John Huntley
super member
Reged: 07/16/06
Posts: 148
Loc: South West England
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My current eyepiece range is:
Nagler T5 31mm
Panoptic 24mm
UWAN 16mm
Nagler T6 13mm, 9mm, 7mm and 5mm
2.5x Powermate
These are used with my F/6.5 refractor and F/5.9 dobsonian scopes.
I've been offered a T5 Nagler 20mm but I would need to part with the 24mm Panoptic to fund it. If I did that it seems to me that I could also part with the UWAN 16mm as the step between 20mm and 13mm does not seem too much.
Can anybody see any benefits or drawbacks relating to this move that I should also consider ?.
Thanks
John
SW England
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Vixen ED102SS F/6.5 Refractor
Skywatcher 203mm F/5.9 Dobsonian
Vixen Portamount
Naglers: 31mm T5, 22mm T4, 13mm, 9mm, 7mm and 5mm T6's
Powermate 2.5x
Revelation 2.0" Dielectric Diagonal
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walt r
Carpal Tunnel
Reged: 02/13/07
Posts: 2421
Loc: Doylestown, PA
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The N20T5 is a very fine EP and would have a slightly smaller exit pupil than the P24 that would darken the background a bit more. The TFOV would also be slightly wider. If you don't need the extra eye relief then the N20 would be the better EP.
I had an N20T5 and the views were excellent but I needed more eye relief to use a Dioptrx to correct my astigmatism.
Check TV EP calculator .
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Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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Ben Ritchie
Lost in Space
Reged: 01/31/05
Posts: 4339
Loc: Bosham, UK
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I'd certainly go for it.
I found the 12 - 20 - 31 Nagler progression excellent and never missed having something between the 12 and 20 so doubt you'd miss the 16mm UWAN. The 20mm T5 is probably my favourite of all the Naglers, and the only slight negative is the limited eye relief (which I'd guess wouldn't be an issue for you, as you have T6s). The only possible issue I can think of is that both the 24mm Pan and 16mm UWAN would work with your Powermate (I think ... the 16mm UWAN is 1.25", right?) whereas the 20mm T5 wouldn't. You might possibly find yourself missing out on some permutation that you like with the Powermate, but, to me, that's the only negative I can think of. The 20T5's great!
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Astro-Physics 130EDT StarFire, 80ED (x2), 305mm f/5 dob, VLT
Astro-Physics 1200GTO, evolved HEQ5/pro
Coronado SM60/BF10, 3-6 Nagler zoom, 8 & 13 Ethos, 28UWAN
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j3ffr0
sage
Reged: 07/06/08
Posts: 238
Loc: Virginia
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Having to pop out the 1 1/4" adapter in and out of the focuser every time you swith between another EP and the 20mm might get tiresome. Worse still if you tried to insert a T6 without remembering to put the adapter back in. Yikes! 
Personally, I wouldn't be likely to make the move unless I was replacing the T6s with other EPs that have 2" barrels. I also own the 24mm Pan a couple type 6s and a 35mm Pan.
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10" Dob
127mm Mak
PST
35, 24 Panoptic; 16, 13, 9 Nagler
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Albie
Post Laureate
Reged: 02/22/05
Posts: 3521
Loc: Alberta,Canada
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You have six 82° ep's and one 68° ep.I personally would swap out the 24mm pan for the 20T5 nagler just for continuity and get rid of the uwan because imo it's too close to the 13T6.Going from 1.25" to 2" ep's isn't a problem for me.I've yet to drop an ep through the focuser.Rarely do I jump back and forth from 2" to 1.25",I usually settle into either high power viewing or low power viewing but not both and the transition from one to another is easy and painless
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Skywatcher 10" f/4.7 Dob with Moonlight CR1
Televue 2x barlow and 5T6,7T6,9T6,16T5 and 26T5 Televue Naglers.
SkyMaster 15x70,Regal LX 8x42 and Noble 10x28
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eddie kirkland
sage
Reged: 08/12/04
Posts: 446
Loc: Alabama
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I also have a 13T6 and 20T5 and love them both; I don't have a need for any in-betweens. You just need to get rid of the 4.8, 7, and 9 Naglers and purchase Pentax XW's.  
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Eddie Kirkland
Auburn, AL
16" f/4.5 Midnightelescope truss dob
10" f/6 Astrosky truss dob
Stellarvue/TMB 105
Stellarvue Nighthawk II
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nkoiza
sage
Reged: 12/17/04
Posts: 211
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Quote:
I also have a 13T6 and 20T5 and love them both; I don't have a need for any in-betweens. You just need to get rid of the 4.8, 7, and 9 Naglers and purchase Pentax XW's.
I agree with Eddie.
I have no need of anything between 31T5, 20T5 and 13T6, and the XWs (10, 7 and 5) work great thereafter.
Nick
16-inch f/4.4 David Lukehurst Dobsonian on Brian Reed Tracking Platform
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Lamb0
professor emeritus
Reged: 07/25/07
Posts: 668
Loc: Fairbury, Nebraska
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 I own both, and the 20T5 is a keeper. The 24 Pan delivers too good a view for me to sell, so I bought a cheap refractor I can only use my 1.25" eyepieces with instead! 
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John "Have eyepiece - will travel!"
8" f/5 Dob w/2.14" sec in a 12" alum tube 'The Mortar' - w/PCorr 2° TFoV @ 36.5X ~70% illum *NICE*
Typical eyepieces: 32 Burg, 24 Pan, 20T5, 5-8 SW, Others ALL 2": Pcorr, 2X PwrMt, Ast H-b, Lum UHC + OIII
60mm $50 Walmart Special in training - aka "Backpack Observatory"
Minolta Activa 12x50 , Steiner 15X80
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kfred
Carpal Tunnel
Reged: 11/11/03
Posts: 2005
Loc: Dayton, Ohio
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Hard decision because they are two great EP's. If you don't need alot of eye relief, then go for the 20T5.
Fred
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River Cam - Cambridge England
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Dan McC
member
Reged: 11/11/06
Posts: 52
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The 20mm would give a darker field of view and about the same true field; so you would see more.
Dan McConaughy
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KWB
Postmaster
Reged: 09/30/06
Posts: 7635
Loc: Westminster,Co Elev.1646Meters
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I like your thoughts,John. I've owned the Panoptic and as good as it is optically,I think the T5 had a tad more contrast. I don't think you lose much of any usefullness by stepping up from 20 to 31mm or stepping down from 20 to 13mm. You would still have a killer eyepiece collection.
I assume you don't have to wear glasses?
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Kenny
"When dealing with a mystery,choose the most unlikely of the likely possibilities"-Sherlock Holmes
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jtpowers1972
Professor or something
Reged: 11/03/05
Posts: 821
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Sell the 24Pan and the 16UWAN to get the 20T5. It's an excellent EP. The 16/20T5's are my all time favorites.
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John Huntley
super member
Reged: 07/16/06
Posts: 148
Loc: South West England
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Quote:
I assume you don't have to wear glasses?
No, I don't wear glasses to observe Kenny.
Thanks very much for all the input folks,
So far, the balance of advice is in favour of making the change from the 24 Pan / 16 UWAN combination to the 20mm T5 Nagler.
As I have some light pollution issues to deal with, the darker background sky that the 20mm T5 would deliver is valuable.
I am going to take some more time to think things through though - I don't want to be desparately seeking a 24mm Pan in a months time ....
Regards,
John
SW England
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Vixen ED102SS F/6.5 Refractor
Skywatcher 203mm F/5.9 Dobsonian
Vixen Portamount
Naglers: 31mm T5, 22mm T4, 13mm, 9mm, 7mm and 5mm T6's
Powermate 2.5x
Revelation 2.0" Dielectric Diagonal
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Biff
Carpal Tunnel
Reged: 09/04/05
Posts: 2254
Loc: Courtice, Ontario
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It all makes sense but you might want to hang on to the 24Pan. The 20T5 I'm sure is superior in every respect (I love mine) but the 24Pan could come in handy later on for 1.25" limited scopes if you foresee that need. I'd like to get a 24Pan at some point for this reason.
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Ryan
Antares 200mm f/6 Dob & 130mm f/5 Travel Dob.
Projects on the go...
- a couple 80mm SS refractors on the back burner.
- a few small mirrors awaiting polishing
- 260mm f/7.15 mirror... still polishing
Member of DRAA
 My house.
 DRAACO
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Lamb0
professor emeritus
Reged: 07/25/07
Posts: 668
Loc: Fairbury, Nebraska
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Quote:
The 20T5 I'm sure is superior in every respect
No, not quite, but it's very close. The 20T5 has a bit more lateral color, and pincushion. The 24Pan is my quality of field reference eyepiece in fast scopes as well as small/lightweight scopes with 1.25" adapters - it's that good!
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phanfave
Pooh-Bah
Reged: 08/21/06
Posts: 1268
Loc: Pioneer Valley
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If you can swing it keep both. You'll regret selling the 24 pan. Trust me I did.
Sean
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SV70ED, SV102ABV, C8, 10" Astro Sky
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IDA Member
Astro League At-Large Member
Planetary Society Member
Amherst Area Amateur Astronomer Association
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Lamb0
professor emeritus
Reged: 07/25/07
Posts: 668
Loc: Fairbury, Nebraska
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Um, my "Walmart Special" won't accept 2" eyepieces, this gives me another excuse to keep it. I need the 24Pan as my wide-field eyepiece - the included eyepieces are easily blown out of the water. Besides, I've enjoyed swapping eyepieces long before, (over 25 years), I owned a scope. $pending a lot of money on eyepieces isn't always worthwhile, but until you've seen what is available with the Mark I Eyeball, you can't know what you're missing. We all need to decide how good is "good enough" for ourselves. I'm also having an late 70s Edmund Scientific 20mm Kellner modified to be convertible for both 1.25" and .965" focusers. This will enable me to show the advantage of a ~$20 eyepiece in department store refractors - a 20K vs. 20H. I wouldn't want to scare neophytes into believing a $300 eyepiece is necessary! There is a reason I'm known in the Prairie Astronomy Club as "Have eyepiece - will travel!".
Clear skies,
John 
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John "Have eyepiece - will travel!"
8" f/5 Dob w/2.14" sec in a 12" alum tube 'The Mortar' - w/PCorr 2° TFoV @ 36.5X ~70% illum *NICE*
Typical eyepieces: 32 Burg, 24 Pan, 20T5, 5-8 SW, Others ALL 2": Pcorr, 2X PwrMt, Ast H-b, Lum UHC + OIII
60mm $50 Walmart Special in training - aka "Backpack Observatory"
Minolta Activa 12x50 , Steiner 15X80
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davidpitre
Pooh-Bah
Reged: 05/10/05
Posts: 1410
Loc: Central Texas
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How does the 22mm T4 compare to these two?
Big and heavy, yes. But otherwise?
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David
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BillP
Carpal Tunnel
Reged: 11/26/06
Posts: 2245
Loc: Vienna, VA
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If you are not adverse to switching between 2" and 1.25" eyepieces as you view, then I would trade out the 24 Pan but still keep the 16 UWAN. Reason? Because the 20T5 will exceed the TFOV your 24 Pan provides, but your 16 UWAN will still be very handy in your Dob as it will produce a better exit pupil (16mm=2.7, 20mm=3.4, 24mm=4.1).
If you often do not haul the 2" EPs with you and rely on 1.25"s then keeping the Pan would make sense.
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250mm f/4.7 Orion XT10i Dobsonian
102mm f/8.0 Tak TSA Super-APO
66mm f/5.9 WO ZenithStar SD APO
40mm f/10 Coronado P.S.T.
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Almach
Pooh-Bah
Reged: 02/27/07
Posts: 1184
Loc: Manitoba, Canada
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Quote:
If you can swing it keep both. You'll regret selling the 24 pan. Trust me I did.
Sean
I agree.
I have a 24 Pan (love it!!!) for 1-1/4" focuser useage.
The 20T5 is currently not in my arsenal and I don't really 'need' that particular EP ... but ... there is something about the T5 series that truly agrees with my eye.
One day ...
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Jim
Optical Star Fleet:
Orion XT10 f/4.7
Orion XT4.5 f/8
Orion 102mm f/7 ED
70mm f/7 Skywatcher Refractor
8x40 Nikon
Ocular Arsenal:
BO/TMB, Orion Sirius Plossl, Pentax, Televue
Ocular Support:
TV Paracorr, 2x & 2.5x Powermate, 2x TV Barlow, WO Binoviewer
Orion Skyview Mount
Observing since 25 December 2006
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