>>kellenfreeman wrote: Panamon_Creel, I almost feel like if you take the time to position the external flash, then no matter how low you set your on camera flash, it's going to provide light that you really may not want... right?<<
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>>Willis wrote: It will only contribute to the exposure (which happens after the pre flash) if you have it set to fire a second time (adjust the master flash to -- in your CLS menu).<<
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Setting the internal flash to Commander only mode (--) means that the internal flash is only used for sending commands via low power light flashes to the external flash unit(s)and that it is not directly contributing to the exposure. However there is a little twist to the CLS system in that the internal flash will fire a low power flash pulse as a sync signal to the remote flash gun(s)when the shutter is fully open thus could result in unwanted illumination in some situations. Note that this sync flash while the shutter is open occurs in normal flash exposure and not in High Speed FP flash mode.

The transmitter (SU800) and the pop up flash do exactly the same thing - Emit a infrared pulse that triggers all the flashes. For the pop-up to do this, it must fire its normal flash as well (the flash releases both frequincies... you just can't see the IR. Camera filters can see all the wavelengths that our eyes can't. To keep them from messing things up, manufacturers put IR filters over the sensors to remove the light before it hits the sensor.

Your pop-up triggers the remotes with a pre-flash. It will only contribute to the exposure (which happens after the pre flash) if you have it set to fire a second time (adjust the master flash to -- in your CLS menu). Sometimes you can catch a reflection of the preflash in your shot, but otherwise the effect is negligible.

The limitation with both the Nikon transmitter (which is really just an IR flash) and the pop-up, is that they are using high frequencies that travel only a short distance and can't penetrate solid objects. If you move down the spectrum to radio waves, then you get lower energy, further traveling waves that can move through things like walls, light mods, and over sized lighting assistants. This is why you get radio in your closet, but you don't get sun-light). Radio is a better solution for long distance transmission, but its also harder to choreograph in such a way that you can calculate things like TTL exposure. That's why most radio poppers restrict you to manual control only.

Panamon_Creel, I almost feel like if you take the time to position the external flash, then no matter how low you set your on camera flash, it's going to provide light that you really may not want... right?

Also, a lot of you guys seem to be leaning toward the IR cover as a good alternative instead of the transmitters... true?

Update: I'm getting my stories all confused. I meant to say that the SB600 doesn't have a SU-4 mode. No big deal for what you are trying to do. You can use the SB-600 with any trigger that runs off a hot shoe. Otherwise, You'll need to rig up some unseemly adapters.

There are, however, some issues with the SB-600 and the cactus V4's that you can read about here http://www.flickr.com/photos/peter_bromley/3541781929/

Basically, you have to modify the trigger slightly in order to get the SB600 to fit properly.

I don't think you can use a SB600 with the Cactus transmitters. The SB600 doesn't have a manual mode. It also doesn't have any PC jack, so triggering it can be kind of problematic. There are cheaper alternatives to the SB600 that work very well with remote triggers.

An IR filter over the built in flash is only required if the low level commander mode flashes would provide unwanted light in your scene (e.g. towards mirrored surface). The NIKON SG-31R IR panel mounts on the hot shoe of the camera and the panel flips over the extended built in flash to filter out the visible light. A low cost self made IR filter can be made by taping a piece of unexposed developed 35mm negative film over the built in flash.

Yeah, you could put a custom IR filter over your flash (so only IR light get's through for the commander) and get 2 or 3 more SB-600's, some good stands and soft boxes and you will be set for small events.

The Cactus would allow you to shoot when the commander can't reach the sensor on the off camera flash unit's (helpful out doors, especially).

It only get's more expensive from there.

The next best thing would be to get a power pack and some flash heads, synced with a pocket wizard.

I was recommended to look into third party stuff (as the Nikon transmitters are expensive) and was recommended the Cactus V4. What are your thoughts? I've also been recommended to just use a filter over my on-camera flash and use it in commander mode.

I have a D90 and an SB600... Just looking for general advice, not necessarily for an imminent purchase.