OM System RM-WR2 Wireless Remote Control Release

Any exposure past a second or two is compromised by the hand that pressed the shutter, and the mirrorless answer is a remote. The RM-WR2 connects over Bluetooth, so there is no cable to snag on a tripod leg in the dark, and it carries several function buttons rather than only a shutter.

It is weather-resistant, which matters because the pictures that need a remote - long exposures, astro, waterfalls - are usually taken in conditions you would not leave a bare electronic accessory in. Supported on the OM-1, OM-1 Mark II, OM-5, OM-3 and TG-7.