For this post, I am defining an camera store retailer as a retailer who sells new cameras and related accessories. This is not for production studios, repair only businesses, pawn shops, etc.
Low Volume (single check out lane, less than $380000 in annual gross sales): Shopkeep or Vend. These are good subscription based solutions with affordable monthly subscription costs. Most retailers can set these systems up with minimal assistance or training which saves on up front costs. These POS programs will likely handle 80% of what you want.
Mid Volume (2+ check out lanes, less than $2.5M in annual gross sales, no more than 50 store locations, basic repairs): You are in a position to utilize a POS system than handles some of the unique requirements that camera retailers have like tracking serial numbers, product attributes, and off site sales at events. Here is an example of serial numbers being used in the Cloud Retailer point of sale software: