Sigma 30mm vs Zeiss 24mm

The Zeiss is a great lens, and a lot have to do with its particular focal length, to achieve 35mm focal length there aren't many choices for a fast lens. I came to nex because the nex7 +24mm zeiss would still be cheaper than a nikon FF with 35mm lens or a DX body with the 24mm lens. I don't know how big is your house, but if you want to shoot kids running around, you either have to pan wildly with a 75mm equivalent or just snap and then crop with the 35mm equivalent. With indoor kids picture, it is more so with capturing the moment rather than have them sit and pose, the portrait setting mentioned by the OP should be interpreted this way.

May be you don't notice the significant difference, but i think many who put out for the zeiss never regretted it, it's like i can't tell you how much better something tastes, its all personal, and the general public seems to agree zeiss is a better taste dish, that's just a fact, money wise its a different question, but indoor video i'd say goodluck with the 55-210, i would also just stick with the zeiss, for two reasons, 1st, it is wide so i can just leave the camera recording without framing every so often, then it is the wide aperture to lower the iso. set it up closer to the stage if you need to fill the frame, a steady video is much more enjoyable than shaky zoom in and outs. If you wanted zooming in and panning and all just take a 300 dollar came corder, would probably beat all dslr for that purpose.

the zeiss is worth it, if your shooting style demands it.