Usually I capture images in native format (.cr2). In that case, my files are 5616 x 3744 pixels, which correspond to the maximul resolution of my camera.
However, I also captures a couple of .fits files, and just realised that some of my fits files have slightly different resolution (4365 x 2910). I'm unsure why. I'm testing now INDI with just gPhoto driver, captured two images, one fit and one raw, and both of them have the same resolution, 5616 x 3744.
On the INDI gPhoto control panel - Image Settings tab, I have the correct Width and Height, while Top and Left are both 0. On the Image Info files, same Width and Height, Pixel X, Y and size is 8.20um, bits per pixel is 8 (I tried to set it to 14, which is the correct number, but it doesn't want to change). Note that on the Image Info tab, I sometimes find a different value for Width and Height: 5634 x 3753, which is above my camera's max resolution.
Also, when I open one of my .cr2 files in PixInsight, it tells me this:
Thumb size: 5616 x 3744
Full size: 5792 x 3804
Image size: 5634 x 3753
Output size: 5634 x 3753
Note that apart from Thumb size, all those values are above my camera's max resolution.
I'm trying again at the observatory tonight, so I'm gonna keep a close look at my files resolutions.