Sharpcap platesolver settings

[IDM]

I have been using Sharpcap with ASTAP platesolver for about a year with general success. the issue I have is that sometimes it will solve in seconds and sometimes it takes minutes.

More recently I have been experimenting with different refractors with different focal lengths and am having very poor results with long times spent with the platesolver thinking followed by messages like "failed to solve", "no stars" or "too many stars".

 What are the best settings? do people input their focal length into the plate solver tab? What about the 8 bit format? Any thoughts on the best solutions?

Thanks

Ian

[Cosmic Geoff]

You have to enter the focal length into the settings. Also get a sharp focus and make sure the exposure is long enough to get enough stars. If it won't solve, nudging the telescope to a different position may work. With a 102mm f5 refractor the platesolving should work very well.

[StevieDvd]

Whn platesolving the focal length of the scope is used to refine the field of view and the index files to use in the plate solve search. If the image you pass to plate solve is captured using a different field of view than that calculated using the wrong focal length it can mean the image is not solved. If the focal length is omitted the software can do a blind solve but that takes a lot longer.

In the Asiair app the focal lnegth can be entered or set at zero, then the app works out the focal length for you. Not sure if SharpCap has a similar option, but if you can enter the detail it would be best to change it when you use a different scope.

 

[IDM]

11 minutes ago, Cosmic Geoff said:

You have to enter the focal length into the settings. Also get a sharp focus and make sure the exposure is long enough to get enough stars. If it won't solve, nudging the telescope to a different position may work. With a 102mm f5 refractor the platesolving should work very well.

 

11 minutes ago, StevieDvd said:

Whn platesolving the focal length of the scope is used to refine the field of view and the index files to use in the plate solve search. If the image you pass to plate solve is captured using a different field of view than that calculated using the wrong focal length it can mean the image is not solved. If the focal length is omitted the software can do a blind solve but that takes a lot longer.

Thanks both. Last night I tried with (inputting the focal length) and without (omitting the focal length) and both were equally poor. What was frustrating was that several times when I tried short exposure times with very little in the way of stars on the screen the platesolver reported; more than 540 stars unable to solve, try reducing exposure.

I did wonder about focus, but had used Sharpcap's multi star focus assistant to get focus pretty good. Luckily I had two scope out so at least while I did battle with one the other had very happily solved and was taking decent photos until the inevitable clouds rolled in!!

Are there any other things I should try?

[AstroMuni]

21 hours ago, IDM said:

What was frustrating was that several times when I tried short exposure times with very little in the way of stars on the screen the platesolver reported; more than 540 stars unable to solve, try reducing exposure.

What camera do you have and what are the exposure, gain & binning settings?

[IDM]

7 hours ago, AstroMuni said:

What camera do you have and what are the exposure, gain & binning settings?

Great question. With regard to settings I really should be more systematic and write these things down. I  can say I have tried increasing the gain and or increasing exposure with really mixed success.  I have tried 2 camera a QHY183C and a Zwo 294MC. Binning so far has always been at 1. I had wondered about 2x binning, do you think it might help?

Thanks,

Ian 

[AstroMuni]

19 hours ago, IDM said:

Great question. With regard to settings I really should be more systematic and write these things down. I  can say I have tried increasing the gain and or increasing exposure with really mixed success.  I have tried 2 camera a QHY183C and a Zwo 294MC. Binning so far has always been at 1. I had wondered about 2x binning, do you think it might help?

Binning helps when platesolving and a lot of software already do that before sending the image to ASTAP. Check your settings, it maybe called downsample image. Also check if you have the correct offline files downloaded for the platesolver. Try using astrometry.net instead of ASTAP and see if it platesolves. If the issue is only with ASTAP then the author @han59 is here in the forum. Good luck.

EDIT: Read this post https://www.cloudynights.com/topic/726834-speed-vs-resolution-vs-accuracy-in-plate-solving-what-the-the-tradeoffs/

Edited March 17, 2023 by AstroMuni

[IDM]

 

 

1 hour ago, AstroMuni said:

Binning helps when platesolving and a lot of software already do that before sending the image to ASTAP. Check your settings, it maybe called downsample image. Also check if you have the correct offline files downloaded for the platesolver. Try using astrometry.net instead of ASTAP and see if it platesolves. If the issue is only with ASTAP then the author @han59 is here in the forum. Good luck.

Will certainly try that. Unfortunately I am busy for the next couple of weeks so it may be a while before I can run more tests.

Thanks

Ian