correct 2 diopters of astigmatism, so using a 10mm ortho could be difficult as well.

[Louis D]

6 hours ago, broom said:

i'm short sighted and have to use glasses all the time. I can't remember my exact eye prescription however, I do recall something about -6.75. 

You will definitely want to wear eyeglasses at the eyepiece so you can quickly look up at the sky or your star charts without having to take glasses on and off.  Some folks with mild near sightedness can still make out bright stars and easily read charts without glasses, but that is not the case here.

[Jimtheslim]

5 hours ago, Louis D said:

Have you compared you BCO to either a 10mm TV Delos or Pentax XW?  I have the 10mm Delos and find it absolutely astigmatism free across the field even at f5 without a coma corrector.  The background is inky black as well.  Contrast seems excellent on planets.  I've never owned an ortho because I'm not sure any non-Zeiss ortho is going to be an improvement over the Delos.  That, and I need eyeglasses to correct 2 diopters of astigmatism, so using a 10mm ortho could be difficult as well.

No and it's unlikely I ever will unless they start growing on trees. But given the OP has a budget of £60 I felt it was a fair comparison to eyepieces that fit into that price bracket, which I have tried. I find people seem to try the eyepieces that come with the scopes and start to get itchy for something that they feel will deliver more. They look at the array of things on offer and want to start spending money. Given they have started off with tight eye relief and small fov I don't think you can really go too far wrong with an ortho if people can live with the it. I can imagine that once you've owned eyepieces offering dazzling field's of view sharp image quality to go with it, it becomes the only thing you would want. However forking out hundreds of pounds on a single eyepiece is something some people just cannot, or are not willing to do so early on in the hobby.

[rwilkey]

16 hours ago, broom said:

Thank you all for your detailed responses.

I actually wear glasses and only have vision in one eye. As a result, should I be looking at eye pieces with greater eye relied such as the BST starguiders?

Hi there, yes, the BST Explorers/StarGuiders would suit you and your telescope well.