Hello,
I'm trying to plate solve with my Celestron 14 with a Starizona 0.67 (for the case with a C14) and a QHY168C (APS-C sensor size), but it's failing. I am using ASTAP as the solver with the D50 database. Starizona says that the effective focal length with the reducer is 2365, and using the Astronomy Tools app, it says the FOV is 0.52 x 0.35 degrees. Every once in a while, I get lucky (maybe only twice so far), and I'll get a successful solve, but most of the time it fails.
One theory as to why this might be happening is the quality of my image. To get one that's not too dim, I'll do a 3min exposure. A theory that I have as to why the solver fails is because the image it uses. A raw live image (outside of Livestack) looks horrible mainly because the color balance is way off (it's very green with poor contrast). However, if I do a live stack, I can balance color and the image looks really nice after stretching it as well (which I can still do with the raw live image outside of Livestack). If I'm able to load a color-corrected image from the Livestack image into the plate solver, would that solve the issue?
Perhaps there is a way to adjust the color with the live image outside of Livestack? Come to think of it, I suppose there is by adjusting the gain for each channel, but I'd have to set it back to its original values in order for it to be calibrated with my dark frame. I also want to keep all three gain settings the same so I can preserve the same bit depth for each of the RGB channels.
In the Plate Solving Configuration tab, I have selected "Do not use" for the focal length of the telescope. Perhaps I need to in this case?
Clear skies,
-Gene
Image quality while plate solving with a C14 & Starizona focal reducer
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Re: Image quality while plate solving with a C14 & Starizona focal reducer
Hi Gene
Maybe you already did this, but what happens when you use 100% Gain and 4 seconds for a plate solve?
I'm on 2100mm focal length with also a APS-C sensor (Zwo ASI071MC Pro) and get enough stars for a plate solve with that. This with a 50/50 whitebalance setting.
Also, did you try the build-in SharpCap plate solver SharpSolve? For me it gives fine (and way faster) results compared to ASTAP and/or ASPS.
If you don't have that, update to the latest SharpCap version.
Menno
Maybe you already did this, but what happens when you use 100% Gain and 4 seconds for a plate solve?
I'm on 2100mm focal length with also a APS-C sensor (Zwo ASI071MC Pro) and get enough stars for a plate solve with that. This with a 50/50 whitebalance setting.
Also, did you try the build-in SharpCap plate solver SharpSolve? For me it gives fine (and way faster) results compared to ASTAP and/or ASPS.
If you don't have that, update to the latest SharpCap version.
Menno
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Re: Image quality while plate solving with a C14 & Starizona focal reducer
Hi,
it might be worth turning off the option for SharpCap to use the focal length while testing - it does make plate solving quicker, but can cause it to fail if the entered value is significantly wrong (and sometimes reducers don't give the exact focal length expected). Once you get a plate solve success, you will get the FOV which means you can check the focal length.
I don't think a green background should hurt - the plate solving tool like Astap will be removing the background level as part of the star detection routine anyway.
One good test is to save a problem image using the 'Snapshot' button and then upload it to the online solver at nova.astrometry.net to see if that works - you can also share the link to the uploaded image here so we can take a look and possibly give more targeted advice. I'm with Menno though that a high gain and shorter exposure would be ideal (probably 30s or less, even with such a long focal length).
cheers,
Robin
it might be worth turning off the option for SharpCap to use the focal length while testing - it does make plate solving quicker, but can cause it to fail if the entered value is significantly wrong (and sometimes reducers don't give the exact focal length expected). Once you get a plate solve success, you will get the FOV which means you can check the focal length.
I don't think a green background should hurt - the plate solving tool like Astap will be removing the background level as part of the star detection routine anyway.
One good test is to save a problem image using the 'Snapshot' button and then upload it to the online solver at nova.astrometry.net to see if that works - you can also share the link to the uploaded image here so we can take a look and possibly give more targeted advice. I'm with Menno though that a high gain and shorter exposure would be ideal (probably 30s or less, even with such a long focal length).
cheers,
Robin
Re: Image quality while plate solving with a C14 & Starizona focal reducer
Gene
What model of C14 is it?
Dave
What model of C14 is it?
Dave
Re: Image quality while plate solving with a C14 & Starizona focal reducer
Thanks everyone!
These are all useful comments. I tried again last evening and it finally seemed to work. What I did was pay attention closer attention to the display histogram pane on the sidebar to make sure that the color balance was reasonable and then I had it automatically adjust the stretch. When I did so, ASTAP found a solution within seconds and it worked. I tried it twice and it worked.
To answer Dave's question, my C14 is a really old one from the late 80's, not Fastar compatible.
Robin, I did have the "Do not use" option selected in the PlateSolve setup tab. Now that I have a few images, I will load it up to Astrometry.net so I can get a more accurate value for the true focal length.
Last evening, I was able to get a solve with 30s exposures. Menno has the same sensor as I do however (as I'm sure that Robin is fully aware), QHY's gain settings are quite different than ASI's so unfortunately, it's not easy to translate a what a gain setting of 100 means or 50/50 white balance is because my gain setting only goes from 1-14 for each of the RGB channels, and I don't see a white balance anywhere. There also is a digital gain which goes from 1-14 as well which helps brighten the image. I had a hard time understanding what this does, but after a lot of discussion from Robin (Thanks!), I now know that this is meant to brighten the image for short exposures. The next time that I am out, I will upload one of my images.
So far so good, but I will certainly try everyone's suggestions to see if I can shorten up the exposure. Boy, when it works, it's awesome! The good news is that my mount seems to work really well and I don't have to do this that often as long as I have an accurate polar alignment which also works very well with SharpCap.
-Gene
These are all useful comments. I tried again last evening and it finally seemed to work. What I did was pay attention closer attention to the display histogram pane on the sidebar to make sure that the color balance was reasonable and then I had it automatically adjust the stretch. When I did so, ASTAP found a solution within seconds and it worked. I tried it twice and it worked.
To answer Dave's question, my C14 is a really old one from the late 80's, not Fastar compatible.
Robin, I did have the "Do not use" option selected in the PlateSolve setup tab. Now that I have a few images, I will load it up to Astrometry.net so I can get a more accurate value for the true focal length.
Last evening, I was able to get a solve with 30s exposures. Menno has the same sensor as I do however (as I'm sure that Robin is fully aware), QHY's gain settings are quite different than ASI's so unfortunately, it's not easy to translate a what a gain setting of 100 means or 50/50 white balance is because my gain setting only goes from 1-14 for each of the RGB channels, and I don't see a white balance anywhere. There also is a digital gain which goes from 1-14 as well which helps brighten the image. I had a hard time understanding what this does, but after a lot of discussion from Robin (Thanks!), I now know that this is meant to brighten the image for short exposures. The next time that I am out, I will upload one of my images.
So far so good, but I will certainly try everyone's suggestions to see if I can shorten up the exposure. Boy, when it works, it's awesome! The good news is that my mount seems to work really well and I don't have to do this that often as long as I have an accurate polar alignment which also works very well with SharpCap.
-Gene
Re: Image quality while plate solving with a C14 & Starizona focal reducer
Gene
You could try solving with a focal length of 2620 (3910 x 0.67).
Dave
You could try solving with a focal length of 2620 (3910 x 0.67).
Dave
Re: Image quality while plate solving with a C14 & Starizona focal reducer
I had another observing session last night, and I think I've found an issue with the mount. My mount is a Takahashi which uses the Temma2 controller. I use the ASCOM driver for it and it works just fine. My planetarium interface is Cartes du Ciel, and of course, Phd2 for guiding.
The issue that I notice is when I connect the mount via the Scope Control sub window, it the coordinates for RA and Dec are zeros. I can control the mount with the cardinal control buttons, so I know that SharpCap is communicating with the mount. If I try a platesolve, it fails. (-Asside: when I try the test plate solve in the platesolve tab, it works and almost instantaneously reports the coordinates.) Both PhD2 and Cartes du Ciel are connected to the mount, and I connect Sharpcap last. What I have to do is fumble around a bit by connecting/disconnecting the mount until I see the RA and Dec. coordinates in the Scope Control window, and then the platesolving works. I do not have the "connect hardware automatically option enabled" and click the "Connect" button in the Scope Control button to connect to the mount. This is because I don't always have the mount connected when I use Sharpcap.
Am I missing something in the initialization to get the coordinates from the mount to load properly?
-Gene
The issue that I notice is when I connect the mount via the Scope Control sub window, it the coordinates for RA and Dec are zeros. I can control the mount with the cardinal control buttons, so I know that SharpCap is communicating with the mount. If I try a platesolve, it fails. (-Asside: when I try the test plate solve in the platesolve tab, it works and almost instantaneously reports the coordinates.) Both PhD2 and Cartes du Ciel are connected to the mount, and I connect Sharpcap last. What I have to do is fumble around a bit by connecting/disconnecting the mount until I see the RA and Dec. coordinates in the Scope Control window, and then the platesolving works. I do not have the "connect hardware automatically option enabled" and click the "Connect" button in the Scope Control button to connect to the mount. This is because I don't always have the mount connected when I use Sharpcap.
Am I missing something in the initialization to get the coordinates from the mount to load properly?
-Gene
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Re: Image quality while plate solving with a C14 & Starizona focal reducer
Hi,
I think a good test would be to try only connecting SharpCap to the mount and see if that works consistently. If it does then that would suggest that sharing the mount driver between different applications could be the cause of the problems with zero readouts for RA and Dec. In that case, I would suggest using the ASCOM 'Device Hub Telescope' driver in all your applications and set up the device hub to talk to the real ASCOM driver for your mount. The device hub is designed to support sharing between applications in cases where the true ASCOM driver doesn't support sharing (or has problems with sharing).
Going back to the plate solve issue, an incorrect RA/Dec readout from the mount will definitely cause problems, since SharpCap by default searches within 15 degrees of the mount co-ordinates to speed up solving.
cheers,
Robin
I think a good test would be to try only connecting SharpCap to the mount and see if that works consistently. If it does then that would suggest that sharing the mount driver between different applications could be the cause of the problems with zero readouts for RA and Dec. In that case, I would suggest using the ASCOM 'Device Hub Telescope' driver in all your applications and set up the device hub to talk to the real ASCOM driver for your mount. The device hub is designed to support sharing between applications in cases where the true ASCOM driver doesn't support sharing (or has problems with sharing).
Going back to the plate solve issue, an incorrect RA/Dec readout from the mount will definitely cause problems, since SharpCap by default searches within 15 degrees of the mount co-ordinates to speed up solving.
cheers,
Robin
Re: Image quality while plate solving with a C14 & Starizona focal reducer
Thanks Robin,
I tried the ASCOM Device Hub driver and it all seems to work now. I'm able to get the platesolving to work now with 15sec. exposures with the green background. It looks like the main issue all along happened to be this one. It kind of made sense once I noticed that the platesolving would work when I tested it in the PlateSove setup menu.
-Gene
I tried the ASCOM Device Hub driver and it all seems to work now. I'm able to get the platesolving to work now with 15sec. exposures with the green background. It looks like the main issue all along happened to be this one. It kind of made sense once I noticed that the platesolving would work when I tested it in the PlateSove setup menu.
-Gene