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Old 17-12-2020, 10:42 AM
a5tarman
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10 Inch GSO Dob eyepiece recommendations

Hi guys, I just bought myself a 10" GSO Dob that comes with a 9mm, 15mm, 25mm Plossls, and 30mm superview.


I live under bortle 5-6 area, where I will do most of my viewing, so I suspect planets and the moon will be my best subjects, and some star clusters, and bright nebulae. I'd like at least one really nice eyepiece in my collection, in the short term. Probably from the Televue range. What eyepiece would you guys recommend as a first upgrade? I'm tempted by the TV Delite range for planets. Or am I better off getting a 16 or 17mm TV Nagler along with a 2x or 3x Barlow? Or should I think bigger (FOV wise) and look at the Ethos range?


The other question I have, is a 2x Barlow overkill with this scope and current line up of Plossls?
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Old 17-12-2020, 11:50 AM
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dannat (Daniel)
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barlow is overkill if you continue using the plossl’ s, though you could use it with the 15mm for a 7.5mm equivalent for planets

in your scope try and work out the planetary magnification you can use most, eg 175x, then work back by halving this figure, 85x -1250/85 = 15mm dso eyepiece, then use your barlow for planets..then aim to get your good eyepiece around this focal length, combined with a good barlow so you are using it twice.

nb some eyepieces like the pentax xw 14 don’t work well in short reflectors as it’s distortion is aimed to complement that of a refractor. have you thought about a coma corrector?

do you need long eye relief for glasses? if you;re staring out i wouldn’t go for an ethos just yet - you could look at a 15mm luminos from celestron, or the 16mm nagler
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Old 17-12-2020, 12:11 PM
Startrek (Martin)
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My first visual scope was a GSO 10” dob , now I use a Skywatcher 12” Goto dob
I sold all my Plössl eye pieces, they were entry level and got me started but I have now built up a Televue collection over 4 years , spent a lot of money but worth every cent ....... I also suffer from and myopia and astigmatism ( 1.5 diopter) in my right eye and myopia in my viewing eye which is ok as you can adjust focus to correct it
My collection .......
I had a Delite 7mm and 15mm but sold them due to what I purchased later ....
Panoptic 24mm for DSO
Panoptic 27mm for DSO
Delos 4.5mm for moon and planetary
Delos 6mm for moon and planetary
Delos 10mm for moon and planetary
Delos 17.3mm for DSO
Ethos 4.7mm SX for moon and planetary ( Lunar views out of this world, it’s like orbiting the moon from 100km up !!!! )
Ethos 8mm for moon and planetary
Ethos 13mm for DSO
Ethos 21mm for DSO ( best eye piece in the world IMHO )
Apollo 11 commemorative eye piece for moon and planetary
Paracorr Type 2 coma corrector ( excellent )
Powermate 2 x
Powermate 2.5 x
Powermate 4 x
Powermate 5 x
All Powermate T ring Adapters
I generally use my Powermates for planetary imaging
Televue Dioptrx

I observe under Bortle 3 to 4 skies

I’ve used the Nagler 22mm but never owned one ( a superb DSO eye piece )

If you have budget constraints don’t think buying Delites ( lower cost eye pieces ) will satisfy your hunger for better views, try and hold off , save up and buy Panoptic, Delos , Ethos or Nagler ( you won’t be disappointed I can assure you )

Cheers
Martin
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Old 17-12-2020, 12:48 PM
astro744
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The Tele Vue 17mm Type 4 Nagler is a 2" eyepiece whereas the 16mm Type 5 Nagler is 1.25" and there is a big difference in weight and size with the 17 being the heavier and larger of the two.

I would not recommend the 17NT4 with Barlow just to get higher power since for this combination to work without compromise you would need a 2x Powermate and this adds more weight to the point where you may have balance issues if your altitude bearings are light and smooth in action. A Tele Vue Barlow would be a bit lighter but the Powermate has the advantage of allowing the eyepiece to perform exactly as it was designed, i.e. no extension of eye relief and no vignetting which is more of a problem when barlowing longer focal lengths or eyepieces with already long eye relief.

The 16mm could be used with a Barlow or Powermate but note Tele Vue only has 2.5x and 5x Powermates in the 1.25" size. You can of course use the 16NT5 in the 2" Powermate with an adaptor.

The 16NT5 or 17NT4 by themselves in your telescope would give you about 75x and a bit over a 1 deg. field which is nice (assuming f5). However it is a power for say large open clusters, eta Carina, Orion Nebula etc. Globular clusters such as Omega Centauri or 47 Tuc can do with a bit more power that say a 13mm eyepiece would give on your telescope. You mention Ethos so I will compare the 13E to the 16NT5 and the true field is almost identical since the field stop diameter is almost the same. You simply get the same true field at higher power and wider apparent field.

See https://www.televue.com/engine/TV3b_page.asp?id=214

The Ethos is a very fine eyepiece with excellent transmission but the 100 deg. field is not for everyone and I urge you to go to any (Covid safe) star parties and look through as many eyepieces as you can to see what YOU like best. When I looked through a 13E or 8E I found myself looking around too much giving me a bit of eye strain but if looking at the centre, the field stop simply got out of the way. My personal preference is for the 82 deg. Nagler field particularly in the Type 4 series. Note eye relief of the Type 4 Nager series is good for eyeglass wearers if this is important to you. The eye relief of the 16NT5 is fine (at least for me) for non eyeglass wearers because of the volcano top design.

I would still recommend getting the shorter focal length you desire in a single eyepiece with your choice of apparent field as there are many to choose from.
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Old 18-12-2020, 06:07 PM
a5tarman
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So I ended up skipping on the TeleVue for now. I've been reading good stuff about the Baader Morpheus range, and it was much cheaper, so I took the plunge and ordered the 12.5mm. Hopefully I didn't make a mistake, but I assume most people in this hobby do at some point. I'll see how I go with this one and if I like it I'm thinking of adding the 6.5 or 4.5mm version to my collection for some better Lunar and planetary views.
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Old 19-12-2020, 12:59 PM
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dannat (Daniel)
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morpheus is a great choice, look for a 1.6x barlow for planets, or buy the gso 2.0x & unscrew the bottom to give 1.6x, will b good for planets
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Old 21-12-2020, 02:51 PM
Renato1 (Renato)
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Your telescope has 1250mm focal length and is F/5.

I think a 5mm eyepiece delivering 250X would be good for planets many nights after it achieves thermal equilibrium, assuming people around you don't have their heaters going.

A 2X Barlow would be handy for your 9mm eyepiece giving 277X - but you might find it frustrating tracking at that power. Or you may find it okay.

The 12.5 Morpheus gives a 2.5mm exit pupil which would be good for galaxies and faint clusters. With a 2X Barlow, it gives 200X, which works for planets on more nights than a 5mm eyepiece, where higher power might be delivering mushy views because of the atmosphere.

Start at 200X, then bump up power progressively until one gets a lousy image, then step back. One can hold 400X on some nights of the year.

Your 25mm and 30mm eyepieces deliver 5 and 6mm exit pupils, which are very good for low power views at dark sites, but the background image may be annoyingly bright when viewing in a light polluted sky.

I tend to go for a 4mm exit pupil for low power in polluted skies, so would keep an eye out for a wide angle or ultra wide angle 20mm eyepiece in the classifieds.
Regards,
Renato
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Old 22-12-2020, 11:11 AM
a5tarman
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Thanks for the suggestions. I also ordered a Televue 2x barlow which I thought would go nicely with the 12.5mm morpheus. I was checking out the conjunction last night with the standard 9mm plossl. I was surprised by the detail, so I imagine getting 6.25mm with the morpheus will be a pleasure on planets and the moon.



I can tell you I can't wait for the morpheus and barlow to arrive. I can't stand the narrow FOV with the standard plossl eyepieces. Luckily the scope came with a 30mm GSP Superview eyepiece. 68 degree FOV makes a huge difference.
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