This camera, like many others of the era, was designed to use the despised "LVS" settings, wherein one sets the EV (Exposure Value) based on a number from EV 1.5 to 17. When the EV is set, one merely has to rotate the aperture/speed rings at the front of the lens to adjust for either the speed or aperture desired, and any setting along that ring will (should) produce the correct exposure as well. Unlike some cameras of this time, the aperture and speed rings are not coupled to each other, you can rotate them independently. For example, if your internal meter indicates an EV of "10," and you want a shutter speed of 1/30th of a second, you would turn the shutter speed to 30 and the aperture setting to 5.6. This would show you the number '10' in the window marked 'EV' on the lens barrel. If you then grasp both the aperture and the speed rings together and move them to the right one click, you have a shutter speed of 1/60th of a second and an aperture of f4, but you still have the EV value of 10, so in theory, your exposure is the same. Get it?