Yeh, I basic question.. but I was comparing Canon, Sony, Panasonic, Zeiss and Sigma lenses... and Panasonic and Sigma tend to be much better priced. 

The panasonic lenses have the disadvantage of being m4/3.. but the Sigma ones are good. 

Are they inferior in terms of quality ?

Thanks

I didn't find the right solution from the Internet.

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