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First sharpcap images - problem..

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#1 Cotts

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Posted 17 May 2021 - 11:11 AM

M57, imaged with ASI224 colour CMOS, through an AstroTech 65mm Quad APO refractor, f.l.420mm.   I'm learning Sharpcap with this little scope so as to be ready for my 20" f/3.3 dob in the fall....

 

30 frames of 10 seconds each with gain at 291... Converted the image from FITS to JPEG in Nebulosity, re-sized for CN..... 

 

The little coloured squiggles are the problem....  My guess is that they are hot pixels in the camera which move around as the software stacking 'moves' the frame to align the stars.......  My goodness there are a lot of them!!!

 

I'm using the "free" version of Sharpcap which does not allow dark-frame subtraction. 

 

My guess for the solution is to pony up the money for the full version of Sharpcap and do the dark subtraction.....

 

Here is the image... all the rest of my shots last night look the same....

 

M57-2.jpg

 

Thanks for the assistance.

 

Dave


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#2 alphatripleplus

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Posted 17 May 2021 - 11:20 AM

M57, imaged with ASI224 colour CMOS, through an AstroTech 65mm Quad APO refractor, f.l.420mm.   I'm learning 

The little coloured squiggles are the problem....  My guess is that they are hot pixels in the camera which move around as the software stacking 'moves' the frame to align the stars.......  My goodness there are a lot of them!!!

 

I'm using the "free" version of Sharpcap which does not allow dark-frame subtraction. 

 

My guess for the solution is to pony up the money for the full version of Sharpcap and do the dark subtraction.....

 

 

Yep, those are hot pixels and dark subtraction will take care of them, as well as the amp glow that you may have with the camera.

 

You can either subscribe to the Pro version of SharpCap (which is well worth it, even if you use it just for the PA routine), or you can use ZWO's ASILive EAA software which is free and will do dark subtraction. I have a paid SharpCap Pro subscription, but I tend to use ASILive more nowadays. SharpCap Pro has many more bells and whistles than ASILive, and that can be part of its appeal for many users. I think both are great tools, and you will hear varying opinions about one vs the other. My advice is try both and make up your own mind.


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#3 Broglock

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Posted 17 May 2021 - 12:58 PM

Ditto!



#4 Cotts

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Posted 17 May 2021 - 01:38 PM

Thanks for the quick feedback.  I need y'all to help me spend my money....grin.gif

 

Supplementary question, Mr. Speaker:  Assuming i take suitable darks and flats does SharpCap apply them 'on the fly' as well?

 

That would be primo!!!

 

Dave



#5 bips3453

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Posted 17 May 2021 - 02:21 PM

Yes, SharpCap applies dark and flat frames during live stacking. 



#6 alphatripleplus

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Posted 17 May 2021 - 02:21 PM

Yep, SharpCap and ASILive and other EAA software apply darks and flats  on-the-fly - part and parcel of the near "live viewing" EAA experience. Would be a pain if you had to wait until afterwards to get the effect of these calibrations, as the live viewing experience would not be so good.



#7 bips3453

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Posted 17 May 2021 - 02:25 PM

M57, imaged with ASI224 colour CMOS, through an AstroTech 65mm Quad APO refractor, f.l.420mm.   I'm learning Sharpcap with this little scope so as to be ready for my 20" f/3.3 dob in the fall....

 

30 frames of 10 seconds each with gain at 291... Converted the image from FITS to JPEG in Nebulosity, re-sized for CN..... 

 

The little coloured squiggles are the problem....  My guess is that they are hot pixels in the camera which move around as the software stacking 'moves' the frame to align the stars.......  My goodness there are a lot of them!!!

 

I'm using the "free" version of Sharpcap which does not allow dark-frame subtraction. 

 

My guess for the solution is to pony up the money for the full version of Sharpcap and do the dark subtraction.....

 

Here is the image... all the rest of my shots last night look the same....

 

attachicon.gifM57-2.jpg

 

Thanks for the assistance.

 

Dave

Saw in another post from you that you are using an equatorial mount. These artifacts would indicate that your polar alignment is a little bit off. 




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