Damselflies come in many forms, but, unlike birds, many are difficult, if not impossible, to identify positively with binoculars. They are just too small. Close examination of terminal parts is probably the most reliable identification method for damsels. This typically requires capturing the creature, at least temporarily. Luckily, many species can be identified by macro-features, visible in good photos or viewable with a pair of close-focusing binoculars, without the need for nets.
Today's top photo shows a male Variable Dancer (Argia fumipennis), the only violet damselfly in New England. The photo below shows a male (violet, left) and female (brown, right) in tandem. At just over one inch long, these creatures are easy to miss.