Plate Solve Problem (200mm Lens)

Hello. Tonight I was running some backyard tests on my new 200mm lens, yet I was having a bunch of problems with plate solving. In SGP, I load an image of an object that I render out from WikiSky, and I use plate solving to get the center coordinates for that object in the sequence.

Normally, plate solving works well when using the Center On functions and it is able to solve my fields in a reasonable amount of time. With the 200mm lens, however, it failed every time. I use the local solver for my plate solving in SGP.

Here’s where it gets strange - I switched to my old method (Astrotortilla and BackyardEOS), and used the same settings, and it was successful every time.

The main difference between the two programs seems to be that Astrotortilla allows me to enter in a minimum and maximum scale in arcsec/pixel, and it uses that number for every single plate solve, including what comes from the camera. SGP, however, seems to only have this option when plate solving a file to create an object, not when the camera is used for Center On slewing.

Is there any way, in SGP, to specify either a minimum or maximum, or even an estimate scale, for the Center On slewing that is used for auto centering, similar to the function available when creating a new object for sequencing? It seems to me that the plate solving is failing because it is doing a blind solve rather than benefiting from knowing the image scale coming from the camera.

I hope this made sense…please let me know if I can explain better. Thanks again for your great support on this excellent product!


Certainly, just enter the scale on the camera tab of the Control Panel.


Ok, that’s probably what went wrong. SGP help says that a successful plate solve fills in that info for future reference. Since I didn’t change it prior to running the tests with the 200mm lens, it was likely using the number in there already, which came from using my 714mm telescope. If that is the case, it explains the failure. I will run further tests tomorrow night. Thanks for the quick response!

1 Like

Ah, yes, that would certainly cause the problem. Your best bet is to setup a separate profile for each system.