The red lever used to select the flash modes: Bulb (M position) and Electronic (A position). It also serves to activate the Self-Timer (V position).
Originally Posted by williamness
The right lever is used to select the shutter speed. To use it you have to move and hold out the left lever.
The left lever is used to select the aperture. Also be used to select the EV numbers.
On the outside of the ring around the lens are different inscriptions: apertures, speed index and flash modes / self-timer.
If you are willing to use the translator, I leave the link where I wrote a small article in a forum in my country: http://www.formatomedio.eu/index.php?topic=6909.0
Regards & Sorry for the traslation.