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Andromeda ZWOASI

astrophotography cassegrain Celestron dso imaging SCT
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#1 arshadwm

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Posted 19 January 2021 - 05:09 PM

Dear All. I need the following information and guidance to take image of Andromeda Galaxy through My Camera is ZWOASI294 MC PRO and my Telescope is Celestron CPC EDGEHD 1100 with Starizona Hyperstar 3. 

 

How many 

 

Light Frames ? Gain ? Exposure in seconds 

Dark Frames ? Gain ? Exposure in seconds

Flat Frames ? Gain ? Exposure in seconds 

Bias Frames ? Gain ? Exposure in seconds 

 

also please advise, do I have to cover the front corrector plate with black cover to take Dark and Bias frames and white cover to take Flat frames ? 

 

I also have Optolong LExtreme and LPro Filters. 

 

Amy suggestion, idea or better way to take the unstacked images will be appreciated. 

 

 



#2 petert913

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Posted 19 January 2021 - 05:54 PM

That would be cheating.  You have to struggle through months of trial and error as we all did  !! lol.gif


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#3 pedxing

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Posted 19 January 2021 - 07:23 PM

There are many techniques for taking flat frames, the simplest equipment-wise is to stretch a white t-shirt over the front of the scope and take the frames during twilight. Flats must be taken with the camera on the scope in the same orientation as the lights.

 

Darks and bias can be taken when the camera is not on the scope, just cap the camera and take the frames. It can be helpful to do this in a dark place in case of light leaks. I do it in the refrigerator to ease the load on the camera cooler.

 

For M31, I wouldn't use any filters.

 

Exposure/gain for lights, you do kind of have to experiment. Once you determine what you are going to use, then you need darks that match the lights as far as exposure time, gain and temperature. Bias should match the lights for gain and temperature, but use the shortest exposure time that your camera will support.

 

Darks - 20 to 30 frames.

Bias - 20 to 50 frames.

Flats - 20 frames

Lights - As many frames as possible.


Edited by pedxing, 19 January 2021 - 07:29 PM.

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#4 arshadwm

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Posted 23 January 2021 - 02:40 PM

Thank You v much vanguard. God bless. 



#5 copper280z

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Posted 23 January 2021 - 07:20 PM

I'd probably start with gain at 120, then increment exposure time until you can see the full bell curve in the histogram, and it's off the left edge. The CPC is an alt-az mount, so if you go too long in exposure you'll get star trails from field rotation, if that happens then back exposure down until no trails, then turn gain up until you get the whole histogram bell curve and it's off the left edge.

 

Write these settings down, you need to take darks with these exact settings.

No filters for andromeda, it's a broad band target.



#6 Stelios

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Posted 23 January 2021 - 07:24 PM

Please, please, please at the very least buy a wedge and stop torturing yourself with the Alt-Az mount. 


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#7 arshadwm

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Posted 24 January 2021 - 09:47 AM

@voyager I do have wedge installed with Starizona Hyperstar 



#8 arshadwm

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Posted 24 January 2021 - 09:48 AM

Thank You Vostok. I’m at Bortle 8 so I think I do need LExtreme Optolong. 



#9 jonnybravo0311

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Posted 24 January 2021 - 10:54 AM

Thank You Vostok. I’m at Bortle 8 so I think I do need LExtreme Optolong. 

Not if you're targeting Andromeda. Those filters are good for emission nebulae (heart, soul, horse head, North America, California, etc). They are NOT for broadband targets or reflection nebulae (Andromeda, Triangulum, Bode's, Pleiades, etc).


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#10 arshadwm

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Posted 24 January 2021 - 04:19 PM

Thank You dear. Secondly. It’s very inconvenient to dismantle the camera and cap on. Instead I’ve made one white and one black plastic round sheet to cover the corrector plate. Do you think it’s a good idea ? Please check the attachment of the white sheet. 

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#11 Stelios

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Posted 24 January 2021 - 08:14 PM

Thank You dear. Secondly. It’s very inconvenient to dismantle the camera and cap on. Instead I’ve made one white and one black plastic round sheet to cover the corrector plate. Do you think it’s a good idea ? Please check the attachment of the white sheet. 

You take the camera off *ONE* time, and take the darks correctly (in a fridge). Take them for all the likely exposure lengths and temperatures (should not be more than 6 to 10 combos).

 

After that, you integrate the darks into masters, and reuse them for at least one year. 

For flats, since you don't remove the camera, you can also likely get away with taking them rarely. 



#12 jonnybravo0311

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Posted 24 January 2021 - 10:42 PM

You take the camera off *ONE* time, and take the darks correctly (in a fridge). Take them for all the likely exposure lengths and temperatures (should not be more than 6 to 10 combos).

 

After that, you integrate the darks into masters, and reuse them for at least one year. 

For flats, since you don't remove the camera, you can also likely get away with taking them rarely. 

Why in a fridge? The 294MC Pro has TEC.

 

Does it go in the crisper drawer? :D




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