Early Minox cameras from Minox II to earlier Minox B were equipped with a four-element, three-group Complan lens designed by ex-Leica lens designer Arthur Seibert. The Complan lens has a curved film plane, hence in these cameras the negative must be held in an arc to improve the edge-to-edge sharpness of the image. The Minox enlarger also holds the negative in this same curve. Later models, beginning with late model Minox B, to the current model TLX, using the 15 mm f/3.5 four-element, three-group flat-field Minox lens, and the negative was held flat.
The early Minox cameras from Riga to Minox B and BL, were equipped with a mechanical shutter, while later model Minox cameras have an electromagnetic shutter. When closed, the viewfinder and lens windows are protected. Complan lens and Minox lens are unit focusing lens, focusing from 8 inches (20cm) to infinity through precision gear linked to a focusing dial on top of the camera. All Minox cameras, except the EC, have a parallax correction viewfinder: when the focusing dial moves, the viewfinder moves in tandem to correct for parallax.
From the Riga to Minox B, the film counter counts up to 50, while from Minox BL, C, to CLX, the film counter counts down from 36/30/15. For mechanical Minox 8x11 cameras, a separate shutter speed dial sets the shutter speed from 1/2 to 1/1000 second, plus B and T (BL has no T). For electromagnetic shutter cameras, the shutter dial starts with 1/15 sec, and ends with 1/1000 (Minox C), or starts with 1/30 and ends with 1/2000 (Minox LX/TLX/CLX); the electromagnetic Minox camera also has an 'A' setting for automatic exposure, controlled by the built in exposure meter.
Above the viewfinder is a filter bar used to slide a green or an orange filter in front of the lens; starting with the BL, there is only a Neutral Density filter.
For Riga Minox to Minox B, the film advances each time the camera is closed, regardless of whether a picture is taken or not. Opening the camera causes the pressure plate to press the film into a concave or flat (depending on the model) surface to stiffen thin emulsions for better clarity. When the camera is closed, the pressure plate moves back from the film plane, thus allowing the film strip to move freely to advance to the next frame. From Minox BL onward, the camera is equipped with a "freewheeling" mechanism, such that the film advances one frame only when a picture is taken, otherwise, closing the camera does not advance a frame.
Minox BL uses a PX625 button cell to power the CdS exposure meter; Minox C, LX, EC, used a 5.6v PX27 mercury battery to power the exposure meter and electromagnetic shutter. TLX, CLX, ECX use four 1.5v 386 silver oxide button cell in an adapter; this adapter combo can also be used to replaced the discontinued 5.6v PX27 battery for Minox C, LX and EC.