"Cryptographic hash functions with output size of n bits usually have a collision resistance security level n/2 and preimage resistance level n." Depending on

"Cryptographic hash functions with output size of n bits usually have a collision resistance security level n/2 and preimage resistance level n." Depending on what you're doing, "SHA-512/128" could have a 128-bit security level. But I guess it's safer to assume n/2 when making a general recommendation.