Thanks for the detailed response.
As I understand it, the "Canon DSLR" driver is just a wrapper for the gphoto driver, and judging from the code you pointed to, even though I have configured the setting to capture native frames, when StellarSolver invokes the capture it's taking the FITS pathway (the /tmp file is only generated when FITS is selected for transport). I'm using the internal solver, so in principle it should just be receiving the raw image buffer. I will see if I can dig more to figure out why the wrong setting is used by the driver.

My device is armv7l which is 32 bit. I don't think I'm getting close to 4GB of allocated RAM, but I'll disable the parallel load and see if that fixes the issue. I'm a bit confused, though, about why a 32 bit pi would ship with 8GB of RAM on board- does the limit only apply to the address space of individual processes?

Thanks again, will follow up shortly.

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