Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Focusing guide camera in N.I.N.A

  • Please log in to reply
28 replies to this topic

#1 Stevo_K

Stevo_K

    Lift Off

  • -----
  • topic starter
  • Posts: 11
  • Joined: 06 Oct 2023

Posted 01 April 2024 - 08:46 PM

I'm brand new to NINA.  I've watched a number of videos on setting up and imaging, however, I've not yet seen any information on how to focus a guide camera using NINA...

Does anyone have pointers? Or can someone point me to the appropriate documentation/ video/ etc?

 

 

 



#2 Quadstronomer

Quadstronomer

    Mariner 2

  • *****
  • Posts: 207
  • Joined: 27 Sep 2019
  • Loc: East TN

Posted 01 April 2024 - 09:21 PM

Does your guide scope have an EAF, is it connected to NINA? If so, this is easy as pie. Just connect your guide camera instead of your imaging camera. Find autofocus window, select start autofocus.


  • dswtan and Juno18 like this

#3 Jim Waters

Jim Waters

    Cosmos

  • *****
  • Posts: 8,778
  • Joined: 21 Oct 2007
  • Loc: Phoenix, AZ USA

Posted 01 April 2024 - 10:36 PM

Guide cameras are manually focused by looping on a dim star while using your guiding software such a PHD2.


Edited by Jim Waters, 01 April 2024 - 10:36 PM.

  • Oort Cloud and DirtyRod like this

#4 ayadai

ayadai

    Apollo

  • *****
  • Posts: 1,142
  • Joined: 01 Feb 2021
  • Loc: Northern Mariana Islands

Posted 01 April 2024 - 10:50 PM

Set the main camera as your guide cam, point at a clear part of the sky with medium bright stars, turn on looping and set the exposure to 1 second in the imaging tab, and then switch to the image tab and watch it while adjusting focus. Change the camera back to the main cam before starting imaging.

 

I prefer not to use the image display in PHD2, as it is not as large nor as clear as the one in NINA.


Edited by ayadai, 01 April 2024 - 10:53 PM.

  • Juno18 likes this

#5 Marcelofig

Marcelofig

    Apollo

  • -----
  • Posts: 1,126
  • Joined: 21 Jan 2015

Posted 01 April 2024 - 11:20 PM

Dark Sky Geek has an interesting project, a focusing motor designed for guide cameras.
 

https://www.youtube....h?v=GP4CpIjJSqA



#6 rgsalinger

rgsalinger

    James Webb Space Telescope

  • *****
  • Posts: 15,966
  • Joined: 19 Feb 2007
  • Loc: Carlsbad Ca

Posted 02 April 2024 - 12:39 AM

Odd. I prefer to use the display in PHD as I can size it as large as I want it to be and I get statistics as I'm focusing the guide camera. Are you using a PC? 



#7 acrh2

acrh2

    Mercury-Atlas

  • *****
  • Posts: 2,823
  • Joined: 16 Mar 2021

Posted 02 April 2024 - 01:47 AM

Guide cameras are manually focused by looping on a dim star while using your guiding software such a PHD2.

Why did you say "dim star?"


  • Quadstronomer likes this

#8 Robert7980

Robert7980

    Soyuz

  • -----
  • Posts: 3,616
  • Joined: 20 Nov 2022
  • Loc: Western North Carolina

Posted 02 April 2024 - 02:01 AM

I use SharpCap for guider focusing and just general rough focus of the main camera, it’s just easier and faster. 


  • Juno18, Sacred Heart, Borodog and 1 other like this

#9 Sacred Heart

Sacred Heart

    Fly Me to the Moon

  • *****
  • Posts: 5,308
  • Joined: 16 Aug 2020

Posted 02 April 2024 - 02:33 AM

I use SharpCap for guider focusing and just general rough focus of the main camera, it’s just easier and faster. 

I'll second and third this. I also use a Bahtinov mask, but I also use a 76mm refractor to guide.  

 

Just remember to close the camera in Sharpcap before going to PHD2 or you'll get an error. Two programs cannot operate the same camera at two different exposures at the same time.

 

Joe


  • Borodog likes this

#10 Juno18

Juno18

    Viking 1

  • *****
  • Posts: 895
  • Joined: 07 Dec 2018
  • Loc: Long Beach, Mississippi, USA

Posted 02 April 2024 - 05:14 AM

Someone might have mentioned this.

I think that you can get close enough during the daytime to make focusing on stars at night a breeze.

Just point scope at the most distant object that you can (cell tower or trees/house).

If you still have the finder bracket on the scope it is helpful to temporarily use a finder for pointing.

I like to use Sharpcap for this because it is easy.

Set Sharpcap to auto exposure and gain and it will have no problem getting the camera adjusted.

 

I have focused through a window (too lazy to drag everything outside), but some sharpness is lost through the window. It is much easier to see the laptop display though.

 

Easy peasy. Good luck!


Edited by Juno18, 02 April 2024 - 05:15 AM.

  • Sacred Heart and Borodog like this

#11 unimatrix0

unimatrix0

    Fly Me to the Moon

  • *****
  • Posts: 6,800
  • Joined: 03 Jan 2021

Posted 02 April 2024 - 07:48 AM

Focusing a guide camera using a mini pc or laptop is not difficult.  I also use Sharpcap, becuase I have it, but it can be done with NINA too.  Create a new profile in NINA which is your guide scope camera as your main. Loop your camera exposure 1-2 seconds in the imaging window and focus your stars either by making them small as possible or if you got a bathinov mask for the guide scope if you want to be super precise.  Again, you can get away by just eyeball the focus on an enlarged view of the stars and making them small as poosible.  

 

My own method is that I got a Lenovo Yoga laptop with Sharpcap Pro installed and I directly plug my guide camera into the laptop before any imaging, so I got a nice large view and just make the stars as small as possible.  You can also polar align the fastest way this way too, I just pay the $15 yearly suscription for the pro, it's just so worth it. 

 

Also, If you would ever want to do planetary or solar or lunar imaging, Sharpcap pro is king. 


  • Sacred Heart and Borodog like this

#12 Juno18

Juno18

    Viking 1

  • *****
  • Posts: 895
  • Joined: 07 Dec 2018
  • Loc: Long Beach, Mississippi, USA

Posted 02 April 2024 - 08:18 AM

$15 for Sharpcap Pro is one of the best bargains going. You will need the pro version to PA (yes, it is really fast like Frank said).

 

For guide scope focusing, the free version works well.


  • Sacred Heart and Borodog like this

#13 Borodog

Borodog

    Voyager 1

  • *****
  • Posts: 11,126
  • Joined: 26 Oct 2020
  • Loc: St. Augustine, FL

Posted 02 April 2024 - 08:27 AM

I had a friend 3D print me some B mask “caps” for my 30mm guide scopes. Luckily they also fit my 40mm. I focus in SharpCap with the B mask. Set the exposure to 1/8 s so the response is snappy and smooth and turn up the gain. Very easy to focus.

Also, polar alignment in SharpCap is awesome. So quick and easy. Worth the price of the pro version just for that alone, but it has so much more.

Edited by Borodog, 02 April 2024 - 08:29 AM.

  • rgsalinger and Sacred Heart like this

#14 Stevo_K

Stevo_K

    Lift Off

  • -----
  • topic starter
  • Posts: 11
  • Joined: 06 Oct 2023

Posted 02 April 2024 - 12:13 PM

Thanks everyone for the advice.  I'll give the PHD2 method a try as soon as I get a clear night


  • Sacred Heart likes this

#15 Quadstronomer

Quadstronomer

    Mariner 2

  • *****
  • Posts: 207
  • Joined: 27 Sep 2019
  • Loc: East TN

Posted 02 April 2024 - 05:47 PM

Why did you say "dim star?"

because a large bright star will likely be saturated which will likely have many pixels to reference, instead of the ideal single pixel. 

 

for example: 

Attached Thumbnails

  • pixel star example.jpg

  • Jim Waters likes this

#16 rgsalinger

rgsalinger

    James Webb Space Telescope

  • *****
  • Posts: 15,966
  • Joined: 19 Feb 2007
  • Loc: Carlsbad Ca

Posted 02 April 2024 - 06:46 PM

Sorry I really don't see that need to learn Sharpcap to focus a guide camera quickly if you have PHD already (or even NINA itself). What you actually want to do is to point the scope at someplace in the Milky Way. That will give you lots of stars. Now just use long exposures (5 seconds is best) with PHD running to focus the guide scope camera.

 

Also, if you want  to get "close" during the day, remember that you will have to use millsecond exposures if you are in bright daylight.

 

When starting out it's hard enough to just get the mount to find the moon (IME) let alone accurately locate bright star. PHD will give you all the information that  you need - HFD to attain excellent  focus. One other thing to bear in mind is that the difference between in focus and out of focus is very small. 

 

I have sharpcap pro and use it for planetary but NINA has everything that you can realistically ever need for DSO imaging. Oh and the Pro license is ANNUAL, unless something has changed. 


Edited by rgsalinger, 02 April 2024 - 06:48 PM.


#17 acrh2

acrh2

    Mercury-Atlas

  • *****
  • Posts: 2,823
  • Joined: 16 Mar 2021

Posted 02 April 2024 - 06:53 PM

because a large bright star will likely be saturated which will likely have many pixels to reference, instead of the ideal single pixel. 

 

for example: 

Don't you need a bright star to see diffraction spikes from a Bahtinov mask?



#18 Sacred Heart

Sacred Heart

    Fly Me to the Moon

  • *****
  • Posts: 5,308
  • Joined: 16 Aug 2020

Posted 02 April 2024 - 07:25 PM

Don't you need a bright star to see diffraction spikes from a Bahtinov mask?

My experience, I'm going to say no, but brighter is best..clearer definition.

 

Just me,   Joe



#19 Quadstronomer

Quadstronomer

    Mariner 2

  • *****
  • Posts: 207
  • Joined: 27 Sep 2019
  • Loc: East TN

Posted 02 April 2024 - 08:07 PM

Don't you need a bright star to see diffraction spikes from a Bahtinov mask?

using a mask is a visual aid for human eyes, which can get sufficiently close. But computers use centroid diameters measured in pixels/microns, which is far more accurate. 



#20 Borodog

Borodog

    Voyager 1

  • *****
  • Posts: 11,126
  • Joined: 26 Oct 2020
  • Loc: St. Augustine, FL

Posted 02 April 2024 - 08:11 PM

using a mask is a visual aid for human eyes, which can get sufficiently close. But computers use centroid diameters measured in pixels/microns, which is far more accurate. 

He's focusing a guide camera. It doesn't have an autofocuser. He's not measuring FWHMs or HFRs while focusing it. He's just trying to figure out the easiest/best way to get it focused.


  • rgsalinger and acrh2 like this

#21 Robert7980

Robert7980

    Soyuz

  • -----
  • Posts: 3,616
  • Joined: 20 Nov 2022
  • Loc: Western North Carolina

Posted 02 April 2024 - 10:00 PM

Sorry I really don't see that need to learn Sharpcap to focus a guide camera quickly if you have PHD already (or even NINA itself). What you actually want to do is to point the scope at someplace in the Milky Way. That will give you lots of stars. Now just use long exposures (5 seconds is best) with PHD running to focus the guide scope camera.

 

Also, if you want  to get "close" during the day, remember that you will have to use millsecond exposures if you are in bright daylight.

 

When starting out it's hard enough to just get the mount to find the moon (IME) let alone accurately locate bright star. PHD will give you all the information that  you need - HFD to attain excellent  focus. One other thing to bear in mind is that the difference between in focus and out of focus is very small. 

 

I have sharpcap pro and use it for planetary but NINA has everything that you can realistically ever need for DSO imaging. Oh and the Pro license is ANNUAL, unless something has changed. 

SharpCap is literally opening the program, selecting the camera and your off to the races… Has to be the simplest fewest steps of any software or method… It’s got very low overhead so you get fast frame rates, even my 2600 is a video camera when running through SharpCap, and if needed there are very easy to use adjustments for binning and camera settings to adjust gain and exposure.

 

Thats what I was referring to anyway, not doing any detailed analysis or anything other than maybe zooming in a little… It pulls frames in much much faster than NINA and PHD makes it a difficult to change camera settings and if your in a working guiding profile you’ll have to undo everything once your done focusing, with SharpCap you just close the program and your done… 

 

Also using the free version to do so…


Edited by Robert7980, 03 April 2024 - 12:27 AM.

  • Juno18 likes this

#22 acrh2

acrh2

    Mercury-Atlas

  • *****
  • Posts: 2,823
  • Joined: 16 Mar 2021

Posted 03 April 2024 - 12:18 AM

using a mask is a visual aid for human eyes, which can get sufficiently close. But computers use centroid diameters measured in pixels/microns, which is far more accurate. 

It thought it would be important to mention the following point since no one else mentioned it (not directly related to the statement you made above, which is correct.)

1) While the guide scope doesn't have to be perfectly focused to afford adequate guiding, PHD2 does guide better with a perfect focus - the centroid calculations are more precise with better focus. PHD2 developers have commented on that in the past.

2) Unless you plan on focusing your guide scope every time you image, the temperature changes between seasons or even during a single session will take your guide scope out of focus.

 

The point: when you are already slightly out of focus and the temperature changes, you might be even more out of focus if the change is in the same direction. And that's when you start having issues. So having the best focus possible is kind of important. That's where the Bahtinov mask comes in.

I have tried focusing guide scopes with PHD2, NINA and Sharpcap by simply reading HFR measurements, and it's a slow and inaccurate process. It's so much easier and more precise to use a Bahtinov mask. I would usually focus my guide scopes in the spring or fall and kind of forget about it for a few years.

So use Bahtinov mask, it's faster, more precise and more expensive :)


  • Robert7980 likes this

#23 rgsalinger

rgsalinger

    James Webb Space Telescope

  • *****
  • Posts: 15,966
  • Joined: 19 Feb 2007
  • Loc: Carlsbad Ca

Posted 03 April 2024 - 02:24 AM

Well, I politely disagree with almost all of this. I'd like to see some links to posts from the PHD developers emphasizing that "precise focus" allows for a better centroid calculation. If they do say that then I'll have to change my way of thinkiing. 

 

Personally I find focusing with a mask much slower and less accurate than simply moving the focuser out just a bit and looking at the result. 

 

While I always do, in fact, try to get accurate focus, it doesn't take much time at all to use PHD to get focus good enough to give me excellent guiding RMS and star size.

 

To me, though,it's all pretty irrelevant because if you use a guide scope or you use and OAG, you just have to focus the thing once and your done. Just either keep the camera attached to the guide scope and in focus with the focuser locked or make a mark so that you can get back to correct focus in a jiffy. 


Edited by rgsalinger, 03 April 2024 - 02:25 AM.

  • AstroOlly likes this

#24 AstroOlly

AstroOlly

    Mariner 2

  • -----
  • Posts: 201
  • Joined: 25 Oct 2013
  • Loc: In my AstroShed

Posted 03 April 2024 - 03:39 AM

I absolutely agree with @rgsalinger above, focus for the guide camera and scope is not critical at all, in fact the guys at PHD, namely Craig Stark who wrote the original PHD before it became PHD2, said that a slightly out of focus guide star is better…there really is no need for any major time spent on this at all, just look at the screen and focus until the star looks in focus and away you go, I have never used a Bahitnov mask for focusing a guider, and never would it’s just overkill..



#25 acrh2

acrh2

    Mercury-Atlas

  • *****
  • Posts: 2,823
  • Joined: 16 Mar 2021

Posted 03 April 2024 - 03:48 AM

I absolutely agree with @rgsalinger above, focus for the guide camera and scope is not critical at all, in fact the guys at PHD, namely Craig Stark who wrote the original PHD before it became PHD2, said that a slightly out of focus guide star is better…there really is no need for any major time spent on this at all, just look at the screen and focus until the star looks in focus and away you go, I have never used a Bahitnov mask for focusing a guider, and never would it’s just overkill..

And I read exactly the opposite on this forum. 

The person, whose name I don't remember, was commenting about a developer of PHD2 saying explicitly that latest algorithm of centroid calculation will benefit from the best focus. And that defocusing of guide stars is a thing of the past.

 

This is from PHD2 manual:

 

If you are just starting with your equipment set-up, it's critical that you carefully focus the guide camera.

 

This is from PHD2 forum/developer:

 

 

Hi Bob,

I would not recommend defocusing.  You want the highest SNR and max number of guide star choices. If you defocus you will lose those. Defocusing is sometimes indicated when the stars are highly under-sampled like if you guide image scale is up around 7-10"/px or higher and much higher than your imaging camera pixel scale -- I doubt that applies as you are using OAG.  With OAG especially you want the focus to be as tight as possible.

Could you post a sample image where you did not like PHD2's choice so we can evaluate it.  Use File > Save Image in PHD2, then post the FITS file as an attachment. Could you also post the Debug Log and Guide Log files from the session.  We can't really make any recommendation without seeing the data.

Andy

 

Same developer:

 

 

Hi Aaron,

tl;dr : With an OAG you should go for the sharpest focus. This is especially true if you are using an AO and attempting short exposures.

When you defocus, you are trading-off SNR, and decreased SNR increases the uncertainty in the centroid calculation. Only if your star "diameter" is less than about one pixel, then you should consider de-focusing a bit.  The star profile tool will show you the half-flux diameter (HFD) of your guide star. If your HFD is close to 1.0 or lower, then you may consider de-focusing a little bit.  This would be the case with short focal length guide scopes and/or large guide camera pixels.  With your OAG you're going to have "fat" stars, unless your guide cam has really large pixels. Trying to get short exposures for your AO you're going to want to maximize your SNR by focusing as tightly as possible.

Andy


Edited by acrh2, 03 April 2024 - 03:57 AM.

  • michael8554 likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics