I have managed to successfully setup plate solving to work using the astrometry.net offline solver (on Mac OS).

The solved images have the correct position, but the FOV shown is exactly (1/4 x 1/4) of the correct value.

If I set the search size to automatically adjust in the settings, it always fails to solve the second image, as values far too small are automatically inputted!

If I use the online solver within Ekos it also gives the wrong FOV, but the website version of astrometry reports the correct value.

I have checked that the focal length and aperture are set correctly in Ekos, although I don’t see how this could make a difference, as surely the FOV is exclusively determined by the image itself.

Is there anything I’m missing/doing wrong?

Thanks!

1. What's the telescope focal length?
2. What's the camera pixel size in microns?
3. What camera?
4. Are you using binning?
5. Logs with Alignment option checked?

Dear knro,

The focal length is 430mm, aperture of 73mm.
The camera is an ASI 294MC Pro with a pixel size of 4.63μm

All these values appear correctly in the settings.

I tried with multiple binning settings and all produced the same result, I've currently set it to 4x4.

I enabled logging and the logs show the correct FOV when the image is solved, but the FOV reported in the plate solving tab of Ekos and the Kstars CCD overlay are both giving a value (1/4 * 1/4 of that size).

Thanks for the quick reply!

Don't forget Focal Reducers. So we are supposed to calculate it ourselves? (I know I'm being lazy)

But even the length (depth) of the Focuser will affect FOV a tiny bit.

We used to put 0' x 0' in and it would be calculated. I did notice the new ASTAP would give a better or at least closer than astrometry. Astrometry wouldn't take into account the Focual Reducer I use.

Do you have a guide scope? If yes what's the focal length? If you switch between primary and guide scopes in alignment, does this change the FOV value?

(Assuming you are talking to me... which is fine if you're not)
I do. I'll have to check in a couple of days about the switch. I don't have my rig setup due to past bad weather and I have to work tonight (dang it and the weather is beautiful too)

Guide Scope is 190mm and camera is a ZWO 120MC
Main Scope a Celestron 8SE is 2032 mm. But with a 6.3 Focal Reducer. The Camera is a ZMO 1600 Mono. A Filter wheel adds some more space too.

So what I've go with is: FOV: 43.1' x 32.6'
Guide scope FOV: 90.4' x 67.8'

I also have a guide scope, focal length of 240mm and an aperture of 60mm.

When I switch from primary to guide scope it does indeed change the FOV value, but still not to the correct FOV