I want to expand the eyepiece range for a recently acquired used 8¡¨ f/10 Celestron-8 SCT. It came with 1.25¡¨ and 2¡¨ diagonals and two Parks eyepieces, 2¡¨ 32mm Erfle and 1.25¡¨ 20mm ¡§GS-5¡¨ 20mm. The 20mm is nice on all objects (moon, planets, DSO) at 100X, so I would like to build from that. The 32mm gives about 1„a FOV at 60x that just frames the double cluster, but not quite as wide as I like for sweeping or low-power DSO views. For starters, I added rubber eyecups (eye position takes getting used to for a former Newtonian user), an 2x Barlow to get the 20mm up to 10mm/200x, and a 2¡¨-1.25¡¨ adapter so I don¡¦t have to switch out visual backs and diagonals just to change eyepieces.
This forum has been very helpful! Apparently the nice Parks 20mm is a ¡§Masayuma¡¨ twin of the Orion Ultrascopics and an ¡¥Antares¡¦ eyepiece line, so I can look to those (less expensive) lines as well as Parks for roughly parfocal eyepieces to fill in magnifications, like a 15mm and a 25mm to use with or without the Barlow. (Are the Celestron Ultimas really twins too? I¡¦ve read that, but the barrels, focal lengths and FOV are just slightly different than the others listed).
1. Orthoscopic question. Will I be likely to notice a difference compared to a 7.5mm or 10mm Masayuma/Parks/Ultrascopic, if I use a UO ortho, or even a re-barreled spotter scope orthoscopic in the 7 to 12 mm range, to have one lunar/planetary eyepiece for maximum power (7mm plain or up to a 9-12mm ortho that could also be used with the 2x Barlow)?. That¡¦s a subjective question, but please share experience with the comparison.
2. 40mm Wide Angle Question. To go wider than the 32mm, I would consider 2¡¨ eyepiece options at three price ranges:
a. Under $100 (47mm Surplus Shed ¡¦60„a Erfle¡¦, Gary Russel ¡§36mm Russian wide angle¡¨)
b. About $100 (40mm Antares Erfle, or a UO Konig II 40mm, or ? up to about $150?),
c. Go for broke: Celestron Axiom 40mm, (and what else under $275 shipped?).
All of those would give about 1.2„a to 1.4„a FOV. For sweeping that¡¦s closer to what I enjoyed in the past with an f/5.6 reflector and Rini eyepiece with field stop removed for 1.5„a+ FOV. The 4mm or so exit pupil would be fine with me , and less eye relief is better for me than more. Has anyone used these wider 40mm-range eyepieces with an f/10 SCT?
Thanks!
This forum has been very helpful! Apparently the nice Parks 20mm is a ¡§Masayuma¡¨ twin of the Orion Ultrascopics and an ¡¥Antares¡¦ eyepiece line, so I can look to those (less expensive) lines as well as Parks for roughly parfocal eyepieces to fill in magnifications, like a 15mm and a 25mm to use with or without the Barlow. (Are the Celestron Ultimas really twins too? I¡¦ve read that, but the barrels, focal lengths and FOV are just slightly different than the others listed).
1. Orthoscopic question. Will I be likely to notice a difference compared to a 7.5mm or 10mm Masayuma/Parks/Ultrascopic, if I use a UO ortho, or even a re-barreled spotter scope orthoscopic in the 7 to 12 mm range, to have one lunar/planetary eyepiece for maximum power (7mm plain or up to a 9-12mm ortho that could also be used with the 2x Barlow)?. That¡¦s a subjective question, but please share experience with the comparison.
2. 40mm Wide Angle Question. To go wider than the 32mm, I would consider 2¡¨ eyepiece options at three price ranges:
a. Under $100 (47mm Surplus Shed ¡¦60„a Erfle¡¦, Gary Russel ¡§36mm Russian wide angle¡¨)
b. About $100 (40mm Antares Erfle, or a UO Konig II 40mm, or ? up to about $150?),
c. Go for broke: Celestron Axiom 40mm, (and what else under $275 shipped?).
All of those would give about 1.2„a to 1.4„a FOV. For sweeping that¡¦s closer to what I enjoyed in the past with an f/5.6 reflector and Rini eyepiece with field stop removed for 1.5„a+ FOV. The 4mm or so exit pupil would be fine with me , and less eye relief is better for me than more. Has anyone used these wider 40mm-range eyepieces with an f/10 SCT?
Thanks!
