Although I'm not familiar with the specific code, I suspect that the option for saving to the camera just enables the default storage attributes that you have defined by the camera, that is, you're saving as Nikon NEF which is the preferred way of saving the raw data on your D3200. I don't expect the driver lets you override the saving format.

One way of speeding things up considerably is to either boot from an SSD or have an attached SSD on your RPi for storing your images (which you'd keep as .fits, to preserve the capture info.

Cheers

Read More...