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Trouble getting an image with ZWO camera

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#1 Amstel

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Posted 29 January 2023 - 03:03 PM

I am new to all things astronomy. I have an AWB Onesky mounted to a AzGti . I just bought an Asi385 camera and Asiair mini to try and observe during winter. I connected everything according to the instructions. I found Polaris and centered it in my 25mm eyepiece and the focused. Removed 25mm and replaced with 385. Instead of star i see secondary and vane. Thinking it must be focus I tried adjusting the focus but all I get is that same image bigger or smaller. I never see the stars or sky. Should the camera show the sky if i have the 25mm focused before hand???

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Edited by Amstel, 29 January 2023 - 03:07 PM.


#2 DeepSky Di

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Posted 29 January 2023 - 03:24 PM

I am new to all things astronomy. I have an AWB Onesky mounted to a AzGti . I just bought an Asi385 camera and Asiair mini to try and observe during winter. I connected everything according to the instructions. I found Polaris and centered it in my 25mm eyepiece and the focused. Removed 25mm and replaced with 385. Instead of star i see secondary and vane. Thinking it must be focus I tried adjusting the focus but all I get is that same image bigger or smaller. I never see the stars or sky. Should the camera show the sky if i have the 25mm focused before hand???

Both of these images look out of focus. It may help to take the system out in the daytime and try focusing on a distant object. Rack the focuser from one end of its travel to the other and count the turns. Use painter's tape to make marks to see the complete turns. Make a note of how many turns from one end to the other.

 

Another tip: the ASIAIR app has a bullseye overlay which can be used to center the out of focus donut for collimation.



#3 vtornado

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Posted 29 January 2023 - 04:03 PM

Picture 1 in more in focus than Pic #2.

the closer to focus the smaller the spot will be.

If you do not have enough in focus do not extend the AWB all the way out.

If you don not have enough back focus, do not insert the camera all the way into the focuser and/or purchase an

extension tube.



#4 idclimber

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Posted 29 January 2023 - 04:10 PM

Turn the focus whatever direction makes the donut smaller. Keep going until it is a single point of light. If you run out of travel you need to note if it is in-travel or out. Out travel can be fixed with a spacer. In travel might get tricky with a Newtonian Reflector which is what I believe you have?



#5 Amstel

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Posted 29 January 2023 - 04:12 PM

""It may help to take the system out in the daytime and try focusing on a distant object. Rack the focuser from one end of its travel to the other and count the turns" Thanks for the reply
 
 I just took it out and put a bridge light in focus and center of 25mm eyepiece. put camera in and took previews. No matter the focus all i get is a white screen.


Edited by Amstel, 29 January 2023 - 04:15 PM.


#6 Amstel

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Posted 29 January 2023 - 04:24 PM

 

 

Another tip: the ASIAIR app has a bullseye overlay which can be used to center the out of focus donut for collimation.

Thanks I see the bullseye overlay but have no idea what you mean. i collimate with the supplied one.



#7 Amstel

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Posted 29 January 2023 - 04:32 PM

Turn the focus whatever direction makes the donut smaller. Keep going until it is a single point of light. If you run out of travel you need to note if it is in-travel or out. Out travel can be fixed with a spacer. In travel might get tricky with a Newtonian Reflector which is what I believe you have?

Yes it is a Newtonian. The pic with the smaller donut was with the focuser turned all the way in. I ran out of focus adjustment.  Turning focuser out made it larger.



#8 Amstel

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Posted 29 January 2023 - 04:40 PM

Should i be able to see stuff in the daytime with the camera?


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#9 idclimber

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Posted 29 January 2023 - 05:02 PM

Yes it is a Newtonian. The pic with the smaller donut was with the focuser turned all the way in. I ran out of focus adjustment.  Turning focuser out made it larger.

This is a common problem with entry level Newts. They are simply not designed around a camera. The solution is typically to move the primary mirror towards the front of the scope. In your case I wonder if the truss can be shortened, which would accomplish the same thing. I do not know that scope and if that can be done without permanent modifications. Until this is addressed you will not be able to focus that camera. 

 

Look to see if there are any spacers you are using that can be eliminated or shortened. 


Edited by idclimber, 29 January 2023 - 05:04 PM.


#10 Tapio

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Posted 29 January 2023 - 05:03 PM

I see that it's one of those newtonian scopes which are meant for visual and not imaging.
The typical solutions are a) turn the main mirror forward with collimation screws so that focus point moves forward B) use coma corrector or Barlow to move focus point forward c) replace focuser with low profile version.

You can image in daytime but you should decrease exposure time in ms range.

#11 DeepSky Di

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Posted 29 January 2023 - 05:07 PM

Should i be able to see stuff in the daytime with the camera?

Yes. The exposure will have to change to something a lot shorter like .01 or .001 second.



#12 DeepSky Di

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Posted 29 January 2023 - 05:11 PM

Thanks I see the bullseye overlay but have no idea what you mean. i collimate with the supplied one.

One method of collimating is to center an out of focus donut in the center of the field of view and adjust collimation screws until the donut is symmetrical. For this method it's important that the donut is centered. The bullseye overlay helps to center the donut. 



#13 Amstel

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Posted 29 January 2023 - 08:54 PM

This is a common problem with entry level Newts. They are simply not designed around a camera. The solution is typically to move the primary mirror towards the front of the scope. In your case I wonder if the truss can be shortened, which would accomplish the same thing. I do not know that scope and if that can be done without permanent modifications. Until this is addressed you will not be able to focus that camera. 

 

Look to see if there are any spacers you are using that can be eliminated or shortened. 

I was able to shorten the truss tubes and get a bit of a better focus. At least small round things looking much closer to stars. I will have to play with it some more as the weather permits and see if I can clear things up. If I do not get the desired result I will have to look into something else for EAA. Maybe a refractor of some sort.


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#14 Amstel

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Posted 29 January 2023 - 08:57 PM

I see that it's one of those newtonian scopes which are meant for visual and not imaging.
The typical solutions are a) turn the main mirror forward with collimation screws so that focus point moves forward B) use coma corrector or Barlow to move focus point forward c) replace focuser with low profile version.

You can image in daytime but you should decrease exposure time in ms range.

I will try a barlow and see if that helps. And i will try again during the day with your advised settings. Thanks



#15 merill

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Posted 30 January 2023 - 02:12 AM

This is a common problem with entry level Newts. They are simply not designed around a camera. The solution is typically to move the primary mirror towards the front of the scope. In your case I wonder if the truss can be shortened, which would accomplish the same thing. I do not know that scope and if that can be done without permanent modifications. Until this is addressed you will not be able to focus that camera.

Look to see if there are any spacers you are using that can be eliminated or shortened.



#16 merill

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Posted 30 January 2023 - 02:24 AM

yes use the collimation screws to move mirror toward the secondary, absolutly do not mess with the secondary unless it is out of square with the focus tube. You'll have to recollimate and square your primary. Get a autocollimator.

#17 Amstel

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Posted 30 January 2023 - 09:50 AM

yes use the collimation screws to move mirror toward the secondary, absolutly do not mess with the secondary unless it is out of square with the focus tube. You'll have to recollimate and square your primary. Get a autocollimator.

Does collapsing the truss tubes down slightly achieve the same effect as screwing the primary closer?  


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#18 Mike7Mak

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Posted 30 January 2023 - 10:06 AM

I don't know this particular scope but if it's like most newts the primary mirror cell rides on springs over the collimation screws. Moving the primary closer to the secondary with the collimation screws involves unloading those springs which could make collimation very unstable. And I seriously doubt the collimation screws have the necessary length to accomplish the needed adjustment anyway.



#19 idclimber

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Posted 30 January 2023 - 10:11 AM

AWB_Telescope_Poster_v6_no_background_5-8-13_copy_1024x1024@2x.jpg

 

This is the scope. It appears to me the easiest way to modify this scope is to shorten those two truss rods. 


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#20 Amstel

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Posted 30 January 2023 - 11:06 AM

I don't know this particular scope but if it's like most newts the primary mirror cell rides on springs over the collimation screws. Moving the primary closer to the secondary with the collimation screws involves unloading those springs which could make collimation very unstable. And I seriously doubt the collimation screws have the necessary length to accomplish the needed adjustment anyway.

 

I just came in and was able to move the primary quite a bit forward. Collimated. Centered the top of a drawbridge a mile or so away and dropped the camera in. I was then able to focus on the bridge with my helical focuser. So I am hoping I am on the right track. I will post a couple pics to show my view. IMG_2079.PNG IMG_2081.PNG

attachicon.gifAWB_Telescope_Poster_v6_no_background_5-8-13_copy_1024x1024@2x.jpg

 

This is the scope. It appears to me the easiest way to modify this scope is to shorten those two truss rods. 

I also was able to achieve the same focus dropping the rods. Between the two options I am hopefull to get some decent images of the sky from the camera at night next decent evening.


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#21 fuadramsey

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Posted 30 January 2023 - 11:34 AM

Correct, for the AWB scope you just don't extend the truss all the way out. Put your camera in place and give a few mm of room for the focuser to move around. Adjust the focus point by moving the truss in until you get focus as good as you can. Once you do that you fine tune the focus with the focuser. 

 

Visit the AWB mega thread for more info: 

https://www.cloudyni...2#entry12340210

 

I got to view and capture the lunar occultation in December:

post-28279-0-30098500-1670522403.jpg


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#22 Amstel

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Posted 02 February 2023 - 08:10 AM

I just wanted to thank everyone in this thread for their help. Had a great evening playing around and captured many things I never thought possible. Thanks to you guys I am off on a new adventure. With lots to learn. So this Bud is for you! Clear skies guys.

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#23 merill

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Posted 15 February 2023 - 02:02 AM

Does collapsing the truss tubes down slightly achieve the same effect as screwing the primary closer?  

should.




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