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Eyepieces for fast telescopes?


Eren

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I have a skywatcher 10" dobsonian, f/4.7, and am looking for some good quality (but not too expensive) eyepieces. I've been looking at the explore scientific 82 degrees eyepieces and am wondering if anyone has had any experience with them. Also, is it worth the money to get 2" eyepieces instead? I don't have a lot of money but would rather save up and not have to buy another for a while, the first will probably be the 4.7mm or 8.8mm (will get a 2x barlow if I get the 8.8mm) and gradually get the ones I need over the next couple of years.

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First, what is your budget.  Second, what eyepieces do you already have?  To your question, the ES-82, ES-92, ES-100, and ES-120 lines all do fine at f/4.7.  Televue advertises that they test their eyepieces down to f/4.  Pentax XWs also do fine in fast scopes.  At the cheaper end, you could also try the shorter focal length Starguider, Celestron X-Cel LX, and Meade HD-60 eyepieces.

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The ES 68's and 82's (and the 100's) do pretty well in faster scopes. Another decent option are the William Optics UWAN / Skywathcher Nirvana's - some sold on here for £60 apiece recently.

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19 hours ago, Red Dwarfer said:

I have the Explore Scientific 8.8mm and it is great for clusters and other DSOs ... It Barlows very well too and the Ring Nebula is excellent . 

Do you have any recommendations for good 2x barlows? The Ring nebula was my first ever DSO:icon_biggrin:

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11 hours ago, John said:

The ES 68's and 82's (and the 100's) do pretty well in faster scopes. Another decent option are the William Optics UWAN / Skywathcher Nirvana's - some sold on here for £60 apiece recently.

Thanks, I'll have a look for them

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12 hours ago, Ben the Ignorant said:

My 4.7mm Explore performs very well with my f/5 dobsonian. Sharpness and clarity are excellent to the edge; lateral color is very mild.

I was worried about aberration so that's good to hear

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12 hours ago, rockystar said:

I'd get the 8.8 first, rather than the 4.7 - it will get far more use. I've got the 24mm version which I think is a great EP, but u am only using it at F/6

I think I might leave the 4.7mm then and instead get the 2x barlow

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19 hours ago, Louis D said:

First, what is your budget.  Second, what eyepieces do you already have?  To your question, the ES-82, ES-92, ES-100, and ES-120 lines all do fine at f/4.7.  Televue advertises that they test their eyepieces down to f/4.  Pentax XWs also do fine in fast scopes.  At the cheaper end, you could also try the shorter focal length Starguider, Celestron X-Cel LX, and Meade HD-60 eyepieces.

I'd like to keep it around 150ish, means I will be able to have the money around November or wait encase there are any sales around Christmas, Televue and pentax xw is out of my price range I think and my current eyepieces are the ones that came with the telescope

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If you use a 4.7mm or a barlowed 8.8mm you will be getting 255x or 273x magnification. While you will be able to use these on the Saturn, mars the moon and double stars when the conditions are good, you might not find that those powers get as much "air time" as having wide angle eyepieces at lower magnifications / longer focal lengths ?

A very popular focal length for a first quality wide angle eyepiece is in the 12mm - 14mm range where it will probably deliver better value for money in your dobsonian ?

If you are on a tight budget I guess you want something that will get lots of use and justify the expenditure :smiley:

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Regards a Barlow:

A Barlow increases the magnification of the view in the eyepiece, this is what is widely known. But one should also bear in mind that it also magnifies any imperfection in the eyepiece and in the Barlow itself! And this is why I recommend the best Barlow one can find. I use TeleVue® 2X and 3X ones. Other people have other favorites that are also top-end.

I rarely recommend TeleVue® due to it's higher costs - which many can't afford - but I make an exception with Barlows. Even if it means saving-up for awhile before ordering one. But good news - the TeleVue® Barlow's aren't that much more expensive than middle-quality choices.

That's my story - and I'm stickin' to it!

Dave :p

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2 hours ago, John said:

If you use a 4.7mm or a barlowed 8.8mm you will be getting 255x or 273x magnification. While you will be able to use these on the Saturn, mars the moon and double stars when the conditions are good, you might not find that those powers get as much "air time" as having wide angle eyepieces at lower magnifications / longer focal lengths ?

A very popular focal length for a first quality wide angle eyepiece is in the 12mm - 14mm range where it will probably deliver better value for money in your dobsonian ?

If you are on a tight budget I guess you want something that will get lots of use and justify the expenditure :smiley:

thanks again for the advice, I read this page, http://www.astrosurf.com/luxorion/reports-epsuggestions.htm, yesterday and it suggest an 8mm, 20mm, 25mm and 30mm with a 2x barlow to cover, 4, 10, 12.5, 15, 20, 25 and 30, so I had a goal to get the 8.8, 2x and either of the 20 or 25 by the end of April (birthdays in march so might get some birthday money:icon_biggrin:) and then wait until the following autum. My worry with getting something 12-14 is that it becomes redundant later on, do you think it will still be used? Or maybe switch it for one of the list? Also, whilst I was looking at William optics and sky-watcher nirvana, I saw the sky-watcher myriad 9mm 100 degree AFOV, what are your thoughts on this compared to the ES 8.8

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1 hour ago, Dave In Vermont said:

Regards a Barlow:

A Barlow increases the magnification of the view in the eyepiece, this is what is widely known. But one should also bear in mind that it also magnifies any imperfection in the eyepiece and in the Barlow itself! And this is why I recommend the best Barlow one can find. I use TeleVue® 2X and 3X ones. Other people have other favorites that are also top-end.

I rarely recommend TeleVue® due to it's higher costs - which many can't afford - but I make an exception with Barlows. Even if it means saving-up for awhile before ordering one. But good news - the TeleVue® Barlow's aren't that much more expensive than middle-quality choices.

That's my story - and I'm stickin' to it!

Dave :p

Yes I think I'd much rather save than buy twice, I'll have a look at the TeleVue 2x then, thanks Dave

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2 hours ago, Eren said:

thanks again for the advice, I read this page, http://www.astrosurf.com/luxorion/reports-epsuggestions.htm, yesterday and it suggest an 8mm, 20mm, 25mm and 30mm with a 2x barlow to cover, 4, 10, 12.5, 15, 20, 25 and 30, so I had a goal to get the 8.8, 2x and either of the 20 or 25 by the end of April (birthdays in march so might get some birthday money:icon_biggrin:) and then wait until the following autum. My worry with getting something 12-14 is that it becomes redundant later on, do you think it will still be used? Or maybe switch it for one of the list? Also, whilst I was looking at William optics and sky-watcher nirvana, I saw the sky-watcher myriad 9mm 100 degree AFOV, what are your thoughts on this compared to the ES 8.8

My advice is to go with a lowest power, widest field eyepiece.  This will be tough on a budget with an f/4.7 telescope to keep the exit pupil below 6-7mm.  Normally, a 30-31mm 82 degree eyepiece would suffice for this purpose.  The problem is finding a decent one for 150.  You'll want this eyepiece for locating and centering objects before progressing to higher powers.  It is also handy for observing large objects like the Pleiades.

Your second eyepiece should be a good mid-power yielding 75x-100x and a 2-4mm exit pupil.  This would equate to a 12-17mm eyepiece.  You'll use this one the most, so spend more on it than the others.

Your third eyepiece should be a high power eyepiece yielding around 200x and a 0.8-1.5mm exit pupil.  This would equate to a 5-7mm eyepiece.  I would recommend a positive/negative design with eye relief of at least 10mm.  Even folks who suffer from astigmatism in their vision won't see much of it at very small exit pupils, so glasses aren't a necessity at high powers as they can be at lower powers.

With those three starter eyepieces of sufficient quality, you'll have 95% of your observing needs covered.  If you stick with the hobby, you can add more focal lengths to fill in the gaps as needed.  Buy higher quality eyepieces on the used market and you'll generally always be able to get your money back if you decide to sell them in the future.  Cheap eyepieces can be all but impossible to sell on the used market.

Personally, I started with a low cost 38mm modified plossl, a 14mm Pentax XL, and a 5.2mm Pentax XL with my 8" dob.  I also had a 9mm Vixen LV previous to my first scope for other purposes.  I still have all of them nearly 20 years later.

 

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Louis' advice is excellent - as usual! I'll only add that please don't fall into the trap of regarding the acquisition of more "stuff" for astronomy as a race-to-the-bottom of one's bank-account. With eyepieces, for example, take your time and observe with what you have for awhile - before getting more. This approach will allow you time to find out what you like to observe the most first - and then you can make a better and more informed decision regards what to put on your shopping-list.

Hope this helps -

Dave

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I've got a 10" SW f4.7 Dob. The 24mm 82° ES works exceptionally well in this scope. The 30mm version was good but felt a bit 'on the limit'. I have not tried their shorter length offerings. 

It is very natural to want more magnification, but ........ 4.7mm would hardly get used due to uk sky conditions. 6mm will get far more use. I have 5 & 6mm in my so case. The 5mm waits for the exceptional nights only!

My minimalist case would look like this :

24mm 82°, 68° 17/16mm & 8mm and a 68/50° 6mm. I don't do barlows for night time observing.

Hope that this helps.

Paul

 

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7 hours ago, Eren said:

thanks again for the advice, I read this page, http://www.astrosurf.com/luxorion/reports-epsuggestions.htm, yesterday and it suggest an 8mm, 20mm, 25mm and 30mm with a 2x barlow to cover, 4, 10, 12.5, 15, 20, 25 and 30, so I had a goal to get the 8.8, 2x and either of the 20 or 25 by the end of April (birthdays in march so might get some birthday money:icon_biggrin:) and then wait until the following autum. My worry with getting something 12-14 is that it becomes redundant later on, do you think it will still be used? Or maybe switch it for one of the list? Also, whilst I was looking at William optics and sky-watcher nirvana, I saw the sky-watcher myriad 9mm 100 degree AFOV, what are your thoughts on this compared to the ES 8.8

I don't like the focal lengths suggested there. The 25 is too close to both the 20 and 30 and then with the barlow this translates to the 12.5 being too close to both 10 and 15. Then at the high end the 4-8mm gap is too big, not to mention that under UK skies with your scope a 4mm might never be of any use. Lastly, the mid range focal lengths, where I agree with @Louis D is probably where you want to spend a bit more, is only covered by barlowed eyepieces which could impact on transmission, which is possibly most important at those lengths.  Louis' suggestions based on exit pupil are much better IMO, although some of the calculated focal lengths don't look quite right (eyepiece focal length = exit pupil * telescope focal ratio). Personally, I would starting with an eyepiece in the 2-2.5mm exit pupil range (10-12mm eyepiece for your scope) and then expand from there making sure you keep gaps of at least 1.4x between eyepieces so that there is an appreciable brightness difference, except at high magnification (~200x) where the atmosphere starts getting in the way and you might want to expand the number of choices (or use a zoom for seamless adjustment).

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I tend to agree with the above view.

Not enough shorter focal lengths and too many in the medium to long range with that set from my experience. I often skip straight from my 21mm to my 8mm - both are 100 degree eyepieces though, which makes a difference.

I did a review of the Skywatcher Myriad eyepieces for the forum here:

 

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Ricochet's X1.4 rule works well from 8mm upwards. And, he is definitely right about not putting a 25mm between the 30 & 20mm's (I made that mistake).

As with most things, beware of apparent short cuts. They rarely deliver without compomise. Zooms do not perform as well as dedicated single length eyepieces in a fast scope unless you send £600+. Field of view and, to a lesser extent, image quality suffer. I have the Baader Zoom which works fine on my slower scope for travel and solar. But the compomise at f4.7 is unacceptable imho. Barlows throw the focal point further out, making eye placement tougher.  Even with premium eyepieces, you will notice some drop in quality.

Paul

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6 hours ago, Louis D said:

My advice is to go with a lowest power, widest field eyepiece.  This will be tough on a budget with an f/4.7 telescope to keep the exit pupil below 6-7mm.  Normally, a 30-31mm 82 degree eyepiece would suffice for this purpose.  The problem is finding a decent one for 150.  You'll want this eyepiece for locating and centering objects before progressing to higher powers.  It is also handy for observing large objects like the Pleiades.

Your second eyepiece should be a good mid-power yielding 75x-100x and a 2-4mm exit pupil.  This would equate to a 12-17mm eyepiece.  You'll use this one the most, so spend more on it than the others.

Your third eyepiece should be a high power eyepiece yielding around 200x and a 0.8-1.5mm exit pupil.  This would equate to a 5-7mm eyepiece.  I would recommend a positive/negative design with eye relief of at least 10mm.  Even folks who suffer from astigmatism in their vision won't see much of it at very small exit pupils, so glasses aren't a necessity at high powers as they can be at lower powers.

With those three starter eyepieces of sufficient quality, you'll have 95% of your observing needs covered.  If you stick with the hobby, you can add more focal lengths to fill in the gaps as needed.  Buy higher quality eyepieces on the used market and you'll generally always be able to get your money back if you decide to sell them in the future.  Cheap eyepieces can be all but impossible to sell on the used market.

Personally, I started with a low cost 38mm modified plossl, a 14mm Pentax XL, and a 5.2mm Pentax XL with my 8" dob.  I also had a 9mm Vixen LV previous to my first scope for other purposes.  I still have all of them nearly 20 years later.

 

thanks Louis, I think I'll save for a good mid-power firstly and build from there, the pentax xw 14 is a bit out of my price range, do you think it's worth spending some more time saving for it?

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