Cheers prawny,
But I’m thinking far older / cheaper than an S2 (my current phone is an S2 though) I’ve got an old (but quite robust) Nokia that’ll do 640 x 480 @ 30fps apparently, should be just about “adequate” in clearish daylight conditions.
I’d use one of those stick on fisheye/Wide angle/Macro jobbies for ~£6-10 from fleabay to adjust the narrow view angle view angle, “Mounting & weather proofing” would be achieved with gaffa tape, zip ties, and maybe some araldite, most likely positioned somewhere on to my rucksack straps…
The phone can be treated as a pretty much sacrificial item it has minimal value, I’ve got a few options for phones as there’s a bag of mine / my missus phones from the last decade or so sat in a cupboard,
But I’m talking proper “Lo-Fi” here… budget would be £15 max or else these’s little point in the idea…