astrodon
Pooh-Bah
Reged: 04/07/05
Posts: 1347
Loc: Hillsboro, OR, USA
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Lawrence-
In the photo of the Paracorr with the tunable top you can see that setting 5 is the lowest, for in order to reach that setting the tunable top with the slot in it must descend in order for the set screw to reach that level.
Hope I helped to clear this up, I know it is hard to get just by looking at the image,
~Don
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Don Miller
Meade 16" f4.5 in a hot water heater tube!
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Lawrence Sayre
Post Laureate
Reged: 10/16/04
Posts: 3704
Loc: N.E. Ohio
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OK, I finally realize that my intuitive view of the 5 being higher in the picture than the 1 was all wet, and I now trust that 5 is the lowest and 1 is the highest setting. Obviously the slide lever has to go up for the tunable top to go down, and visa versa. Thank you Don and Don!!! With that to go on, I've re-worked my spreadsheet once again, and I'm attaching it right here. I'm also now willing to believe that the TeleVue website chart is using the taller adapter for its 1.25" eyepieces. Please kick the tires with this spreadsheet, and let me know if it gives correct tunable top settings across the board.
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My philosophy, in essence, is the concept of man as a moral being, with his own happiness as the moral purpose of his life, with productive achievement as his noblest activity, and reason as his only absolute.
Ayn Rand (in the appendix to 'Atlas Shrugged')
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 10960
Loc: Los Angeles
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Lawrence,
It worked for my 31 Nagler and my Type 6 Naglers.
It didn't work for the 17 Nagler, with a field stop to shoulder dimension of -0.03"
The spreadsheet erroneously gives a setting of 5 instead of 3.
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Don Pensack
12.5" Truss Dob, 5" Maksutov
Sustaining Lifetime IDA member, TeleVue junkie
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 10960
Loc: Los Angeles
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Lawrence,
I accidentally included the adapter height for a 2" eyepiece.
Doh! 
Your calculator works fine.
Don
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Don Pensack
12.5" Truss Dob, 5" Maksutov
Sustaining Lifetime IDA member, TeleVue junkie
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Lawrence Sayre
Post Laureate
Reged: 10/16/04
Posts: 3704
Loc: N.E. Ohio
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Thanks!!!
Whew, you had me worried there for a bit. I was beginning to wonder if I would ever get it right. A sanity tester for sure.
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My philosophy, in essence, is the concept of man as a moral being, with his own happiness as the moral purpose of his life, with productive achievement as his noblest activity, and reason as his only absolute.
Ayn Rand (in the appendix to 'Atlas Shrugged')
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Keith
Vendor
Reged: 05/14/05
Posts: 182
Loc: Costa Mesa, CA USA
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for the 30mm 1rpd, setting 3, works suprisingly well. When I later aquired the real deal 30mm widescan III, suprisingly, it wasnt as well correctable with the paracorr, possibly because it has a wider field stop. I kept both eyepieces. Since I also aquired a nice f10 OTA, I use the WSIII with it, and my most recently aquired 31mm nagler with the dob, with or without the paracorr. I have the older photo/visual model, and the vignetting bothers me, so I will likely add the visual model in the future, and keep the other for my 8"f4 for imaging.
my 2c in the 8.8 UWA discussion, I used it in the lowest setting (5) with the included 1.25 adapter in 1.25 mode, like suggested for the 9mm nagler and it worked very well. I dont think I tried it with the 14mm yet, which I aquired more recently.
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 10960
Loc: Los Angeles
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I went back and looked for my records:
14mm UWA (used as 2")--setting 1
8.8mm UWA (used as 2")--setting 5
The 31 Nagler would be better corrected at setting 6. The fact there is no setting 6 shows the Paracorr was designed long before the 31 Nagler. I find it "tolerable" with setting 5, however. 
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Don Pensack
12.5" Truss Dob, 5" Maksutov
Sustaining Lifetime IDA member, TeleVue junkie
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Zooball
journeyman
Reged: 02/05/07
Posts: 9
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Thanks Don,
You just saved me a lot of work. I have both of those EPs and a brand new Paracorr PCV-2000 still snug in the box waiting for dark skies.
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sixela
Postmaster
Reged: 12/23/04
Posts: 9499
Loc: Boechout, Belgium
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Quote:
I woke up early this morning and I've been attempting to make a spreadsheet to calculate the ideal Paracorr tunable top setting based solely upon the field stop location of the eyepiece, and although in its present state it appears to give correct answers for all of the 2" TeleVue eyepieces, it gives incorrect answers for all of the 1.25" TeleVue eyepieces.
Probably means you haven't accounted for the extra 9.6mm caused by the Paracorr 2"-1.25" adapter.
Edit: never mind - late to the party...
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400mm f/4.46 David Lukehurst truss Dobsonian on Tom Osypowski equatorial platform
Orion Starblast (114mm f/4 reflector, Alt/Az)
Edited by sixela (08/28/07 11:56 AM)
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bkushner
Carpal Tunnel
Reged: 11/26/06
Posts: 1721
Loc: Audubon New Jersey
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What about Ethos?
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Celestron C80ED/SLT Mount/CG-5GT/SkyScout
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 10960
Loc: Los Angeles
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The position of the Ethos' focal plane is only 0.02" different than the Type 6 Naglers. That means setting 4 would be correct--the Nagler Type 6s WITH the adapter, and the Ethos WITHOUT an adapter.
I don't believe you could get the Ethos close enough to the Paracorr lens if used with a 1-1/4" adapter.
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Don Pensack
12.5" Truss Dob, 5" Maksutov
Sustaining Lifetime IDA member, TeleVue junkie
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sixela
Postmaster
Reged: 12/23/04
Posts: 9499
Loc: Boechout, Belgium
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Can't. In 1.25" mode in a 2"-1.25" adapter, it doesn't insert with the 1.25" barrel completely seated in the adapter, because the 2" barrel contacts the adapter.
When used this way, the focal plane is much too far from a Paracorr lens, even with a zero-length adapter.
Ethos: 2" mode, top fully pulled out.
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400mm f/4.46 David Lukehurst truss Dobsonian on Tom Osypowski equatorial platform
Orion Starblast (114mm f/4 reflector, Alt/Az)
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 10960
Loc: Los Angeles
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It works fine in a TeleVue "High-Hat" 1-1/4" adapter, but, in general, the Ethos should be used as a 2" eyepiece in 2" focusers. And in the Paracorr too.
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Don Pensack
12.5" Truss Dob, 5" Maksutov
Sustaining Lifetime IDA member, TeleVue junkie
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Mr. Bill
Carpal Tunnel
Reged: 02/09/05
Posts: 2759
Loc: Just passing through.....
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Anybody know offhand what the settings for the 14, 10.5 and 7 mm Pentax XLs is?
I say "is" because they are all parfocal.
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10x50 Fujinon FMT-SX binos
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sixela
Postmaster
Reged: 12/23/04
Posts: 9499
Loc: Boechout, Belgium
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Quote:
It works fine in a TeleVue "High-Hat" 1-1/4" adapter,
That doesn't fix the issue either, because the reason it works is because the high-hat adds extra length.
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400mm f/4.46 David Lukehurst truss Dobsonian on Tom Osypowski equatorial platform
Orion Starblast (114mm f/4 reflector, Alt/Az)
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Mr. Bill
Carpal Tunnel
Reged: 02/09/05
Posts: 2759
Loc: Just passing through.....
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Quote:
It works fine in a TeleVue "High-Hat" 1-1/4" adapter, but, in general, the Ethos should be used as a 2" eyepiece in 2" focusers. And in the Paracorr too.
That's what TV's Ethos instruction sheet plainly says....
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10x50 Fujinon FMT-SX binos
15x70 AP binos + Paragon p-mount
Oberwerk 100BT 45 degree + Hercules fork mount
120mm f/5 Orion achromat + Moonlite focuser
140mm f/5.7 Vixen NeoAchro Petzvel refractor
150mm f/6.5 Antares achromat
150mm f/8 homemade achromat....EE Barnard MW Sweeper
8 inch newt with f/5 Swayze mirror
10 inch f/4.7 Orion newt + Paracorr
15 inch f/5 Discovery split tube
35mm Pan, 26mm Nagler, 17mm Nagler, 13mm Ethos, 8mm Ethos
Member IDA
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Starkler
professor emeritus
Reged: 11/04/05
Posts: 692
Loc: Australia, Melbourne
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Quote:
Anybody know offhand what the settings for the 14, 10.5 and 7 mm Pentax XLs is?
I say "is" because they are all parfocal.
The Pentaxs appear to perform best with the tunable top set to the highest setting (which requires the max amount of focuser in-travel). I had to cut 15mm from my truss poles to accommodate but its worth it 
I find the paracorr works wonderfully as a field flattener, nicely mitigating the often criticised field curvature in the 14 and 21mm pentaxs
A note of caution! A friend handed me an OIII filter to try on my 31nagler. Dont try it as it hits the paracorr lens
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Geoff
15" SDM truss dob | Vixen r130sf | GSO 10" dob
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 10960
Loc: Los Angeles
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Quote:
A note of caution! A friend handed me an OIII filter to try on my 31nagler. Dont try it as it hits the paracorr lens
Ouch.
Note: 2" filters should be threaded on the bottom of the Paracorr for safety's (and convenience's) sake.
And don't use 1-1/4" filters on the bottom of the dual 1-1/4"/2" eyepieces when used as 2" eyepieces either. The filter will hit the lens if a lower setting is used.
If you use a Paracorr, it is safer to use all 2" filters and thread them on the bottom of the Paracorr.
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Don Pensack
12.5" Truss Dob, 5" Maksutov
Sustaining Lifetime IDA member, TeleVue junkie
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Olivier Biot
Amused
Reged: 04/25/05
Posts: 14334
Loc: 51°N (Belgium)
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For that reason I'm designing a 2" filter wheel that goes right below the ParaCorr.
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Tal-200K (#199) with JMI NGF-Mini2M focuser on GEM3 • Astro-Tech AT80ED on Orion Sirius EQ-G with EQDIR & home made wireless EQDIRECT • Celestron Regal LX 8x42 & 10x42 • Helios 15x70
ATM 14" f/5 (designing mirror cell and filter wheel/focuser) • ATM 10" f/6 Portable Truss (polishing) • ATM 10" f/25 Dall-Kirkham (primary: polishing, secondary: #120 grit)
AstroForecast
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Shawn H
Pooh-Bah
Reged: 05/16/07
Posts: 1132
Loc: Southern France 43°56'N-4°50'E
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Lumicon sells thier coma correcter for about 100 euros less than TV's paracorr in France, I'd love to hear if anyone has done a side by side comparison!
Shawn Haggerty Avignon, France
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