Hi,
I've spent four nights, ten hours in total trying to use the Polar Align feature.
I'm using a Celestron Nexstar 8 SE with a Celestron AVX mount.
ZWO ASI585MC camera with proper back focus.
Mount is pointing roughly true north using a compass.
Stars are in focus using a Bahtinov Mask.
Startup Sharpcap. Select camera. Select Polar Align.
Step 1 solves in seconds.
Step 2 solves a little bit longer.
Final step, I either start making mount adjustments or I just touch the alt/az alignment nobs and I get the following,
"Warning: The last xxx frames failed to solve. Check your star detection settings and camera exposure/gain".
When I get this message, I have anywhere from 42 to 22 stars detected. I've changed the exposure and gain to every to every possible setting and the same with Star Detection.
I restart and do it all over again and keep getting the same error message. I checked the Troubleshooting Polar Alignment but couldn't find anything to fix this.
Hoping someone can point me in the right direction to help me solve this issue.
Bob
Frames Failed To Solve
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Re: Frames Failed To Solve
Hi Bob,
if you are using the 585 camera on the 8SE for polar alignment then the problem is that your field of view is too small - I just ran the numbers through a field-of-view calculator (https://astronomy.tools/calculators/field_of_view/) and it comes out at 0.31x0.18 degrees. The recommended minimum FOV for polar alignment is 0.6 degrees, so you can see that you are well below that threshold. Basically you end up with the small are you are looking at not always having enough stars in SharpCap's internal alignment database to match the pattern of stars seen by the camera.
You essentially have three ways to get a wider FOV
* Bigger sensor camera (expensive)
* Shorter focal length telescope (if you have a guide scope, put the camera on that - the field of view will be fine)
* Some sort of focal reducer (you might just get away with using a cheap(ish) 0.5x reducer that screws into the filter thread - others have had some success that way, but the image quality can be a bit poor, so not guaranteed).
cheers,
Robin
if you are using the 585 camera on the 8SE for polar alignment then the problem is that your field of view is too small - I just ran the numbers through a field-of-view calculator (https://astronomy.tools/calculators/field_of_view/) and it comes out at 0.31x0.18 degrees. The recommended minimum FOV for polar alignment is 0.6 degrees, so you can see that you are well below that threshold. Basically you end up with the small are you are looking at not always having enough stars in SharpCap's internal alignment database to match the pattern of stars seen by the camera.
You essentially have three ways to get a wider FOV
* Bigger sensor camera (expensive)
* Shorter focal length telescope (if you have a guide scope, put the camera on that - the field of view will be fine)
* Some sort of focal reducer (you might just get away with using a cheap(ish) 0.5x reducer that screws into the filter thread - others have had some success that way, but the image quality can be a bit poor, so not guaranteed).
cheers,
Robin
Re: Frames Failed To Solve
Hi Robin!
Thank you for the reply. And thank you for doing FOV test for me. I'm still learning.
Apologies to you for not mentioning that I do have a Celestron 6.3 focal reducer. I did the FOV calculations on astronomy.tools and the FOV comes up at 1.22
I'm still not sure why I can't complete the final step.
Bob
Thank you for the reply. And thank you for doing FOV test for me. I'm still learning.
Apologies to you for not mentioning that I do have a Celestron 6.3 focal reducer. I did the FOV calculations on astronomy.tools and the FOV comes up at 1.22
I'm still not sure why I can't complete the final step.
Bob
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Re: Frames Failed To Solve
Hi Bob,
so, even with the 0.66x reducer, you still end up below the minimum by my calculation - 0.47x0.26 degrees by my calculations, since your effective focal length is still 1300mm or so.
Mind you, it's odd that you seem to be succeeding at the earlier stages and failing at the adjustment. It would be worth watching the 'Plate Solving Status' section while you progress - for good results it should be in the green 'Solved' state for the most recent frame almost all the time. It could be that you are getting a red 'Failed to Solve' most of the time with the odd frame solving. You tend to get past the first two stages like that because it working once at each stage is enough, but at the final stage it needs to work pretty much every frame to be usable.
Feel free to grab a few images from the camera at different stages of the process (press the snapshot button) and share them here - I can then check to see if there is anything obvious wrong beyond the small field of view.
cheers,
Robin
so, even with the 0.66x reducer, you still end up below the minimum by my calculation - 0.47x0.26 degrees by my calculations, since your effective focal length is still 1300mm or so.
Mind you, it's odd that you seem to be succeeding at the earlier stages and failing at the adjustment. It would be worth watching the 'Plate Solving Status' section while you progress - for good results it should be in the green 'Solved' state for the most recent frame almost all the time. It could be that you are getting a red 'Failed to Solve' most of the time with the odd frame solving. You tend to get past the first two stages like that because it working once at each stage is enough, but at the final stage it needs to work pretty much every frame to be usable.
Feel free to grab a few images from the camera at different stages of the process (press the snapshot button) and share them here - I can then check to see if there is anything obvious wrong beyond the small field of view.
cheers,
Robin
Re: Frames Failed To Solve
Good day, Robin!
Again, thank you for your help with this issue. I do appreciate your time!
I do have a ZWO30mm f/4 Guide Scope I'm going to try tomorrow night. Hoping this will work.
It is odd that I get the first two stages solved and not the last. I will use the ASI585MC and grab some shots for you just to see what's going on. Hopefully they can give you some information that can help.
Enjoy your day, Bob.
Again, thank you for your help with this issue. I do appreciate your time!
I do have a ZWO30mm f/4 Guide Scope I'm going to try tomorrow night. Hoping this will work.
It is odd that I get the first two stages solved and not the last. I will use the ASI585MC and grab some shots for you just to see what's going on. Hopefully they can give you some information that can help.
Enjoy your day, Bob.
Re: Frames Failed To Solve
Hi Robin!
Apologies for not getting back to you sooner. Been busy and the night skies haven't been cooperating.
I finally was able to PA using the ZWO 30mm Guide scope and ASI120mm Min camerai.
I appreciate your time in helping me with the issue I had! Now it's time to enjoy SharpCap and get some images stacked!
Thanks again and be safe,
Bob
Apologies for not getting back to you sooner. Been busy and the night skies haven't been cooperating.
I finally was able to PA using the ZWO 30mm Guide scope and ASI120mm Min camerai.
I appreciate your time in helping me with the issue I had! Now it's time to enjoy SharpCap and get some images stacked!
Thanks again and be safe,
Bob