This may seem like a math question - I suppose it is, about "order of operations".
Example: I have a GH4, which is a 2x crop factor on a lens. If I have a 2x anamorphic lens, the horizontal FOV is essentially the same as if I was using a full-frame sensor (and I do understand vertical FOV is still at 2x crop factor)
Now let's complicate things. Using a S35 camera (pick one - Canon 7D MKII, Ursa Mini, whatever). Crop factor is 1.6. Shooting in 16:9 with a 1.3 anamorphic lens (such as a Hawk VLite). How does one calculate the horizontal FOV on that one? Is it as simple as mutiplying by 1.6, then dividing by 1.3? So - 50mm lens becomes 62mm equiv on the horizontal FOV? (50, multiplied by crop factor, then divided by anamorphic factor).
Some days I wonder about shooting digitally and spherically in 4:3 and then letterboxing in post . . . or 16:9 (or 1.9:1 when it's available) and doing the same. I know, loss of pixels, it's preferred to not be lost.