How faint is TOO faint?

My husband says he can see it but believes we're just seeing an "existing second line" that world be darker if it was positive. I'm just unsure because previous BFNs haven't had a second line at all. I don't use OPKs so my guess is that I ovulated around the 1st April, but I'm not 100% sure if  y body has fully adjusted after stopping birth control in December. Very new to TTC. Thank you in advance for any tweaking / advice x