Brian Schmidt
sage
Reged: 01/25/09
Posts: 200
Loc: Roswell, GA
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Another vote for the 13 T6---congrats on that one! I used to use a 15mm Ultrascopic, which is a great eyepiece by the way, in my 8 inch dob. Earlier this year I got the 13 T6 and it really is my all around go to ep. It shows almost everything well, except for the larger opens. Even the planets look good in it, even though I usually use the 7 T6 for high power viewing.  Honestly, that is my most used ep.
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Brian
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Tiny
super member
Reged: 05/02/08
Posts: 193
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im in the process of comparing my naglers to ES 82*s and to be honest im not seeing much of a difference.
If you want to stick with naglers, more power to you. They're proven eyepieces and are fantastic. You also wont take a very large hit if you sell any second hand. However dont think that Naglers are the end all be all of wide fields.
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gtown1
member
Reged: 11/07/08
Posts: 65
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One eyepiece is not a good solution. You should have at least three--a low, a medium, and a high power eyepiece. You could start by purchasing a low and medium power eyepiece then add the high power one later.
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Happy owner of an Obsession, 18 inch Ultra Compact and a Mag 1, 12.5 inch Porta Ball.
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Pete Kopfer
member
Reged: 12/01/08
Posts: 84
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Quote:
...I have made my decision and the 13T6 will in fact be my first Nagler. I suspect from all I have read here on Cloudy Nights that I will be quite pleased with the purchase...
Not that you probably need more validation but I like your choice. I think you are really going to like this eyepiece in both of your telescopes. I'm always amazed at how small the 13mm really is, especially when you consider what an expansive (and sharp!) view it provides. My first TV too.
Pete
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JimmyK
super member
Reged: 03/24/07
Posts: 124
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Quote:
One eyepiece is not a good solution. You should have at least three--a low, a medium, and a high power eyepiece. You could start by purchasing a low and medium power eyepiece then add the high power one later.
xxx
Greetings,
Sorry if I left the impression this was my only EP. I am just not happy with what I have so far accumulated.
I have the following;
Burgess/TMB Planetary Series 2.5, 4, and 9.
Mead UAW 6.7
Orion Edge On Planetary 12.5
Orion Sirius Plossl 25
Mead Super Plossel 32
Agena Astro UWA 15 (2 inch)
Zhumell WF 26 (2 Inch)
GSO SuperView WF 30 (2 Inch)
Mead MA 25
Mead MH 9
Zhumell Plossel 9
Orion Sirius Plossel 10
Mead 2x Barlow and an unnamed 3x
Just looking to refine the views now. I can see there's more to see in what I'm seeing. 
Regards
JimmyK
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Z10" Dob
Orion 150mm Mak-Cas on a CG-5 Advanced Go To
25x70 Binos
"The heavens declare the glory of God;
the skies proclaim the work of his hands."
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starrancher
professor emeritus
Reged: 06/09/09
Posts: 585
Loc: Northern Arizona
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Cheeese ! All I have are Plossls !.................
Oh ! ...By the way , .....Did I mention that I love my Plossls ?!
I love all of my Plossls ! 
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LXD75 AR5
LXD75 SN8
Series 4000 Plossls
Misc. other stuff
Fort Rock , Az .
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j3ffr0
sage
Reged: 07/06/08
Posts: 422
Loc: Virginia
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Congrats on the 13T6; I'm sure you will love it. The 13T6 was my first Nagler too. It's remains one of my favorites (second only to the 16T5).
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10" Dob, 127mm Mak, 120mm f5 achro, PST
35, 24 Panoptic; 16, 13, 9, 3-6 Nagler
15, 10, 7.5, 5, 3.8 Ultrascopic
20, 15, 9, 6 Expanse
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PJF
professor emeritus
Reged: 05/06/04
Posts: 667
Loc: UK
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Quote:
...gives the 17T4 more of a widefield "spacewalk" experience than the 13T6, even though both are technically bona fide 82-deg AFOV EPs.
(emphasis added)
The 13T6 is not an 82-degree apparent field of view eyepiece: it doesn't even break out of the seventies. Whatever bona fide technical merits it has, an 82-degree AFOV isn’t amongst them.
Quite visually noticeable too...
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Peter
10x50 binocs
ED80 'frac
6" f/12 Maksutov
6" f/6 Newtonian alt/az
10" f/4.3 Newtonian alt/az
Bryce
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Albie
Post Laureate
Reged: 02/22/05
Posts: 3667
Loc: Alberta,Canada
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Quote:
The 13T6 is not an 82-degree apparent field of view eyepiece: it doesn't even break out of the seventies. Whatever bona fide technical merits it has, an 82-degree AFOV isn’t amongst them.
Quite visually noticeable too...
 
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Starblast6
Stratus 24mm,Speers Waler 4.9mm 7.2mm and 9.4mm
Noble 10x28,Regal LX 8x42,Skymaster 15x70
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astro744
member
Reged: 09/22/07
Posts: 70
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Quote:
Quote:
...gives the 17T4 more of a widefield "spacewalk" experience than the 13T6, even though both are technically bona fide 82-deg AFOV EPs.
(emphasis added)
The 13T6 is not an 82-degree apparent field of view eyepiece: it doesn't even break out of the seventies. Whatever bona fide technical merits it has, an 82-degree AFOV isn’t amongst them.
Quite visually noticeable too...
Yes. I have mentioned this a few times myself in previous posts. The numbers say it all as does visual comparison.
Here are the specs. of 3 Naglers:
13mm T6 field stop dia = 17.6mm
12mm T4 field stop dia = 17.1mm
11mm T6 field stop dia = 14.9mm
AFOV = fsd x 57.3/fl
13mm AFOV = 17.6 x 57.3/13 = 77.6 deg. (78)
12mm AFOV = 17.1 x 57.3/12 = 81.7 deg. (82)
11mm AFOV = 14.9 x 57.3/11 = 77.6 deg. (78)
The above calc does not take into acount any distortion.
Now to play with the numbers a bit more:
11/13 = 0.846
17.6 x 0.846 = 14.9
However, 11/12 = 0.917
17.1 x 0.917 = 15.7. The FSD of the 11mm should be 15.7mm.
15.7 x 57.3/11 = 81.8 deg (82)
13/12 = 1.08
17.1 x 1.08 = 18.5. The FSD of the 13mm should be 18.5mm
18.5 x 57.3/13 = 81.5 deg (82).
Visually through an 10" f6 Newt I could detect only the smallest increase in true field between the 12mm and 13mm Naglers. They were almost the same which means the 0.5mm difference in FSD is hardly noticeable which also means the AFOV cannot be the same.
Now after saying all of the above I do find the 12mm T4 a most pleasing eyepiece to use but also like the 13mm T6 for its compact size.
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KRS1
member
Reged: 02/02/09
Posts: 81
Loc: Anglesey, Wales, UK
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Heres a spanner in the works, if money is not a problem get a 13mm Ethos 
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Chris
Skywatcher Heritage 130p
Orion xt10i (on the way)
Some eyepieces & a barlow, I'm just starting out.
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Johndob
super member
Reged: 12/22/08
Posts: 146
Loc: Newport Beach,Ca
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xxx
Greetings,
Sorry if I left the impression this was my only EP. I am just not happy with what I have so far accumulated.
I have the following;
Burgess/TMB Planetary Series 2.5, 4, and 9.
Mead UAW 6.7
Orion Edge On Planetary 12.5
Orion Sirius Plossl 25
Mead Super Plossel 32
Agena Astro UWA 15 (2 inch)
Zhumell WF 26 (2 Inch)
GSO SuperView WF 30 (2 Inch)
Mead MA 25
Mead MH 9
Zhumell Plossel 9
Orion Sirius Plossel 10
Mead 2x Barlow and an unnamed 3x
Just looking to refine the views now. I can see there's more to see in what I'm seeing.
Regards
JimmyK
Keep us informed what you uncover with the 13t6 that you couldn't with your current EP'S. John
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Zhumell 10" Dob (Mods)
ETX-125PE UHTC
ETX-90AT
6"f/5 Newtonian
Classic 60x910
Ortho 6-7mm UO or.4mm
Meade 3000 5mm
Zhumell 2" ED Barlow
Zhumell 2" 32mm
UO. 2" 30mm 
GSO 2" 26mm
GSO 40mm CPL
Hyperion 8,13,17,21&FTR
Zhumell 8-24 Zoom
ED 3.8mm,7.5mm
Owl SP4,10,15
Zhumell EP&filter set 1"1/4
Baader 2" Neodymium/IR-cut,CelestronUHC/LPR
Zhumell OIII,UHC,SkyGlow,Polarizer
Zhumell 20x80 Giant&
10x50 plus 3 More Bino's
Brunton Echo Monocular
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JimmyK
super member
Reged: 03/24/07
Posts: 124
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Hi John,
First decent weekend in The Hill Country I will be doing some comparisons and reporting back. Any notable differences, in particular at like magnifications will be documented.
I am most interested in comparing the Orion Edge On Planetary 12.5 ( $105.95 ) to the 13T6 ( $275.00 ). I want to see if the slightly better than 2 x the $$ is justified.
The difference of $170.00 is a front tire on a Harley installed which is what I will be thinking about as I compare the two.
The 12.5 produces 100x in my DOB while the 13T6 should produce 96.15.
In the MAK/CAS it is 144x compared to 138.46x.
I think this should be close enough to determine the actual worth and if more rubber on the road or sparkle in the sky is the way to go next time.
Regards
JimmyK
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Z10" Dob
Orion 150mm Mak-Cas on a CG-5 Advanced Go To
25x70 Binos
"The heavens declare the glory of God;
the skies proclaim the work of his hands."
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helpwanted
Carpal Tunnel
Reged: 07/04/07
Posts: 2650
Loc: Phoenix, AZ
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while i love the SPL clones, it's not fair to compair it to a 13T6... that's the sharpest of all the T6s! ...i even don't like the T6 eyerelief!
let us know your thoughts!
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cuir
Pooh-Bah
Reged: 03/03/07
Posts: 1132
Loc: Up north.
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Good call on choosing the T6 13mm.
It is a fantastic FL for the 6" mak, bringing in a moderately high magnification that is almost always usable, even under the most miserable seeing conditions, and a nice, deep, yet low powered widefield for the 10" newton.
It will likely become "the" workhorse on the Mak.
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Seb
Eyepiece spreadsheet v6.8
Choosing the right eyepiece
Main scope: 150mm Maksutov
Scnd scope: 200mm Schmidt-Cassegrain
Favorite ep: 24 Panoptic and 11m T6 Nagler
Pref'ed filters: Lumicon 0III and UHC
Mounts: EQ6-Pro and Skyview AZ
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Scott Watson
sage
Reged: 05/26/06
Posts: 279
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Quote:
17T4 Nagler is the most versatile for a dob of your aperture/focal length, and has the bigger eye lens over the T6 line which gives the 17T4 more of a widefield "spacewalk" experience than the 13T6, even though both are technically bona fide 82-deg AFOV EPs. You can pick these u for around $300 (sometimes around $275) used, in good condition.
That said, the 13T6 would be my second-place nominee, a very solid choice in its own right.
NOTE: I have the 31T5, 26T5, 17T4, and five consecutive T6s from 13mm through 5mm inclusive. I think the 31T5 is the finest low-power widefield eyepiece in existence. But if I could pick only ONE among the whole bunch, it would be one of the two I nominated above, in the order indicated.
Indeed. I have seen one on the shop & swap for $275...
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cuir
Pooh-Bah
Reged: 03/03/07
Posts: 1132
Loc: Up north.
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The 17T4, most likely, cannot be used on his 6" Mak, which it probably a typical 1¼" part. Besides this, at 17mm of FL, this is going towards the widefield FLs, and the OP is clearly looking for a higher magnification eyepiece, and
I quote:
Quote:
... I am looking at either the 5mm, 7mm, 11mm, 13mm. I figured at $259 the price is not that bad...
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Seb
Eyepiece spreadsheet v6.8
Choosing the right eyepiece
Main scope: 150mm Maksutov
Scnd scope: 200mm Schmidt-Cassegrain
Favorite ep: 24 Panoptic and 11m T6 Nagler
Pref'ed filters: Lumicon 0III and UHC
Mounts: EQ6-Pro and Skyview AZ
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