How does tenant Based Section 8 work for apartment owners?

[Alfred Harris]

I'm thinking of purchasing a low income apartment community. I know it has a number of tenants on section 8 also. I also know the process to obtain and loss the voucher. What I don't know is how the pay out from government works. Is it percentage based? Is it a cap on how much they give? I mean wouldn't a landlord want section 8 tenant every unit, knowing he will get a check on the 1st from the government. Does anyone about property based section 8?