Sony A7

When Sony released the original A7 in 2013, it proved that full-frame sensors didn't need mirror boxes or pentaprisms. At $1,700 it was the cheapest full-frame interchangeable-lens camera ever made, and it was smaller than most APS-C DSLRs. Canon and Nikon initially dismissed mirrorless as a gimmick. Five years later, both scrambled to release their own mirrorless systems. By 2025, DSLR production had effectively ceased. The A7 killed the mirror.