The SF 40 Flash from Leica is optimised for use with Leicas latest cameras and features TTL support for automatic exposure and metering, as well as support for slow, high-speed, 1st and 2nd curtain sync modes. It features a guide number of 131 at ISO 100 and 105mm, and a zoom range of 24-105mm, which can be expanded to 16mm with the use of the pull-out diffusion panel. An LED video light is also included, with 9 output levels for high resolution video capture. Tilt up to 90° and rotate 360°. It is also possible to use the SF 40 as a wireless TTL slave flash when paired with a compatible master unit. Recycle time ranges from 0.1-4 seconds and it runs on 4 AA batteries with approximately 220 to 1,700 flashes or an LED run time of approximately 3.5 hours on a single set of fully-charged batteries.