Pentax XWs in fast refractors

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Bigzmey United States of America
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Pentax XWs in fast refractors

#1

Post by Bigzmey »


On forums many users are complaining about field curvature of 14mm and 20mm Pentax XWs. Well, I liked performance of 10mm XW so much that I decided to give them chance regardless.

To my surprise and delight I am getting very nice views with 14mm and 20mm XWs in my 150mm F5 achro. The FC is still there but you have to look for it and it is much less pronounced than with Meade 82 deg UWA 18mm and 14mm EPs.

It looks like in fact that XWs are correcting to some degree FC present in 150ST. Anyone observed similar effect in fast fracs?
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
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helicon United States of America
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Re: Pentax XWs in fast refractors

#2

Post by helicon »


I have yet to try the Pentax XW's. I'll keep them in mind for my next eyepiece purchase. Right now in my frac I'm using the GSO 30 mm Erfle and the ES line. 18mm works great.
-Michael
Refractors: ES AR152 f/6.5 Achromat on Twilight II, Celestron 102mm XLT f/9.8 on Celestron Heavy Duty Alt Az mount, KOWA 90mm spotting scope
Binoculars: Celestron SkyMaster 15x70, Bushnell 10x50
Eyepieces: Various, GSO Superview, 9mm Plossl, Celestron 25mm Plossl
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davesellars
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Re: Pentax XWs in fast refractors

#3

Post by davesellars »


Could be to do with the fact the design of the XWs was for spotting scopes? I only have the 5mm and 7mm and they perform excellently with my 120ST. I had a magnificent, sharp view of Jupiter with it and the 5mm XW a couple of nights ago.
SW Flextube 12" Dobsonian.
Starfield ED102 f/7; SW ED80; SW 120ST
EQ5 and AZ4 mounts
Eyepieces: TV Delos 17.3 & 10; Pentax XW 7 & 5; BCO 32,18,10; Fuyiyama Ortho 12.5; Vixen SLV 25.
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Bigzmey United States of America
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Re: Pentax XWs in fast refractors

#4

Post by Bigzmey »


davesellars wrote: Mon Jun 03, 2019 8:52 am Could be to do with the fact the design of the XWs was for spotting scopes? I only have the 5mm and 7mm and they perform excellently with my 120ST. I had a magnificent, sharp view of Jupiter with it and the 5mm XW a couple of nights ago.
Yes, this is most likely the reason. Just happy that it translates to refractors. :)

Last night I did more testing. This time with 50mm F4 Stellarvue finderscope. Initially, I used BST FlatField 19mm 65deg EP. This one gives ~6 deg AFV in the finder but the outer 20% of FOV had really bad FC. With XW20 I am getting ~7 deg AFV. There is some FC in the outer 10%, but it is milder and not distracting.

I got really nice wide field views of Milky Way clouds in Sagittarius with the finder and XW20. The only problem is that XW20 is now my most used EP in the scopes and I am not getting another one just for the finder. :lol: Delite 18.2mm also produced very nice but narrower views, so I may use it as the finder EP for now.
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
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davesellars
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Re: Pentax XWs in fast refractors

#5

Post by davesellars »


I'd imagine that the 20mm XW is a bit physically large as a finder EP anyway! Try to find a TV Panoptic 19mm to try out perhaps. Mine worked flawlessly with ther 120ST however f/4 is a bit more challenging. A cheaper option would be the ES68 20mm
SW Flextube 12" Dobsonian.
Starfield ED102 f/7; SW ED80; SW 120ST
EQ5 and AZ4 mounts
Eyepieces: TV Delos 17.3 & 10; Pentax XW 7 & 5; BCO 32,18,10; Fuyiyama Ortho 12.5; Vixen SLV 25.
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Bigzmey United States of America
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Re: Pentax XWs in fast refractors

#6

Post by Bigzmey »


davesellars wrote: Tue Jun 04, 2019 8:23 am I'd imagine that the 20mm XW is a bit physically large as a finder EP anyway! Try to find a TV Panoptic 19mm to try out perhaps. Mine worked flawlessly with ther 120ST however f/4 is a bit more challenging. A cheaper option would be the ES68 20mm
Yep, looks silly. I will snap a pic next time. I will figure it out. Plenty of EPs to try. With manual mount one spends as much time (if not more) looking through the finder as through the scopes. I am really enjoying this finder upgrade.
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
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Re: Pentax XWs in fast refractors

#7

Post by ab1963 »


I had a Stellarvue SVX102T-R F7 and had the 5,7,10,20 Xw's and were excellent in this particular scope , Sharp to the eof with nice contrast but the thing that stood out the most to me was the control of light scatter ,Fov didn't suit me but that's only a personal preference and can still remember a night viewing Mars with the 5mm and Imo the 5,7mm were the best of what i had
Tak FC100DF+FTF3035BA, Vixen SD81S+Baader D-Steeltrack
DM4, Berlebach uni 28
Baader BBHS mirror 2''
Powermate 2x
Nagler 31, Ethos 21, Delos 17.3, Nikon Nav HW 17/14, Docter 12.5,SV Optimus 4.7
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Lumicon oiii, uhc 1.25''-Dgm/Omega H-b 2''
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Re: Pentax XWs in fast refractors

#8

Post by Don Quixote »


Thank you Andrey.
The Pentax are very nice. Thank you for the comment on the twenty. In that range I have been tempted but I have a TV 22 Pan that I love so I have not gone the 20XW. I do covet the 5XW for the FOV and ER. In general the Pentax and the TV Pan are the most comfortable EP for my eyes. I am using the 14XW more lately as well. I am not sure I would notice the FC in the twenty. I can roll my eye from side to side in these XW and feel like I am looking out the porthole of the Space Station :-)
At this point I have run the XW in f6, f7.5, f9, f10, and I believe my 127 Mak f12 scopes. It serves in the frac and reflector equally well.
Clear skies Andrey.
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Re: Pentax XWs in fast refractors

#9

Post by j.gardavsky »


Hello all,

the Pentax SMC XW is an upgrade of the older Pentax SMC XL, both of them originally intended for the fast Pentax spotting scopes,
and especially for the Pentax APO spotters.
Otherwise, Pentax has been also designing and manufacturing the observatory grade refractors.

Best,
JG
6" F/5 Sky-Watcher achro, 2" BBHS Star Diagonal, 2" zenith prism, 1.25" Takahashi prism
Leica 82mm APO Televid
Eyepieces: Docter UWA; Leica B WW and WW Asph. Zoom; Leica HC Plan S and L, monocentric; Pentax SMC XW, O-, XO; Tak MC O, Carl Zeiss B WW, and Pl, E-Pl, S-Pl, W-Pl;
Swarovski SW; Baader Symmetric Diascope Edition; Nikon NAV SW, ; TMB supermonocentric; Rodenstock; Vixen HR; TV Delos
Filters: Astrodon, Astronomik, Baader, Balzers, Zeiss West and East, Lumicon
Binoculars (7x42 up to 15x85): Docter Nobilem, Leica Ultravid, Nikon Astroluxe, Swarovski EL Swarovision; BA8 (Kunming Optical)
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Re: Pentax XWs in fast refractors

#10

Post by Lady Fraktor »


When they do the limited release of the 30mm and 40mm XW this fall I will have to decide if I ill be purchasing them or not.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
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