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solarGain
super member
Reged: 07/18/09
Posts: 135
Loc: London & la Palma, Canary Is.
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Hi. Could someone confirm that the hershel wedge can easily mate with the back plate of the 102. What are fittings required to achieve this? John
added... A 2 inch wedge and a change to the focuser possibily are what I have in mind!
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Solar eclipse chaser: Madagascar 2001, Libya 2006 and booked for Easter Island 2010.
PST Original blue . Manfrotto head/tripod x2.
Denk PST corrector, 21's & Denk II Binoviewer, wow!
Denk Bino/lunt diagonal adaptor.
Lunt LS100THa/ B1800 (Pressure-tuned) w/ Feather touch focuser. Vixen GP2 motorised ,& Vixen pier.
added 07 24 2009
Edited by solarGain (10/17/09 03:23 PM)
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Don W
Postmaster
Reged: 05/19/03
Posts: 14617
Loc: Wisconsin, USA
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Most Herschel wedges just slide into the eyepiece holder. Nothing more complex than that.
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Don Wyman
Obsession 18" f/4.5 #1166
W/Argo Navis DSC and Torus Primary
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ragebot
Carpal Tunnel
Reged: 08/26/05
Posts: 1671
Loc: Tallahassee, FL, USA
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Quote:
Hi. Could someone confirm that the hershel wedge can easily mate with the back plate of the 102. What are fittings required to achieve this? John
added... A 2 inch wedge and a change to the focuser possibily are what I have in mind!
Historically the problem has not been fitting a wedge into the OTA, but reaching focus. I got a Baader 2in wedge (which is basically a diagonal with a grated mirror that knocks down the light intensity and in some cases some ND filters)and it would not reach focus with my ED80 or Meade AR5. The vendor suggested I cut a couple of inches off the back of the OTA to solve the problem.
Instead I returned the wedge and got an APM 1.25 wedge which had no problem reaching focus. There have been several threads about the Baader wedges not reaching focus with all OTAs; something the APM wedges do not seem to suffer from.
I can not answer your specific question; but would advise you to examine the return policy of the vendor you get your wedge from.
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Meade ETX 90, Meade AR5, Orion ED80, Atlas GT, 8 in Newt, Coronado DS SM40, Garrett 10.5X70, Sigma SD10, SD14, Canon 1D2, Xti, Nikon CP4500, C-14
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vegasMike
professor emeritus
Reged: 05/24/04
Posts: 605
Loc: Las Vegas
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The rear focuser size/thread on the particular telescope in question is 36.4mm which is standard for Vixen 1.25" focuser's of this vintage. If mating a 2" housing H.W, you will either need a "step ring" that goes from 1.25">2" or replace the focuser with a focuser with a 2" drawtube.
If using a "step ring" you will need to further consider vignetting and image circle size as well as possible focus issues, all of which are possible but not probable.
If changing to 2" focuser is in the budget, and you must use a 2" H.W and not a 1.25" version, might I suggest a smooth 2 spd focuser from one of the popular chinese importers such as this or a variation of such from your side of the pond.
FWIW, being an owner of this particular telescope [(which is for sale by the way) <-- Is that a shameless plug or do I get points for cross posting  ] with a 1.25" focuser I have never felt the need to upgrade to 2" focuser due to the longer focal ratio. The combination of image circle size, useable magnifications and resulting exit pupil, side-railed that thought after the first few nights out with it. Needless to say the telescope in question was made as a visual instrument and and Vixen engineered it such for 1.25" accessories for a reason.
With that said, there would be nothing wrong with using a 2" focuser and Wedge, however a 1.25" Wedge might prove more suitable for this particular application. Unless it would be cheaper to replace the focuser than to replace the Wedge ( I hear those are expensive ), then all bets are off - replace the focuser 
Edited by vegasMike (10/18/09 07:38 AM)
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