You generally don’t need a special DSLR with a built-in barcode scanner. A practical untethered workflow is to use almost any camera plus a separate barcode scanner.

The simplest approach is to keep the camera clock synchronized with the scanner’s clock (or logging time). Scan the barcode just before or after each subject/session, then later match scan timestamps to photo timestamps and use a script or existing software to write the barcode into filenames or metadata.

A phone app can work as the scanner, but a dedicated handheld scanner may be faster and easier to keep with the camera. This gives immediate confirmation that the code was read successfully.

If you want a more custom automated system, a small computer such as a Raspberry Pi can be connected to a barcode reader and camera. It can log the barcode, pull images from the camera, and batch-apply metadata based on scan order or time.

So: no specific camera is required. The key is a reliable barcode-scanning device, accurate time sync, and post-processing or custom scripting to merge the barcode data into the images.