Good. Auto is only intended to find the image scale. It will just go trough all image scales. Once you know the image height, adapt focal length accordingly.
There was a problem with image scale of the guide scope focal length which was fixed two weeks ago. I don't know which version this is:
>> knro wrote:
>>I believe I found the issue. INDI::CCD was always using the primary focal length when calculating CDELT1,2. It's now fixed in GIT.
>>It's not set in the driver, it's calculated. So they need to use INDI Nightly or update from GIT. Since this is a major bug, I will also publish it to the stable channel.
Normally you don't have to worry about the values once they are set correctly. If you load an image in ASTAP, you can read the image dimensions in degrees in the viewer statusbar or in the alignment tab the image height as calculated from the header info. So below as indicated 1.32 degrees. You can overwrite this value (fro solving) by entering a manual value there. This is also handy if you try to solve a jpeg or raw file. This value is stored (save settings or by a solve) until new info is read from the header or command line overrides.
If you select in ASTAP temporary the external local Astrometry.net solver, there is a small calculator included intended for Astrometry.net commandline but could be used to check the values. In the example below, I typed a focal length of 580 mm and pixel size of 5 micrometer resulting in an pixel scale of 1.78" and image dimensions 1.15 x0.869 degrees. The correct pixel size should have been 7.8 micrometer and then the image height will match with the header value above of 1.32 degrees. The calculator values or only used for Astrometry.net command line not for the internal solver.
Han
The image scale should be correct within 5% for best performance but offsets of 30 or 40% could still produce a valid solution.