It might be hidden from the subject at that distance, but it's the people near you or walking past who might see it. A camera on a nude beach is almost classed as a deadly weapon by beach users nowadays. Brighton is steeply sloped, so not easy to take photos, unless the subjects stand up. The best day is WNBR day as inhibitions shown on the ride are often discarded on the beach and the sheer number of photographers make it easy!
