Tom Polakis Tempe, AZ Visual observing, DSLR photography, lunar & planetary imaging http://www.pbase.com/polakis/
Quote:I am looking at the cheapie William Optics 1 1/4" binoviewer that sells with a pair of eyepieces. A support person at OPT told me that the added back focus is 4.5 inches, which means that it is unlikely to reach focus with my refractor. I understand that the provided Barlow doesn't do much to improve this situation. Has anybody tried different Barlows with better results for reducing the back focus problem? If so, can you estimate the added back focus? Thanks.Tom
Don "Don't worry about what telescope you own, or its quality. Just get out under the night sky and enjoy God's wondrous universe" Thomas Back.
ES 68º series complete 2x ES Barlow WO Bino's NPL 30 RKE 28 SWA 20 15 WA 12 pairs 150 f12 Istar Achro f4.8 Orion Optics (UK) VX 10" Newt NEQ6
Celestron Advanced VX Edge8; Celestron 20X80 binoculars on a 1st surface mirror mount; Orion Q70 set; WO Binoviewers; Nikon 16X50 binoculars.
A little girl once asked as I showed her the Moon with my telescope, "Are you a scientist?" No, it's just a hobby....
South of Seattle - east of Tacoma
Quote:Are you using a 2" diagonal?
United Optics 130 Triplet Refractor - SkyWatcher 102 F5 Refractor & SM90 / BF15 - Orion 120mm F5 Refractor & Baader Herschel Wedge - AZ -EQ6 GT mount & SkyWatcher Alt-Az mount - QSI 683 CCD & Grasshopper 3 2.8mp (674) - 3 Nikon cameras & 1 Canon - To many Nikon lenses - EP's 2 x ES 6.7's, - 2 x ES 8.8's, - 2 x ES 11's, - 2 x ES 16's - 2 x Denk 21's, - 2 x Brandon 24's, - 2 x RKE 28's - 1 x Nagler 12m, - 1 x ES 30 - Denk 27 Bino
Quote:I just put the b-viewers straight into the focuser drawtube on my refractors, and bypass any diagonal.I actually prefer not using a diagonal in my refractors.
My eyepieces are made from the waste product of exploding stars. 10XTi 102XLT ST80A(2" Focuser) XW: All; XO: 2.58 Televue: Naglers-T1 Smoothside-full set, 17T4,12T4,Ethos 17,4.7; plossels-40,32,20,17,&7.4mm; Pans-22,24mm; Delos-6,8,12,17.3mm ES100: 5.5,9*,14,20 ES82: full set ES68: 16,20,24,34 NLV: 5,9,10,15 Ortho: HD-7,9; OPS-9,12 Meade RG 7mm Other: Pentax 12.5K(.965), 10mm Parks Zoom: Nag3-6 *=on b/o DAS Dark Site
Quote:While not cheap, its not overly expensive either, Seibert Optics makes a diagonal for binoviewers that allows you to use the binoviewer without any barlows, screw on or otherwise.
C14 XLT, CGE NexSTAR 11 GPS + 120ST APM/TMB 130/780, AT111EDT SW EQ5P (2" Tripod/20" Pier) XW's 3.5mm - 20mm, 28mm RG, TVZ 2-4 ES14mm/20mm 100° UWAN 28mm,Paragon 40mm, TV55, Meade 2X 2" TeleXtender TMB SMC 4mm-16mm, Pentax 0-18, CZJ 0-25 EarthWin PFS-DBSE, WO DuraBright, AP MaxBright TV Bino's Bino Sets X 2: UO H.D's ~ 5mm-18mm, TV Pl.(NJ's)7.4mm - 40mm 16T5's, 24mm Pans Canon 18X50 IS Pentax 7X35 (9.3°