The diminishing levels via decay means that the effective limit for using c14 to estimate time is about 50,000 years. After this time, there is little if any c14 left. Subsequent work has shown that the half-life of radiocarbon is actually 5730 ± 40 years, a difference of 3% compared to the Libby half-life.

What are the 2 limits of using carbon-14 in dating the age of objects?

First, the older the object, the less carbon-14 there is to measure. Radiocarbon dating is therefore limited to objects that are younger than 50,000 to 60,000 years or so.