Mon 22-Aug-11 02:04 AM | edited Mon 22-Aug-11 02:43 AM by dm1dave
As indicated, I have a D7000 and an SB600 flash that I'm using wirelessly with the built in flash as the trigger. I've checked all my settings and as far as I can tell, I have all my settings correct, yet I am getting shadows from the built in flash. My hunch (and that's all it is), is that it's firing for too long a duration. Any suggestions greatly appreciated.
The pre-flashes for AWS, Advance Wireless System, occur before the shutter is opened, but the flash trigger signal only occurs after the shutter is opened and before it closes. The exact time is dependent on whether you are using normal or rear sync.
To remove the light from the trigger flash, you need to use the SG-3IR or block the visible light from the pop-up flash.
Not it just changes the triggering pulse form just after the the shutter is fully open to just before the shutter starts to close. You need to make the light IR, Infra Red, and not visible.
The AWS system uses IR remote just like a TV remote, but when an IR source like the SU-800, is not available, then the visible light of the pop-up, or the SB-900/800/700 is used with the control signal in the IR portion of the visible light.
OK. The reason I mentioned the CMD mode setting is that by default the onboard flash is set to TTL - this means it fires to illuminate the scene.
So, when you set your SB 600 up for remote activation and select CMD mode for your onboard flash, what you'll get is TTL flash for both the onboard and remote flashes.
If you're using a hood or longish lens, the onboard flash will cause a shadow on the subject.
If you go to the Flash/Bracketing settings (Menu E3), select CMD and press the right direction again you'll get to a screen where you can choose the mode of the onboard flash. It's TTL by default so it fires to illuminate the scene - set this to "--".
I've had this happen a few times to me so maybe that's what you're getting now.
The reason flash powder, flash bulbs, strobes, and Speedlights need to be synchronized to the shutter is that the light emitted by these devices needs to provided while the shutter is open. These light sources can and do emit light in a burst shorter than the time the shutter is open. So if you use an optically triggered remote flash the trigger light is emitted when the exposure media is fully exposed and the leading and trailing focal plain shutter leaves are not covering any portion of the recording media. If either leaf were covering any portion of the recording media, then there would be a dark edge either at the top or bottom of the recorded image. This is why the control trigger flash needs occur while the shutter is open.
Both images show the shutter status, preflash, trigger flash, and illumination flash of the Master unit or only the trigger flash of the Commander unit.
You can also use a long shutter speed, and rear shutter sync to observe for your self the trigger flash does occur after the shutter is opened and before the shutter closes by carefully listening to the camera sounds and observing when the flash triggers.
Nikon has posted sample images in the article I linked to about the SG-3IR along with the following text:
"When pictures are taken at close distances with the Nikon Close-Up Speedlight Kit, the built-in flash on the D70, D70s and D200 when set to Commander Mode, may slightly affect desired results. The SG-3IR may be used to prevent shadows and allow the SB-R200 to highlight the subject as illustrated in the examples below."
Even though this article specifically list the issue with SB-R200 the issue applies to all Nikon AWS Speedlights irregardless of the model when objects that are close to the camera.
gkaiseril, you did not misread my previous post, that is the issue. I would attach a sample image if I knew how. It may be that my subject is too close to the bacground, but I have tried setting the remote flash at different points around the subject, with no luck.
Tue 23-Aug-11 12:25 AM | edited Tue 23-Aug-11 12:32 AM by gkaiseril
You need to get an SG-3IR, follow the link to see what it looks like. You might be able to hang a business card in front of the pop-up flash and have the light reflect to the flash's sensor. Others have use red filters over the pop-up flash to accomplish the same affect that the SU-800 does. If you use anything in front of the lens, leave some air space between the filter and the flash head so the filter does not melt onto the flash lens. The pop-up flash is not high enough so the FOV, Field of View, for the pop-up flash to clear some lenses or lens hoods. Another option is to get an SB-900/800/700 which can move the flash tube above the lens/hood or you use an SC-17/28/29 cable and flash bracket to the the flash head even higher.
The SU-800 uses a red filter over the flash tube of an SB-800 and only allows the IR light out and thus the trigger flash is not picked up by the camera.
A simple solution is to turn off the on-camera flash so that it simply signals the remote flash with pre-flashes but does not fire during the actual exposure.
Another solution is to reduce the power of the on camera flash.
As suggested, you can move the subject further from the background where the shadow occurs. And the shadow from the lens hood or lens barrel is also a potential issue for the on-camera flash.
A related option is to use a reflector or white card to bounce the flash and illuminate the backgorund. That can be done by pointing the flash toward the ceiling or bouncing it off some other surface - even your hand. Likewise you can diffuse the flash with a diffuser or similar tool.
1: How can I turn off my built in flash so that it only emits a pre flash? (remember, I've only had the camera a week)
2: Any suggestions for outdoor lighting using the flash remotely so that the light isn't too harsh. I can't seem to dial it down if it's not mounted to the camera and I don't have any reflectors or such things. I have to do an engagement shoot this weekend and I'm having more trouble figuiring this combination out than I thought I would.
The shoot will be outdoors, at a cascading waterfall, there is a small crevace in the rock wall near by that I can use as well, but shadows would be a real concern there with the issues I'm experiencing so far.
Follow the link for I posted for the SG-3IR for a Nikon posted sample showing the problem and solution and look at the pinned post in the Speedlight and lighting forum about the pre-flash sequences and you will see the sequences of flashes and the shutter status, notice that after all of the pre-flashes, there is at least one more flash while the shutter is open.
Setting the Speedlight to "--" uses the lowest possible power level for the trigger flash but it does not eliminate trigger flash. Even with the trigger flash at the very lowest power level its emitted light will be captured by the camera but it is of such a low power level and even distribution that the affect fades pretty quickly or is not usually noticeable as long as there is no obstruction within the projected light.
If an object, lens hood or lens barrel, is within the cone of light projected by the pop-up flash, even at the very lowest possible power level a faint shadow is created form this light source and that shadow can appear in the captured images.
The other solution is to purchase radio frequency, RF, flash triggers. There are inexpensive units but one loses the iTTL features. PW and radiopoppers have iTTL compatible RF triggers but they are not inexpensive.
I do not think it does, as shown by the pre-flash sequences in the lighting forum, the power of the trigger flash is reduced but not eliminated and as shown by Nikon there can be a shadow picked up even when the camera's pop-up flash is set to "--" in the commander mode.
Yes you can trun off the pop-up flash, but you will also disable the remote AWS units.
Just because the user manuals state that it is only pre-flashes, it does not say anything about the trigger flash. This is one of many issues with the accuracy of Nikon's user manuals.
The built-in flash has to fire while the shutter is open, because it's that pulse of light which triggers the remote Speedlight. Setting the built-in to "--" will minimise the light emitted, but there will still be some. If the subject distance is small, a shadow can be created from some large lenses/hoods.
As mentioned earlier, the little SG-3IR device would block the visible light but let infra-red through - which is all the Speedlight needs
Absolutely right bout lens ans use of hood. I discovered issue using syncro sun technique and whe sbooting in St. Louis where the hood was necessart to prevent flare from street lamps in the club zone. ARRGH. You can't see it on the little screen and shooting NEF. Thank god for pbotoshop though. LOL