The speedlight requires 4 AA batteries.There are several modes. Manual-full power manual. TTL-TTL with Nikon film cameras. It does NOT do TTL with digital SLRs. MD-"motor drive" mode. It fires at approx. 1/16 power (manual) to keep up with a motor drive. The secondary flash does NOT fire in MD mode (it does in all other modes). A1 and A2 modes-non TTL auto. This mode is where you set the flash and camera to the same ISO and f stop. And the sensor on the front of the flash determines correct exposure. For example, at 100ISO, you select f/8 in A1 mode and f/4 in A2. At 200ISO, you select f/11 in A1 and f/5.6 in A2. I do not like the f stop choices. At 100ISO, the largest aperture you can shoot at is f/4. Many flashes allow f/2.8 or f/2, which I prefer. There's a round dial "computer" on the back(I think that's what they called it back then). It does not change settings, just lets you know the flash range when you rotate it to the proper position. It has 4 zoom settings-28mm, 35, 50 , and 85. If using it on a DX sized sensor camera, divide these numbers by 1.5. That means at 28, it should provide complete coverage with a 18-xxx zoom lens. If you need to use with a wider lens, there's a Nikon SW-7 wide angle adapter available. Then you can use it with a 24mm lens on FX/35mm bodies and 16mm lens on DX. The flash tilts up 90 degrees. It rotates 90 degrees to the right and 180 to the left. That's great for bouncing light off of white walls and ceilings. There's a secondary flash that always shoots forward, regardless of main flash head position. It's good to provide some fill light. But if your subject is close, about 8 feet or closer, the secondary flash will overpower the bounced light. There will be very little bounced light in the photo and it will look like direct flash. This can be remedied by mounting a 1 stop neutral density gel over the secondary flash.