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gavbray
sage
Reged: 12/31/06
Posts: 232
Loc: Gold Coast, Australia
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I noticed Jon mentioned in a post (Collimation Fears Vanquished!) he has used his Mallincam to collimate his SCT.
Could Jon or anyone else who has had experience doing this explain the procedure?
Are you doing rough collimation using a very out of focus star or are you only slightly out of focus and viewing the diffraction rings?
If it's the diffraction rings, what settings do you use? I've never managed to see any rings.
Thanks
Gavin
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14" LX200R + SV90T + AP1200GTO
31mm, 22mm, 17mm Naglers, 13mm Ethos, 10mm Pentax XW, 2X Powermate, AP MaxBright
Mallincam Hyper Plus Color, DFG/1394 video converter, Optec 0.33 & 0.7 FRs
IDAS LPS, DGM NPB & OIII, Lumicon Deep Sky
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mielejr
sage
Reged: 05/29/05
Posts: 313
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Hi Gavin,
I use this method to collimate my C11. I defocus a 2nd-3rd mag star to where 3 or 4 diffraction rings are visible. I always see out of focus rings on brighter stars. I stand in front of the scope with the laptop screen turned towards me and adjust my collimation screws (Bob's Knobs) to acieve a concentric pattern. I also use the mount's hand control to recenter the star image after each adjustment. You must have the star centered in the FOV to properly evaluate the ring concentricity. I leave my mallincam on 2.1 sec at a low gain (3 or 4 from left). A faster integration time would probalby be better but I'm too lazy to open the menu and adjust the sense up settings. 
One thing you will notice is when your hand is in front of the corrector, all sorts of heat wave distrotions will show up. I have to wait a few seconds anyway for this to clear out.
The method works fine. It is basically the same as eyeballing through a high power EP but you just watch your video display instead.
John Miele
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Ruthenius
member
Reged: 11/15/06
Posts: 27
Loc: Gatineau, Quebec, CANADA
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Hi Gavin,
For rough collimation I use a very out-of-focus star, then to fine-tune it, I use a slightly de-focused star, with the Zoom on in the MallinCam.
Cheers!
Michael
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Michael F. Vasseur
Galaxy Blues Observatory
IAU Observatory Code H89
Gatineau, Quebec, CANADA
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Zoomster
professor emeritus
Reged: 01/30/05
Posts: 670
Loc: Tampa FL
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I have done this with my C11 and a SPC900NC webcam and my laptop. Works well for the first stage of collimation, although I did use eyeballs for final tweaking with a focused star.
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Celestron CPC 1100 aka "The Marino"
Moonlite Dual Rate Focuser
WO Dielecric Diagonal
Denkmeier "Big Easy" Binos and assorted eyepieces.
Coranado PST
SPC900NC...not modded...yet. (eh-eh)
Is God willing to prevent evil, but not able? Then he is not omnipotent. Is he able, but not willing? Then he is malevolent. Is he both able and willing? Then whence cometh evil? Is he neither able nor willing? Then why call him God?
Epicurus
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chupacabra
member
Reged: 03/26/07
Posts: 99
Loc: Land O'Lakes, FL
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I've also done the rough collimation using a webcam, but couldn't get any diffraction rings when in focus for really dialing it in.
Is this just a case of needing more effective focal length?
Could a Barlow be used to increase magnification and still produce an accurate diffraction pattern? I think I recall correctly seeing nice diffraction rings some time back when I had a 3x Barlow for doing planetary imaging and I stumbled on a nearby star.
Any input on this would be appreciated. It's easier for me to keep the orientations all straight when I'm not moving around. I'm not downright stupid, but for some stinkin' reason, I always get confusated when I am doing 180s between peeking in the EP and then tweaking the knobs.
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Kevin
Televue NP-127, TV-85, C9.25
Sirius EQ-G w/ ADM side-by-side hardware & Tau Ceti X-Y Finder (for guide camera)
QHY8 CCD camera, Canon 400D DSLR, Color Q Guider camera, ToUCam webcam
22mm Nagler, 13mm Ethos, 8mm Ethos, 5.9mm Siebert SS, 5mm SuperMonocentric
2x PowerMate, 3x PowerMate
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JAT Observatory
Space Freak
Reged: 02/20/05
Posts: 5662
Loc: Eastern PA
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I have used a webcam, the Meade LPI and a Mallincam with both a real star as well as an artificial star. I don't remember the settings I used but I just keep reducing the gain or shutter settings until the diffraction rings are visible. I can't remember the last time I used an eyepiece to collimate.
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-Marcus
The problem with free speech is even the stupid have a voice.
http://jatobservatory.org
12" LX200R on a Paramount ME
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Zoomster
professor emeritus
Reged: 01/30/05
Posts: 670
Loc: Tampa FL
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The barlow will work as well, I believe that is what I used. Just wait for a nice steady night and "get 'er done"!
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Celestron CPC 1100 aka "The Marino"
Moonlite Dual Rate Focuser
WO Dielecric Diagonal
Denkmeier "Big Easy" Binos and assorted eyepieces.
Coranado PST
SPC900NC...not modded...yet. (eh-eh)
Is God willing to prevent evil, but not able? Then he is not omnipotent. Is he able, but not willing? Then he is malevolent. Is he both able and willing? Then whence cometh evil? Is he neither able nor willing? Then why call him God?
Epicurus
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HendyPhoto
Sith Lord
Reged: 08/09/06
Posts: 1500
Loc: Bountiful, Utah
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I collimate with a speco and mallincam, and sometimes I throw on a 2X. As mentioned above, its great for the initial collimation, but I also use an eyepiece for final tweaking. I check it WAYYY extrafocal and intrafocal, then slightly de-focused (intra and extra), then focused with an EP. When I collimated my hyperstar I had to use the mallincam alone because you cant use an EP with hyperstar, but it gets me VERY close. Another way is to use a DSLR and keep shooting off expsoures with DSLR Focus or another similar shutter control program. That's how I will be doing a final tweak on the hyperstar collimation. Good luck, I am another one who thinks collimation is fun!
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~jon
SparkCast
CGE1400XLT w/HyperStar
90FD 66SD C6-R SN-8
CPC1100XLT Hutech 20D
Manny-Mod Vixen Porta
Mallincam MCHP
SPC900NC
CG-5 GT
"Two things are infinite: the universe and human stupidity;
and I'm not sure about the universe." --Albert Einstein
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mclewis1
Thread Killer
Reged: 02/25/06
Posts: 2456
Loc: Colorado
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Quote:
I am another one who thinks collimation is fun!
Jon, I always knew there was something "slightly bent" about you ... now I understand. 
I've also just started to use the Mallincam for checking collimation, I find that I can now sit down in a nice comfortable seat at the front of the scope and concentrate on manipulating the screws rather than having to reach around from the rear while looking into an eyepiece (and no jokes about knuckle dragging long arms or anything like that).
It takes a bit longer to setup the Mallincam/monitor for collimation but I find that the actual collimation takes less time and I'm a little less stressed doing it.
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Mark
C11, C6, APM/TMB115, and AT80ED
Tandem mount CGE and CG-5A, WO EZ-Touch, and AT Voyager
25x100s, 8x56s, T-Mount Light, and Mark 1 eyeballs
Modded 350D, DSI-P, SPC900, and Mallincam
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gavbray
sage
Reged: 12/31/06
Posts: 232
Loc: Gold Coast, Australia
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Thanks everyone for all the replies. I'll give it a go when I get a chance.
Regards
Gavin
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14" LX200R + SV90T + AP1200GTO
31mm, 22mm, 17mm Naglers, 13mm Ethos, 10mm Pentax XW, 2X Powermate, AP MaxBright
Mallincam Hyper Plus Color, DFG/1394 video converter, Optec 0.33 & 0.7 FRs
IDAS LPS, DGM NPB & OIII, Lumicon Deep Sky
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nytecam
Post Laureate
Reged: 08/20/05
Posts: 4823
Loc: London UK
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I find visual collimation virtually impossible nowerdays but I've done collimation as described via my CCD cams using USB2 download and suspect any imager with rapid refresh would suit 
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Nytecam 51N 0.1W
Meade 30cm LX200+ETX-70+DS-2090+C8+Ha+CaK PSTs SBIG SGS+homebuilt spectrographs
Starlight SXVF_M9/Lodestar/Canon 300D DSLR/Fuji E550
My observatory build-ETX-70 imaging-spectro page
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