Minolta SRT101 (b) 1966-1981
35mm SLR camera with thru-the-lens exposure meter. Standard lens is MC Rokkor PF 55mm F/1.7 (or 58mm F 1.4) 6 elements in 5 groups. The lens is equipped with a meter coupler. ROKKOR-PF = 6 lens elements in 5 lens groups
The Minolta SR-T 101 was one of the first cameras to have full aperture TTL metering.There were actually three versions of the SRT101, with slight variations. The first model had the black, finely-milled, shutter speed dial which was replaced with a dial of three rows of large teeth (model 101b) in the last model, (101c) the mirror-lockup option was dropped. Minolta Srt 101 viewfinder has only a central grid scene to help the focusing and this might cause difficulties, specially with shorter and slower lenses. The split image rangefinder was added to the SRT-102 and as an extra feature, it has also an ability to display the chosen aperture through the finder.
The SR-T 101 uses a PX625 (mercury type) cell for the metering system only. With a dead battery, all functions but the meter will continue to work. Here is a link to Cheap And Easy mercury battery replacement. Google will find you more options.
"Since the inception of through-the-lens exposure measuring for single lens reflex cameras, several systems have been developed. Some "spot" read only a very small percent of the total area. Other systems provide an "average reading comprised of independent measurements taken by two cells which are not accurate in high-contrast situations.
In addition to its more accurate exposure meter system, your Minolta SR-T 101 is designed to handle more easily, with greater speed, than other "through-the-lens metering" cameras.