guide scope

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Tylerbo
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guide scope

#1

Post by Tylerbo »


hey everyone, I'm looking to see if there is anything I can do with my guide scope. I keep getting halos around my stars I'm curious if I can do something i.e. either paint the inside black or something any suggestions.
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sdbodin United States of America
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Re: guide scope

#2

Post by sdbodin »


A bit more info is needed, is the guide scope a simple refractor? Is your guide camera a CCD or Cmos? If both are true, then put in an IR cut filter because the cameras are very sensitive to infrared and the scope will not focus these.

Just a guess,
Steve
Scopes; Meade 16 LX200, AT80LE, plus bunch just sitting around gathering dust
Cameras; Atik 460ex mono, Zwo ASI1600MC-cool, QHY5L-II color and mono
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Tylerbo
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Re: guide scope

#3

Post by Tylerbo »


I'm using a zwo 60mm guide scope with a 290 asi camera and a 120 asi mono camera
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sdbodin United States of America
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Re: guide scope

#4

Post by sdbodin »


Tylerbo wrote: Mon Sep 30, 2019 7:07 pm I'm using a zwo 60mm guide scope with a 290 asi camera and a 120 asi mono camera
Not a guess anymore.

Steve

P.S. But it shouldn't matter if you are guiding OK, guide programs look for the center of the star anyway.
Scopes; Meade 16 LX200, AT80LE, plus bunch just sitting around gathering dust
Cameras; Atik 460ex mono, Zwo ASI1600MC-cool, QHY5L-II color and mono
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Tylerbo
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Re: guide scope

#5

Post by Tylerbo »


well the star doesn't look good granted I have an AVX and ive never been able to get good guiding anyway
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bladekeeper
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Re: guide scope

#6

Post by bladekeeper »


Tylerbo wrote: Mon Sep 30, 2019 10:47 pm well the star doesn't look good granted I have an AVX and ive never been able to get good guiding anyway
You need to come over one evening and we can take a look at that. I tend to get pretty good guiding with my AVX, though I think I somehow got a good one...
Bryan
Scopes: Apertura AD12 f/5; Celestron C6-R f/8; ES AR127 f/6.4; Stellarvue SV102T f/7; iOptron MC90 f/13.3; Orion ST80A f/5; ES ED80 f/6; Celestron Premium 80 f/11.4; Celestron C80 f/11.4; Unitron Model 142 f/16; Meade NG60 f/10
Mounts: Celestron AVX; Bresser EXOS-2; ES Twilight I; ES Twilight II; iOptron Cube-G; AZ3/wood tripod; Vixen Polaris
Binoculars: Pentax PCF WP II 10×50, Bresser Corvette 10×50, Bresser Hunter 16×50 and 8×40, Garrett Gemini 12×60 LW, Gordon 10×50, Apogee 20×100

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Micke187 Sweden
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Re: guide scope

#7

Post by Micke187 »


If you get halos around your stars then the focus is way out. How far have you pushed in the camera into the guidetube? I think if you have the cam out more from the tube it will get esier to get focus.
TS-optics photoline 115mm triplet + 1.0x flattener
Guiding: qhy5lll APM 50mm guidescope
Main camera: ASI1600MM pro +Starlight xpress filterwheel (Ha,OIII, SII ,LRGB baader filter)
Mount: heq5 Rowan mod
Zwo EAF focuser
Programs: APT, DSS, PIxinsight, Nebulosity3, Phd2, CDC Eqmod
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Tylerbo
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Re: guide scope

#8

Post by Tylerbo »


Micke187 wrote: Tue Oct 01, 2019 6:03 am If you get halos around your stars then the focus is way out. How far have you pushed in the camera into the guidetube? I think if you have the cam out more from the tube it will get esier to get focus.
I got the camera all the way in unfortunately
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Tylerbo
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Re: guide scope

#9

Post by Tylerbo »


bladekeeper wrote: Tue Oct 01, 2019 5:02 am
Tylerbo wrote: Mon Sep 30, 2019 10:47 pm well the star doesn't look good granted I have an AVX and ive never been able to get good guiding anyway
You need to come over one evening and we can take a look at that. I tend to get pretty good guiding with my AVX, though I think I somehow got a good one...
I agree I need to head over and have you help me run through it to make sure I'm doing stuff right
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yobbo89 Australia
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Re: guide scope

#10

Post by yobbo89 »


hi, i have that guide scope, are you using it to image rather then guiding ?, usually halo around stars is a result of chromatic aberration ie different wavelengths are shown at different focus points, a wavelength with a tight sharp focus point ie center of the star and a defocused fridging colour on the edges hence a halo , this is due to the type and quality of the optics system, a result from refractors,refracting light ,and when light travels through something the different wavelengths diffract at different angles , a 3 element refractor helps correction on the defocused wavelength and some two element designs .

other then that if your scope is totally out of focus you usually see an airy disc which is a lot different then a star with a halo, it will be a donut with a black spot in the middle and if you have good seeing and a bit of magnification there will be a dot in the middle.being defcoused like this can be used as a star test i won't go into too much detail ,this is also used to determine the quality of the optics, collimation, and sky conditions , there are variables in the airy disc to determine your sky seeing from 1 to 10 , one of the variables is the center dot staying still which is in the list ,if it does then you have good skys which will about 9-10 seeing, a bit off a wobble is around 6-7 , ectt

posted some images from the net, one is the chromatic aberration , the blue wavelength not in focused causing a halo around the stars and the other is a defocused star during a star test, i hope this gives you an idea of what you're looking at while focusing and imaging
Attachments
Lodriguss.2017.03.01.jpg
post-284012-0-37351200-1510023637.jpg
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .

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yobbo89 Australia
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Re: guide scope

#11

Post by yobbo89 »


if you're guiding with it, then what software are you using? if you have phd it will guide on slightly defocused stars well , it also can show details about the stars profile fwhm (full width half maximum) to see if it's unfocused or a usable star, lower the better

a oversaturated bright star will have the top profile flat and clipped off, this is not an ideal star for guiding (but phd can predict it's center point to some extent),. a star defocused too much will have a wide wfhm., a more in focused star will have a smaller fwhm which is better for guiding so phd can find its center point , more photons going to a focus point, less noise more snr.
Attachments
figure4.jpeg
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .

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yobbo89 Australia
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Re: guide scope

#12

Post by yobbo89 »


This is the star profile you will most likely get after 10 second of imaging , due to turbulent skies shifting the image, ie bad seeing.

you could even say chromatic aberration would have a similar profile.
you'll see the same profile in phd but not as worst because of the quick exposures

here's a crude diagram from paint i put together.
Attachments
star profilexxx.png
star profilexxx.png (5.67 KiB) Viewed 2788 times
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .

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JimMinCT United States of America
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Re: guide scope

#13

Post by JimMinCT »


There's just way too much missing info here to make an educated assumption.
It really shouldn't matter if you have halos in the guide scope. That's not what you're imaging...
PHD actually wants a slightly defocused star for better guiding.

I'm going to make a couple of assumptions and say that you haven't really polar aligned the mount very well, and that you really need to stop by Bryan's to get straightened out. :D
OTA's: Kson 1026-C, 4" Carbon Fiber ED Refractor, Home-built, 6.1", f/2.? APO refractor... (In Progress) 8" Meade LX2 SCT Mounts: CGX Imaging: ZWO ASI 1600MM, Canon 550D (T2i) Software: PixInsight, APT, PHD2, SharpCap, SGP, Stellarium, Registax, Stuff: Astro-Tech 0.8x FR/FF, Hotech SCA FF, ZWO 7nm 31mm LRGB-SHO filter set, ZWO 8 position EFWObsy: "Maybe Spaceship" Observatory
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