"Translucent Mirror and DSLR Camera" Sony官方可是分得很清楚,Alpha系統有兩種---SLT與DSLR, Alpha 33/55絕對不是隸屬於DSLR的分類
而你的文獻是維基,而我猜應該是這句話--- "A single-lens reflex (SLR) camera is a camera that typically uses a semi-automatic moving mirror system (hence the name "reflex", from the mirror's reflection)"