I like your ideaI feel location is the key. get a place with free parking at night.. even non photog-fans will drop by. There are lots of vehicle groups that are constantly looking for free parking places to hang out at night after work. Free parking is a big draw.
Next will be seating. Free parking coupled with lots of seats even if outdoor seating with fans many will be happy. Just prepare for lousy business during rainy days.
Some of the more successful kopi-places I've been to was "selegie kopitiam" opposite rochor beancurd, now "banquet' food court.. very popular amongst late night chiongsters and impromptu meetups. lots of .. erm.. "free" parking behind. They shifted out cos the rental was raised exorbitantly, from what i learnt.
West coast mac and Kallang mac, LOADS of free parking at night.
Rex at McKenzie rd. Got a big space.. loads of parking lots. Outdoor seating only. I think now closed down cos the lease for the area was up? not too sure on accuracy of that.
To cater mainly to photographers is not quite a viable solution.. Maybe allow photo enthu to submit photos for them to put up and to be changed every fortnight? It could be a good place for pros-to-be to 'exhibit' their stuff without having to pay high rates for an exhibition hall/booth/place.