Sella174 said:
Now (in 1987) the FD system is dropped and replaced with the incompatible EF system.
They did it before, so they can do it again.
But why did they do it?
EF stands for Electronic Focus. It was designed as a FF mount for FILM cameras that would allow electronic communication between the body and the lenses. They had two ways to go.... they could keep all the smarts in the body and use wires to control the motors and read the switches, or they could put some intelligence in the lens and use data communications to control the lens.
With data communications, they had a more flexible system.... they could add motors and switches and keep the interface the same... in other words, it was future-proofed.
The future hit. Digital cameras appeared. There were 1.6X crop, 1.3X crop, and FF. They all kept the same lens mount and there were ZERO changes needed to the EF standard. You can take one of those 1987 lenses and plop it onto your brand new 7D2, a 1DX, a c-500, a 1D-C, any rebel, or with an adaptor, onto an EOS-M. That is what happens with good design....
Would they ever change the design? Of course! It has already happened. To get into the low-cost market that represents the vast bulk of their sales, they created the EF-S mount.... electronically IDENTICAL to the EF mount and even using the same image circle so that you could use the existing EF lenses. Then they did the same thing again and created the EOS-M mount.... still electronically identical, but with shorter flange distances and a smaller mount circle so that they could produce tiny lenses for the mirrorless crop market, yet with an adaptor you can still use any of the EF or EF-S lenses on it.
Remember the direction things are moving in... Canon started with an EF lens mount and ONLY FF lenses.... then they added EF-S and smaller crop lenses.... then they added EOS-M and even smaller mirorrless lenses...
Yes, the pro's use FF, but it is crop that keeps the factory lights on and mirrorless that is the hope for the future. Never forget that we are the minority and in the grand scheme of things it is the low end cameras bought by soccer moms and proud fathers that are what truly matters....