I'm not sure if this question My minolta rokkor? Camera has ASA settings ranging from 25, 50, 100, 200, 400, some dots in between each number, now what setting should I put it on? I don't know if it has any relation to the film that I use but if it does my film is the tri-x 400 film 400TX black and white. what is f=38mm? and 1:2.8 means what? BTW the ASA, F=38mm, and 1:2.8 are all around the lens I also have a olympia camera that I found(still testing if it works at all not sure yet will have to develop the film to see it has similiar thing like f=1:4.5 and 50mm motor drive? and aspherical lens 16,15, 8, 6.34.5 what do these things mean I'm puzzled. Sorry for all the questions! Any help would be appreciated!