I figured out that camera lenses are using 16bit addressing system and SPI protocol. We need to send and retrieve 16bit data from lenses. And then we need to decode that data stream to human readable. Unfortunately, the data that can be sent and retrieve to lenses is different for every model of the same lens manufacturer. Camera manufacturers include all the information(focus length, aperture range) in their firmware through camera lens ID code. Either we need to get data stream information and observe that by oscilloscope and function generator and translate that to lens information but we've to perform that for every lens model on the planet or else we can ask the camera manufacturers about their own SPI system (what bytes for what).

Clarify me whether the communication system between cameras( of different manufacturers) and lens is same or do we need to implement different communication protocols for different camera manufacturers? Do all lens systems from various manufacturers follow same communication protocol to their cameras?

Hi,
Is it something like this (http://www.ixbt.com/digimage/canonautosonyl.shtml) that you want to implement ??