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The Warthog

Eyepieces - the very least you need.

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Very interesting read this.

I have a 10" Dob and it was supplied with two eyepieces:-

Super Plossl 25mm 52deg

Super Plossl 10mm 52deg

The supplier of my scope is also sending something he terms as a 'high powered' eyepiece.

Should I be thinking about any others at this early stage?

Stupid question but should I be looking at the 'Barlow' lenses?

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Very interesting read this.

I have a 10" Dob and it was supplied with two eyepieces:-

Super Plossl 25mm 52deg

Super Plossl 10mm 52deg

The supplier of my scope is also sending something he terms as a 'high powered' eyepiece.

Should I be thinking about any others at this early stage?

Stupid question but should I be looking at the 'Barlow' lenses?

If you are getting something like a 5mm (high power) EP from your supplier, I would not bother with a Barlow. I only use my Meade TeleXtenders (similar to Barlow in use, but different construction) for planetary imaging, simply because I have enough high power EPs anyway. In your case, I would consider a wide angle EP, to extend the field of view, but not after I had enjoyed the view with your current set-up, and got to know the scope better.

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I agree that eyepieces can run away with the budget, sometimes even costing collectively more than the scope itself! However, if you can afford to be patient, or ask around a really hands-on AS Group, it is possible to pick up a good quality e/p such as a Meade 5000 or Williams Optics quite reasonably. I have found the quality so much superior to the ordinary generic Plossl !

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hey,

very good post helped me out a lot. I just got a skywatcher skyliner 150p dobsonian and I've only got a 20mm plossel. thanks,

kelly :)

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Excellent original post and thread!

There's little I can add but to share what eyepieces I actually use after more than a decade of total immersion in the study of astro equipment. Put simply, the few eyepieces that I can't do without are those that produce exit pupils of 5mm, 2mm, and 1mm, regardless of scope. Of those, whichever eyepiece produces an exit pupil of ~2mm is going to see the most use. And if I were young again, I'd want an eyepiece that yields an exit pupil of as much as 7mm.

Few of us possess eyes with no inherent aberrations and large exit pupils tend to exaggerate aberrations of the eye - especially astigmatism. Similarly, many of us suffer to some extent from eye floaters and small exit pupils tend to floresce the things to the point of distraction. As do many, I therefore find the most comfortable range being exit pupils of 1 to 4mm in diameter, with 2mm being the most common sweet spot.

The premium wide-field eyepieces are fantastic and well worth the rather significant investment, but a well constructed Plossl is competent and forgiving, especially at focal ratios of f/6 and greater. Having tasted the ultra-wide experience, I'd find it hard to go back to a 50-degree AFOV, but when teasing fine detail from all but the most extended objects, few designs significantly exceed the image fidelity produced by a Plossl with lens elements of highest polish and premium coatings.

But regardless of eyepiece brand or design, 3 eyepieces and a 1.5x Barlow are generally all that I actually use during any given night and it's a rare night that finds me choosing one that produces an exit pupil smaller than 1mm with whatever scope is at hand. If I need more magnification, I just have to move to a scope of sufficient aperture to produce that magnification with an exit pupil of greater than 1mm. Your age-affected eye-pupil diameter, degree of eye astigmatism, and eye-floater count will vary, but you're still likely to find that an exit pupil of ~2mm is most comfortable for general viewing.

Hope this helps.

Gary

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Do bigger and/or better scopes take 2" EPs rather than 1.25" EPs? If so, maybe I shouldn't spend much on 1.25" EPs because I'll regret it when I upgrade. I bet it's not so simple, but I just don't understand why there's a difference so can anyone advise me please (in laymans terms)?

Are 2" EPs better than 1.25" EPs and why?

Thanks!

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There is no inherent difference except that 2" allows for a wider field of view: that's the benefit. The downside is higher cost (also 2" filters etc cost more than 1.25"). I've been using 1.25" eyepieces for years and have never felt the need for 2" eyepieces.

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Thanks acey. Does that make a telescope that has 2" EPs more flexible (as presumably it can accept 1.25" EPs using an adaptor & there's no point in putting a 2" EP on a 1.25" scope)? What sort of scopes have these 2" EPs?

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Lots of scopes have 2" focusers, including some entry-level ones, and yes it's more flexible if you think you might want to use 2" EPs. But it's also a bigger hole that potentially lets in more stray light. I preferred the rack-and-pinion 1.25" focuser on my old Orion 8" to the low-profile 2" Crayford focuser on my 12" Flextube. You can't judge EPs and focusers simply by diameter, any more than you can judge a telescope by aperture alone.

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To summarize, for an f/8 scope, we suggest a kit consisting of 6, 10, 16 and 24mm. For an f/10 scope, 7.5, 12.5, 20 and 30mm. For an f/5 scope, 2x Barlow, 8, 18, and 25mm.

Warthog excellent post! I have a new Skywatcher Skyhawk 1145p which came with a 2x barlow 10mm and 25mm eps. In your post summary you recommend the 8, 18 and 25mm eps... are these plossls or am I right in thinking if it doesnt say it on the tin it ain't a plossl?

I have found a set of Meade MA 5 piece 25mm, 20mm, 17mm, 12mm, 6mm it says they are three element eps... what do you think?

Oh nooooooooooooo I have just read that it might not be good to use a plossl with a scope of f5!

Edited by Patbloke

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MA is short for modified achromat. This have false color and reflections problems and are usually worst then even the cheapest plossls.

Sent from my X10i using Tapatalk

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Have seen a couple of S/H EP's for sale, apparently they came with a new skywatcher dob scope.

Are these lenses any good?

I presume they are better than the ones I have, marked H and SR.

Any rough guesses on how much these are worth?

Text on EPS is 'super 10mm' and 'super 25mm' .

Thanks.

Edit. my question is related to the one posted by Patbloke.

Will the unbranded 10mm and 25mm be better?

Edited by JohnDenim

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They are pretty poor too. Worth a fiver each at a stretch (and that includes delivery paid for by the seller) but most folks just ditch the 10mm. I sold mine with a diagonal and barlow for £12 the lot including delivery.

Edited by russ

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Thanks for the quick reply Russ.

There are these two on ebay.

10mm & 25mm eyepieces on eBay (end time 20-Jan-11 21:58:10 GMT)

Hope it's okay to post links here?

Anyway, from what you have said, I think you have saved me at the very least, £22.50.

If anyone wants to sell (to a very eager, if stupid, new Astonomer, i.e me! ) any EP's for a good price, please PM me. Thanks!

Edited by JohnDenim

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IF YOU HAVE A FAST SCOPE, say, f/5, this formula will suggest a 3.75mm or 4mm eyepiece. Looking through a Plossl at this length is a miserable experience. If this is the case, I would suggest you buy an eyepiece with a length equal to 1½ times your focal ratio, and buy a 2x Barlow lens in the same price range as your eps. These purchases give you your high power and medium-high power magnifications, so skip the next paragraph.

I got a Meade etx80 for Christmas as my first telescope. It came with the standard Super Plössl eyepieces (SP9.7mm, SP26mm). As I'm still getting used to it I probably don't need to buy anything else just yet (except the camera which is on its way!) but what would be the next lens? Reading the info above it would be a 7.5mm and a 2x Barlow. Unless I've misunderstood, the 9.7 gives me 41x magnification. Would it make most sense to add a 2x Barlow as my next investment?

Just to clarify my ignorance I still haven't mastered the telescope so know that there is a mirror change dial to increase magnification but not sure what it changes (ie how it affects the magnification). According to the Meade site it says that the Maximum Practical Visual Power is x275 and I seem a long way off this at the moment if my calculations are correct (even if I add a x2 Barlow).

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I have a 66mm quality refractor and I find X97 reasonable for jupiter although saturn could bear more magnification as it's image is a bit too small, so your ETX80 F5 (500mm focal length & has high quality optics I believe) could probably do with a 2X barlow and a 6mm eyepiece to give you 133X which should be fine for planets and double stars. X275 is WAY over the top for that aperture TBH, even if the optics were perfect, the image would be very dim and fuzzy.

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Thanks. Already managed to see Jupiter and one band but excited about seeing it in more detail (and possibly seeing Saturn). I can see the start another expensive hobby!

If I buy them one at the time I assume the Barlow will add more than the 6mm or am I wrong?

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Tiredboy: Oh - just read the ETX80 has a built-in barlow so you shouldn't need to buy one just a 6mm (or thereabouts) eyepiece.

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Hi, thanks for this interesting thread. Having read through lots of different topics on this forum I didn't realise how much of a difference better quality EP's could make.

I've had my first telescope for over 3 years now, using it on and off. The only EP's I have used are the two that came with the scope, a 10mm and a 17mm. The type of scope I have is a Konus 500, f4.3 with an Aperture of 114mm and a focal length of 500mm.

Which EP's and Barlows etc would you recommend to get the best out of my scope? I am quite excited by the idea of buying some good quality EP's and a barlow to see the improvement from the ones supplied. I am interested in viewing DSO's, Planets and everything else to be honest! Also keeping in mind I could use these EP's if I decide to upgrade my scope in the future.

Thanks

IXTL

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these days, just a 32mm plossl and 24-8mm zoom (barlowed when skies permit)

can cover my bases on scopes ranging from 90mm to 14".

the convenience of a premium zoom ep can spoil you fast.

they ain't naglers, but they ain't bad.

binoculars from 8x to 30x take care of my widefield cravings.

cheers

saber does the stars at

www.astronomyblogs.com/member/saberscorpx

Edited by saberscorpx

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So, to get a slightly larger view of Jupiter, I would need a 2x barlow and to complement my range a 18mm EP...At the moment I have a 9mm and 25mm EP that came along with my scope....

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So, to get a slightly larger view of Jupiter, I would need a 2x barlow and to complement my range a 18mm EP...At the moment I have a 9mm and 25mm EP that came along with my scope....

Yes, the 2x barlow would turn the 9mm into an effective 4.5mm.

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