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Sharp Cap - Could not align

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#1 Guydive

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Posted 25 March 2020 - 05:17 PM

First EAA session, looks like I have a ton to learn.

First thing, I could not stack anything that wasn't a bright cluster.
setup is skywatcher goto 10" dob + zwo 178mm
I couldn't get sharpcap to stack, kept getting a 'could not align' message. This capture is for M65:

90699A19 BECD 4472 891F 3661F203F858

I guess It didn't read enough stars? 

 

Also is there a short crash course for using this thing? seems like I need something methodic 



#2 jerahian

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Posted 25 March 2020 - 05:25 PM

Yes, I believe your issue was not enough stars.  Did you try increasing the exposure from 5s to maybe 20s?



#3 Guydive

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Posted 25 March 2020 - 05:41 PM

Yes, I believe your issue was not enough stars. Did you try increasing the exposure from 5s to maybe 20s?

I tried 10 but it didn't seemed like it was getting better

#4 S.Boerner

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Posted 25 March 2020 - 05:45 PM

There are lots of Youtube videos on how to use SharpCap.  This is a good stacking start.  

 

What's your FOV?



#5 Gamewarden

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Posted 25 March 2020 - 06:23 PM

Under the alignment tab there are lots of variables that will either make stars harder to find or easier. I use the yellow boxes to get some idea on what Sharpcap can see. I have the same problem maybe my small chip camera . 3 by .22 FOV.



#6 donstim

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Posted 25 March 2020 - 08:13 PM

As Gamewarden alluded to, we would need to see the settings you have under the alignment tab. First, check the box "Highlight Detected Stars" so you can see what, if anything, is being detected as stars. Begin by increasing the digital gain setting, one step at a time. If there are obvious large bright stars that are not being detected, try increasing the Maximum star width. If there are tiny stars that you can see, but that are not being detected, you can try lowering the Minimum star width. You can also try lowering the Black level threshold and the reduce noise setting.

 

If it then starts detecting plenty of stars, make sure they are actually stars and not hot pixels or noise (or simply too many stars). If so, then increase the noise reduction and/or the black level threshold. 

 

Alas, if your FOV is very small, there may well be times that not enough stars will be visible to SharpCap to align the frames.

 

Hope this helps.


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#7 mikenoname

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Posted 25 March 2020 - 08:18 PM

Given the long focal length of the 10 inch dob, and the relatively small half-inch sensor of the 178, I would have to agree that your field-of-view is so small that SharpCap did not have sufficient background stars to align.

 

My recommendation, if your signature is correct as to the equipment you have, is to switch to the 130 rather than the 10 inch. Much shorter focal length which will give you a much larger field-of-view. I actually have the same exact Newtonian scope and love using it with my 178.



#8 Rickster

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Posted 26 March 2020 - 12:11 AM

Glad to see you pulled the trigger on a camera and are in the process of climbing the learning curve.  Looks to me like you have gotten the right advice.


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#9 Guydive

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Posted 26 March 2020 - 12:28 AM

Glad to see you pulled the trigger on a camera and are in the process of climbing the learning curve. Looks to me like you have gotten the right advice.

Thanks Rick. I'm going to start with all the software advice I just got. But just of curiosity, on the previous subject we talked about, if I want to shorten my focal length using the trusses, how can I calculate where the camera needs to be located? I guess I will need to take it outside the focus tube, and I can 3D print an extension and clippers to hold the trusses in their new position. Or maybe it's in? I remember I spoke with a Mallincam dealer who told me one of his clients did that and got his camera closer to the secondary with a 3d printed holder (in that case the zwo cannot slide pass the 2" hole)

Edited by Guydive, 26 March 2020 - 12:35 AM.


#10 Rickster

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Posted 26 March 2020 - 01:12 AM

If I understand your question correctly, you are wanting to add a focal reducer to increase your field of view and you are wondering how much you will need to collapse your scope, right?

 

You will need to shorten (collapse) your tube by zero to 2 inches depending on where you currently are in the focuser's range of travel and which focal reducer you choose.  If you choose one of the cheap 1.25in FRs, and you have some in travel left, you might not need to change anything.  Here is some good info on how it works.    https://agenaastro.c...cers-guide.html



#11 nic35

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Posted 26 March 2020 - 08:14 AM

For a crash course, try post #91 in the following topic  https://www.cloudyni...al#entry9581288


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#12 Guydive

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Posted 26 March 2020 - 11:15 AM

For a crash course, try post #91 in the following topic  https://www.cloudyni...al#entry9581288

Thanks. very handy! 

Basically repeting what donstim wrote. now I just need to wait for a clear night undecided.gif



#13 chilldaddy

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Posted 26 March 2020 - 06:43 PM

There are well over twenty stars visible in your screen shot suggesting that FOV and exposure length are not the problem.  I would follow donstim's advice as well and work on the alignment settings.  That is often the most challenging part of live stacking. 

 

Also, if your mount isn't tracking well or it's windy, you may find that longer exposures only make it harder for Sharpcap to clearly see stars usable for tracking. 

 

I too found the Unofficial Sharpcap Guide produced by Astrojedi a great place to start.

 

EAA is both challenging and exhilarating.  Welcome to the club! smile.gif

 

Greg


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#14 Stargazer3236

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Posted 27 March 2020 - 02:19 PM

In order to align your images, you need to play with the Digital gain under the alignment tab. Try 2X and if that does not work, push it to 4X and then 8X. Sometimes if you have too many stars, just turn it off. But play with the Digital Gain to get your images to align. Also, make sure your minimum star size is set to 1 and your maximum is set to32. Set your black level to 50. On the left side of your live stack screen, set your align using to 25 stars, the max you can go. This should all help you with your aligning stars for stacking images. Remember to adjust your digital gain, depending on how many bright stars are available or not available.

 

Set your Sigma clipping to on under the stacking tab. Under enhancement, click on Unsharp Masking, to give you sharper details in your stacked images. Play with the radius slier and the amount slider. Too much Unsharp masking will put dark halos around your stars, but your nebulous detail will be sharper. Try to find the best balance between the two.


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#15 mikenoname

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Posted 27 March 2020 - 02:41 PM

Also, make sure your minimum star size is set to 1 and your maximum is set to32.

Be careful with setting the minimum star size too low because if you do so, the alignment algorithm will interpret stray hot pixels on your sensor as background stars and your alignment will not be what you desire. I find I can't go much below 3 before I start running into issues.


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#16 Guydive

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Posted 03 April 2020 - 09:12 AM

thanks all for your inputs. I've been waiting for a clear night and yesterday my prayers were answered. eventually, I was able to get my first proper EAA view, M63 - exciting!

I think that the next phase is to learn how to balance everything properly

 

MM63

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#17 Stargazer3236

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Posted 03 April 2020 - 08:05 PM

thanks all for your inputs. I've been waiting for a clear night and yesterday my prayers were answered. eventually, I was able to get my first proper EAA view, M63 - exciting!

I think that the next phase is to learn how to balance everything properly

 

Very good! All it takes is asking the right questions and getting the right answers. Everyone on here is willing to help out everyone else with their problems. This website is a great resource to those in need of answers.



#18 Guydive

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Posted Yesterday, 12:04 AM

I'm looking for a cheap focal reducer to play with but have no Idea where to start. Will this one do?
https://www.firstlig...al-reducer.html

#19 Stargazer3236

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Posted Yesterday, 04:29 PM

This one is good, I have two: https://agenaastro.c...al-reducer.html

This one is pretty cheap as well: https://www.ebay.com...aYAAOSwhcNaVwZw


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