I went looking for examples and searched 80A filter and found very little on the main sub. So here is Velvia 100 with an 80A filter including a comparison at the end.
Castell #80A Blue Planetary Filter 30% Transmission
Filter 80A for night street photos? | I Shoot Film | Flickr
Choosing a Color/Planetary Filter
Hoya 80A Filter (Choose)
Cokin P Series P020 Blue 80A Filter – Cambrian Photography
Tiffen 52mm 80A Color Conversion Filter 5280A B&H Photo Video
Wratten 80A Filter, M55, multi-coated, metal mount - WITTNER FILM
Bresser | EXPLORE SCIENTIFIC Filter 2" Blue No.80A | Expand Your Horizon
Tiffen 4 x 5.65" 80A Color Conversion Filter 4565080A B&H Photo