Having shot both in-housing Alex Mustard's Magic Filters, and many a wet-mount lens / filters.
Ummmmmm, it's danggg hard to take off the filter while underwater if it's in the housing, tends to make the camera wet.
So if you go from shooting shallow ambient lighting, to deeper "gotta have a filter"..........you're screwed with an in-housing gel.
I like to shoot my Giant Stride or back roll entry, with an in-housing filter you aren't going to be able to do that..........blown out reds..............
I like to take a filter on/off during the dive............and the water between a housing and external filter/lens makes little or zero difference.
Ummmmmm, it's danggg hard to take off the filter while underwater if it's in the housing, tends to make the camera wet.
So if you go from shooting shallow ambient lighting, to deeper "gotta have a filter"..........you're screwed with an in-housing gel.
I like to shoot my Giant Stride or back roll entry, with an in-housing filter you aren't going to be able to do that..........blown out reds..............
I like to take a filter on/off during the dive............and the water between a housing and external filter/lens makes little or zero difference.