Hrmm... those 8's are nice and small! And aren't they like waterproof already? Without need of a casing?Unless you have an even older or worse camera that retailed for $100+ originally working or not you can send that Hero 3 into Gopro for a hundred off the Hero 8.
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For stationary or handheld shots I think the S10 should be good enough. You should be able to go into it and tweek the settings enough. Just get something to hold it comfortably in a horizontal position.
Yeah I bought another 1/4 - 20 adapter plate for my Outdoorsman's Micro Pan Head so I could install it on the bottom of a phone holder (my PhoneSkope Lollipop model) so I could mount it in there for the Grip-n-Grin pictures using the Tripod. Figure just rotate the phone around within the holder when need to mount it on the Tripod for that so the PhoneSkope isn't in the way, since it's got two lenses. That way it can get a better picture of the subject during the Grip-n-Grin pic without limiting it to just the one lense that shows thru the hole in the adapter.
Can you post up a link to this external battery and needed cables that you mentioned for the headcam?
For a stationary setup, I was figuring find out best price to feature ratio cam, put on tripod, and maybe have it running straight thru during the primo morning hours. Then if a no-show. Only turn it on as needed rest of day, only if see something. Then just bring enough battery and mem card to support it.