How to trigger speedlights

Methods to trigger the speedlight off camera

Automatic TTL trigger methods

Nikon Commander/Remote wireless remote system: (Canon has something similar, but I am ignorant of it)

The Nikon Commander could be the internal popup flash of camera models D80 and above. Or it could be an added $250 Nikon SU-800 Commander, or it could be a SB-800 (discontinued now), or it could be a SB-900 (about $440 now). A D40/D50/D60 will need the SU-800 (an unused flash on the hot shoe seems an unnecessary expense when all you need is the commander). The commander must be on the camera, or attached with the hot shoe extension cord. The commander flash can also contribute to your lighting, or not. Your choice, the commander menu has a "- -" choice to disable it. Even when disabled, the commander WILL FLASH commands before the shutter opens. With the commander and a couple of remote flashes, this is a very impressive system, allowing automatic wireless remote point&shoot TTL multiple flash. There are also a few downsides not encountered with manual flash. Much preflashing occurs which causes subject blinking, but camera FV Lock is a work around. See a similar discussion of these differences of Commander vs Manual.

We cannot mix and match Manual flash gear with the Nikon Commander system. Digital camera flash is simply very different than the old days. Optical slaves and hand held flash meters are simply incompatible with all the preflashing done by the commander system. The preflashing will trigger your slaves too early, before the shutter opens, and thus they cannot contribute to your picture lighting. You can use the Commander system, or you can use the Manual system. Just pick one system and go with it, then no problems.

Hot shoe extension cable:

This is Nikon SC-17, SC-28, SC-29 cables. Canon has equivalents for their system.

On this hot shoe extension cable, the flash can use any mode it can do on the hot shoe, but the cable only controls one digital TTL flash. These cables work very well with a hand held flash, just about the right length. They are coiled cords, and may technically stretch to perhaps five feet, however they are actually limited to about 2 feet, because if stretched longer, the coil tension is tight, and probably will turn over your light stand or camera tripod. The loose stand sitting on a table is NOT going to work this way, you will have to anchor it down.

The older Nikon SC-17 cable still works fine, and is plentiful and inexpensive on Ebay. This older SC-17 is the same cable as the newer SC-28, except it does not have the pin hole for the hot shoe lock of the new flashes (which the new SC-28 does have). The old SC-17 still works fine however, just lower the pin and the flash will not fall out, or you can easily drill that hole. I went a few years without the hole in my old cables, and then finally got around to drilling it. Really does not matter.

The SC-29 has an additional AF Focus Assist light at the camera end. The speedlight already has a focus assist light to help focus in dim light, however when off camera, it may not be aimed at the focus point the camera needs. The SC-29 adds one in the hot shoe that will always be aimed directly forward, where the camera needs it. This is only needed in dark places when focus is not otherwise possible.

You can chain up to three of these cables to be a little longer. Each is an extension cord. Or, you can heat the old (inexpensive, expendable) SC-17 in hot water, and straighten out the coils into be an almost straight cable perhaps 8 feet long. A bit kinky and ugly, but it should work well.

Manual flash trigger methods

(no automatic TTL possible these ways, and flash units without a PC sync connector are very limited)

PC sync cable:

You can add the Nikon AS-15 hot shoe adapter to add a PC sync connector to a camera which does not have one. The AS-15 is a particularly good one. Then you can use a PC male to PC male sync cable from the AS-15 to a Nikon SB-800 or SB-900 (Not the SB-600 - it has no PC sync connector). The PC Male to PC Male cables are getting hard to find in standard places, but maybe $20 for a 15 foot cable, and $19 for the AS-15. Studio lights have a different connector at their end, but whatever cable fits your light, you would use that same PC sync cable to a handheld flash meter too (to meter that light). A PC Male to PC Female cable is an extension cord for any of them (it fits the camera end). This method is only Manual operation, no TTL.

Optical slave trigger:

An added accessory, usually added at the flashes PC sync connector, or some fit the flash shoe foot, which triggers the flash in sync when the light from another manual flash is detected. Some Manual flash does have to flash to trigger it. Most studio lights include this optical slave trigger, and they routinely operate this way. We trigger the nearest light some other way, like sync cord or radio trigger, and then that light from the first one triggers all the others. The Nikon commander system above uses a complex trigger signal at minimum power level, but this optical slave uses a simple regular high power flash from any other manual flash, so reliability can be very good. Downside is that any other photographer using flash in same room will trigger your lights too. Manual flash only.

Optical slave triggers are incompatible with digital TTL flash mode. The digital preflash will trigger them too early to contribute. However, there are "digital" slave triggers which can ignore the hot shoe digital TTL preflash, BUT these still CANNOT ignore the commander flashing.

SU-4 mode:

The Nikon SB-800 and SB-900 flashes (NOT the SB-600) include the menu to set them into SU-4 mode, where they become a simple optically triggered slave, such that the light from any Manual flash will trigger them. They will work well with studio lights this way, they become just another optically triggered slave flash. The actual Nikon SU-4 is a separate slave trigger module, and the SB-800 and SB-900 have it this optical slave trigger built in. Some flash does have to flash to trigger it. It could be your pop-up flash, set to Manual mode, and set to lowest manual power - to not affect your picture much, if at all. This low power pop-up is not going to do much to your picture, except at very close subject distances. The main flash will be much stronger. The SU-4 mode flashes are quite sensitive, and 1/128 power from 50 feet away will trigger them, IF their sensor is pointing at the source. Maybe more, but 50 feet is all the space I had to try it. This is Manual flash mode, no TTL.

Radio trigger:

A transmitter module goes in the camera hot shoe, and a receiver module attaches to the flash, usually via PC sync connector, or some models use a shoe foot connector. Radio has advantage of greater range, will go through/around most obstacles, and is not affected by bright sunlight. Battery requirement is high, because the receiver always must be listening. Cost of original Pocket Wizards is high, but there are many inexpensive imports now. Manual flash only, however there is one new Radio Popper brand said to work with Nikon's Commander system TTL.

Opinion: The SB-600 seems the wrong choice if you want to use manual operation. It has a manual mode which works fine on the hot shoe, but it provides no PC sync connector to trigger it off camera. However, the SB-600 does all else very well, as a hot shoe walk around bounce, and Commander/Remote operation, and it will work fine on the SC-17/SC-28 cord. But if you want manual flash mode, then some other brand of inexpensive flash will have the PC sync connector, and won't need the fancy Nikon Remote stuff anyway.