Come join the friendliest, most engaging and inclusive astronomy forum geared for beginners and advanced telescope users, astrophotography devotees, plus check out our "Astro" goods vendors.
Come join the friendliest, most engaging and inclusive astronomy forum geared for beginners and advanced telescope users, astrophotography devotees, plus check out our "Astro" goods vendors.
I am awaiting delivery of a step-down adapter for my 2" eyepieces. It will allow me to use my 2" eyepieces in a 1.25" focuser. The 2" eyepieces I would like to use in my 8" f/7.5 Newt are my ES 20mm/100° and my ES 30mm/82°
My question is, will there be visible effects created by this adapter? If so, what might they be?
Thanks
PS. I have a 2" R&P focuser that I could install on my Newt, but I'm not ready to do major surgery on that scope, yet.
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac ∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO ∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5 ∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros. ∞ Mounts: iOptron CEM70AG, SW EQ6R, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000 ∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3 ∞ Binos: 10X50,11X70,15X70, 25X100 ∞ AP Gear: ZWO EAF and mini EFW and the Optolong L-eXteme filter ∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°
Searching the skies since 1966. "I never met a scope I didn't want to keep."
JayTee wrote: ↑Fri Mar 25, 2022 7:42 pm
Hi Andrey,
Did you use 1.25" as a new field stop of sorts to get those numbers?
I have used 27mm - max field stop for 1.25" EPs. I know it is not as simple as that since you will see the FOV gradually loosing brightness at the edge instead of sharp field stop.
You might also get some internal reflections from the eyepiece barrel and some UW eyepiece designs are negative eyepieces, the field stop is not in front of the front element. Use of an adaptor will force the eyepiece to sit high off the tube wall. You will need a high focal point above the focusser to be able to reach focus.
The only light loss IMO will be vignetting.
Joe
Amateur astronomer since 1978...................Web site :http://joe-cali.com/ Scopes: ATM 18" Dob, Vixen VC200L, ATM 6"f7, Stellarvue 102ED, Saxon ED80, WO M70 ED, Orion 102 Maksutov, ST80. Mounts: Takahashi EM-200, iOptron iEQ45, Push dobsonian with Nexus DSC, three homemade EQ's. Eyepieces: TV Naglers 31, 17, 12, 7; Denkmeier D21 & D14; Pentax XW10, XW5, Unitron 40mm Kellner, Meade Or 25,12 Cameras : Pentax K1, K5, K01, K10D / VIDEO CAMS : TacosBD, Lihmsec. Cam/guider/controllers: Lacerta MGEN 3, SW Synguider, Simulation Curriculum SkyFi 3+Sky safari Memberships Astronomical Association of Queensland; RASNZ Occultations Section; Single Exposure Milky Way Facebook Group (Moderator) (12k members), The Sky Searchers (moderator)