n78nTechnical NotesRead this chapter for information on compatible accessories,cleaning and storing the camera, and what to do if an error mes-sage is displayed or you encounter problems using the camera.At the time of writing, the following accessories were availablefor your camera.Optional AccessoriesLenses 1 mount lensesMountadaptersMount Adapter FT1Powersources• Rechargeable Li-ion Battery EN-EL21 (0 20–21): AdditionalEN-EL21 batteries are available from local retailers and Nikon-authorized service representatives.• Battery Charger MH-28 (0 20): Recharge EN-EL21 batteries.• Power Connector EP-5D, AC Adapter EH-5b: These accessories can beused to power the camera for extended periods (EH-5a andEH-5 AC adapters can also be used). An EP-5D power connectoris required to connect the camera to the EH-5b, EH-5a, or EH-5.Flashunits• SB-N5: The SB-N5 has a Guide Number of 8.5/27.9 (m/ft, ISO100, 20 °C/68 °F; Guide Number at ISO 160 is 10.8/35.4). Whenmounted on the Nikon 1 V2, it supports i-TTL and manualflash control.• SB-N7: The SB-N7 has a Guide Number of 18/59 (m/ft, ISO 100,20 °C/68 °F; Guide Number at ISO 160 is 22.8/74.8). When mountedon the Nikon 1 V2, it supports i-TTL and manual flash control.A Guide NumberTo calculate the range of the flash at full power, divide the GuideNumber by the aperture. For example, at ISO 100 the SB-N5 has aGuide Number of 8.5 m or 27.9 ft (35 mm zoom head position);its range at an aperture of f/5.6 is 8.5÷5.6 or about 1.5 meters (orin feet, 27.9÷5.6=approximately 5 ft). For each twofold increase inISO sensitivity, multiply the Guide Number by the square root oftwo (approximately 1.4).