Hi all,

I'm using INDI Library 1.8.5 ; Kstars 3.4.2 ; Source: PPA ; Kernel/Arch : 5.4.0-40-generic #44-Ubuntu SMP Tue Jun 23 00:01:04 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux.

My mosaics that are 1W x 2H have correct overlap, however my 2W x 1H have more overlap - about 30% instead of 5%.
The maths seems to check out OK when looking at the calculated RA/DEC for the panels, but there is a big overlap for some reason.

This can be recreated using the simulator CCD.
I created an example using NGC5139, simulator CCD (1280x1024, 5.2um pixel) with a 480mm FL scope. FOV is 47.67' x 38.14'.
For the example I set a 2Wx1H mosaic with zero overlap, I expect difference between the panels to be 47.67', the width of the FOV.
The tool created 2 jobs:
(1) RA 13h 28m 20.77s DEC -47° 28" 39.59'
(2) RA 13h 25m 10.09s DEC -47° 28" 39.59'
The difference in RA is 3m 10.68s which is 47.67 arcmin, which is what I expected.
There is no difference in DEC, also as expected.

However, in real world use with my Canon DSLR and also evident here using the simulator CCD dimensions and viewing the RA/DEC for each panel in Stellarium, there is a big overlap between panels.