marktownley
Carpal Tunnel
Reged: 08/19/08
Posts: 2261
Loc: West Midlands, UK
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Hi folks,
I own a Coronado SM40 and to be honest love this lil' scope, my only bug with it - as no doubt with others out there, is that helical focusser that comes with it. It's kinda ok for visual with smaller eyepieces, but put anything of any substance in there and you can feel the thing grating, plus it's about as manouerable and sensitive as a oil tanker.
I've toyed with various ideas for replacing the focus and finally in the week came up with a solution:
I noticed Moonlite do a 2" to sct adapter http://www.focuser.com/cgi-bin/dman.cgi?page=productdetail&plugin=dstore.cgi&product=SCT-adapter , now I know from experience of taking off the stock helical on the SM40 the inside diameter of the ota is pretty close, give or take a millimetre the same size as a 2" eyepiece.
This got me thinking as I have a Moonlite focusser on my C8 and also on my 5" meade frac. I could mate the moonlite adapter to the ota of the SM40 and then screw on the SCT moonlite to the back of this.
Well, said adapter arrived today and here are the results :-
For the purpose of todays exercise the moonlite adapter is just sitting in the OTA with a compression fit - not physically safe for operations, but at work on monday I have more tools than at home and intend to get it bolted on.
My first impressions are that I suspect there will be too much back focus with this setup - in the absence of sun I can't test the theory... If this is the case the OTA has a black endpiece that is screwed onto the OTA, with a bit of torque this should come undone and get me to be able to focus. The only thing I don't want to do is alter the SM40 in any way permanently, then in the future if I decided to sell it there is not irreversible alterations to it.
Anyway, hope you like my little experiment. I'm sure it will have a few incarnations before I settle on a final version. As always comments and suggestions are always appreciated!
Best wishes, Mark 
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stephenramsden
Pooh-Bah
Reged: 08/17/07
Posts: 1324
Loc: Atlanta, GA--USA
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nice work. I did a similar setup with my SM90. you can see it in the equipment section of my site www.solarastrophotography.com
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Stephen W. Ramsden
Atlanta, GA--USA
NASA SOLAR SYSTEM AMBASSADOR
www.solarastrophotography.com
www.SolarScopeReviews.com
www.stephenramsden.com
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Don W
Postmaster
Reged: 05/19/03
Posts: 14621
Loc: Wisconsin, USA
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Nice job. I hate helical focusers except the ones on my old Meade and Celestron finders. With those I'm just making a quick adjustment once a night and not having to use them all the time.
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Don Wyman
Obsession 18" f/4.5 #1166
W/Argo Navis DSC and Torus Primary
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cuwohler
Carpal Tunnel
Reged: 10/24/08
Posts: 1984
Loc: N 53.1 E 10.0
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Hi Mark,
that looks very professional and I think it is when you use bolted connections.
I have a similar problem with my new Equinox 120/900. I have no idea how to connect the Orion Motorfocus onto the focuser nor how to remove the focus wheel.
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Cai-Uso
http://www.cuwohler.de/
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mbucky
professor emeritus
Reged: 10/21/07
Posts: 647
Loc: San Diego
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hi mark
i think your setup will work nicely. moonlite focusers are great. i hope the black fitting will loosen for you (set screws?), as im sure that backfocus will be affected
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Michael Buxton
Lunt 75F BF1200
Takahashi TSA 102
DMK 21AU04 CCD
Orion Atlas EQ
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pjr200
Carpal Tunnel
Reged: 08/29/07
Posts: 2406
Loc: Staffordshire, UK
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Great setup and modification Mark, I hope it reaches focus.
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Best regards
Paul Robertson
My Gallery
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marktownley
Carpal Tunnel
Reged: 08/19/08
Posts: 2261
Loc: West Midlands, UK
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Thanks guys! Sun is out today so will have a go and see if I can get focus - tbh I don't think it will till the black section of the OTA is removed though.
Anybody ever removed one of these 'black sections' from a Coronado SM.. before?
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vegasMike
professor emeritus
Reged: 05/24/04
Posts: 605
Loc: Las Vegas
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Interesting setup you have, looks like trouble Do you actually need 2 CW's with that rig or is that just my eyes being weird?
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Can't afford an APO but I used to get my mail at one...
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stets
Carpal Tunnel
Reged: 04/13/06
Posts: 2262
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very interesting ... good luck with your modification ... look forward to an update
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marktownley
Carpal Tunnel
Reged: 08/19/08
Posts: 2261
Loc: West Midlands, UK
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Quote:
Interesting setup you have, looks like trouble Do you actually need 2 CW's with that rig or is that just my eyes being weird?
There is 2 CW's on there, and tbh they're not needed with this setup. It's just me being lazy and not taking them off after i've had the C8 or AR5 on there...
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Solar B
scholastic sledgehammer
Reged: 02/28/07
Posts: 912
Loc: By Edinburgh , Scotland
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Hey Mark thats well Cool,love the colour scheme,im a Moonlite convert to,cracking set-up,way better than any Lunt 
Brian
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" Gentlemen only ever use Refractors "
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