what's tricking my light meter into giving a false reading?

S

sandpiper

New member
hello,
i'm new here at nikonites and i'm hoping someone will help me with a problem i've just encountered...
i got a D300 and a SB800, the light meter is a sekonic 308... they all work well together when the flash is on camera but in CLS the meter is 2-3 stops under the actual output and using yongnuo 622 and tx its 3-4 stops under....
must be to do with signals being sent and received but has any one else experienced the problem and is there a work around?
i have to use the meter in cordless flash mode as i don't have (or want) a cord!

thanks,

Rob
 
W

WayneF

Senior Member
Handheld flash meters are generally incompatible with the Commander. The handheld meter is for real actual genuine Manual mode (the mode called M on the flash - no commander). This will need a way to trigger the flash to be metered. The conventional way is to use a cord from meter to flash, to trigger that flash for purpose of metering. Then you move cord to next flash, to set it, etc. Then move the cord from meter to camera for the shoot.

If using TTL flash mode, the flash first does a low level preflash for the camera to meter. This interferes with a handheld meter, which meters it instead. So the handheld meter simply cannot be used with TTL (and of course, it makes no sense to try to use it for TTL. The camera is metering it, and you have no way for the external meter to control anything in TTL mode).

If using the Commander (any mode, including its manual mode), the commander first sends various low level flash signals to (each) remote (request for preflash, sending the manual menu power level, etc), and this flashing drastically interferes with any hand held meter. You meter the command level instead.

The Sekonic is filtered to keep out infrared, so you could put a Nikon SG-3IR filter on the commander to output only infrared, and then it could work for manual flash, if the Sekonic is at least maybe five or six feet from the Commander (filters are not perfect, leakage occurs, precautions are necessary - try blocking the commander path with your body). And any TTL remote flash is still going to do preflash, which interferes.

I don't know what the 622 does, but any remote TTL flash still does preflash immediately before any flash.
 
S

sandpiper

New member
like you say just blocking line of site from commander to meter has done the trick in manual mode (not using the meter in TTL hehehe! although it'd be good to test the accuracy of the camera meter)
Still not got to the bottom of the meter/YN622TX issue...not even sure what kind of signal it sends? all the reading i've done so far just says wireless, i know its got a AF assist lamp but i've put tape over that!
Anyways if i find a solution i'll report back :)

cheers,

Rob
 
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