Simon Coleman, 48, of Spring Road, admitted a spate of offences when he appeared at Southampton Magistrates Court.
Coleman pleaded guilty to making 158 Category A images – the most serious type – between December 5 2021 and September 7 2024.
He also admitted making 100 Category B images of a child between the same dates and possessing a prohibited Category B image on September 8 2021.
The defendant also admitted making 215 Category C images of a child between December 5 2021 and September 7 2024 and distributing two Category C images in September 2024.
He also pleaded guilty to breaching a risk of sexual harm order by failing to provide an iPad for inspection on January 8 2023.
Coleman was bailed to appear at Southampton Crown Court on August 14 2026, when he is due be sentenced.