This is a bit complicated. I looked into it.
The card has a few partitions on it... it has a couple of Linux “ext4” partitions, a large FAT32 partition, and I think it had a swap partition.
Regardless, it’s the FAT32 partition where the images are stored. While you normally can tell the OS to “grow” a partition, the limit is that it uses a FAT32 partition; FAT32 has a maximum size of 32GB. This means that even if you cloned the card to a 64GB or 128GB card, you can’t “grow” the FAT32 partition beyond 32GB. Also, I think I noticed the ext4 partitions are placed *after* the FAT32 partition (meaning things would need to get moved around because partitions have to be contiguous. There are filesystems that can span multiple devices and partitions... but these aren’t filesystem types natively supported by PCs or Macs (without installing new software to support them)... so they aren’t worth pursuing.
For those familiar with how to create and manage partitions in Linux, you probably can manually create a card with the correct size ext4 partitions, but create an exFAT partition to replace the FAT32 partition ... then carefully copy all the files from the source partitions to the destination partitions.
But there is also the caveat of whether or not the Raspbian Linux has the exFAT filesystem driver installed.... otherwise it won’t be able to deal with the exFAT partition. This would require that you can modify the OS (have ‘root’ permission) and the device is really designed as a turn-key appliance (you’re not supposed to need to log into the OS to do maintenance).
But there is another question: Do you really *need* a larger card?
My first night out of really putting this thing through it’s paces involved shooting about 2 hours worth of data using an ASI128MC-Pro. The is a full-frame camera with a resolution of about 6000x4000. I think I ended up with 26 lights, 10 darks, 20 bias, and 20 flats ... and all that used about 4GB of space.
If I were to imagine shooting for two or three times as many hours in a night, I think it would probably fill about half of the available space.
If I were to shoot night after night (on a trip away from home and without a computer) then it could be a problem... but just cloning out additional cards would fix the problem (which isn’t a bad idea anyway since memory cards fail from time to time and this would offer lots of redundancy).
I’m not against larger cards... just offering my thoughts on what I found when I inspected the partition layout of the existing card. Simply cloning to a larger card and hoping to grow the partition wont be enough.
