The Neewer TT660 camera flash fits various standard hot shoe DSLR cameras.It has a guide number of 190 in feet with ISO 100 at 105mm, allowing you to place the flash away from the subject. This Neewer camera flash features a 24 to 105mm auto zoom range. With the shortest flash duration of 1/20,000 second, this shoe mount flash helps you to capture high-speed objects in complete darkness.
Using the TT660 Flash: 1. Power Management: Power Switch set to ON, and the flash will start charging (the charging indicator is dim). After several seconds, the charging indicator turns red and the flash unit is ready for firing. For a test flash, press the Test Button. After use, power off the camera flash by setting Power Switch to OFF. If the charging indicator blinks in every 1s, the battery power is low. In such case, the camera flash will turn off immediately. Replace the batteries immediately. 2. Power Control: The camera flash has 8 steps of power output control which are indicated by 8 LED indicators. Press "+" to increase the power from 1/128, 1/64, 1/32, 1/16, 1/8, 1/4, 1/2 to 1/1. In contrast, you can press "-"to reduce the power output level.