For some reason, a negative meter appears each time I attach my 910 flash to my D90 and attempt to shoot in A or P modes. It disappears with I remove the flash. Any ideas what's wrong? I reset to default but with no change.
I didn't note the speed. I tried to change to another of the settings recommended by the camera with the same result.
I had forgotten that I had had a problem last year with the built-in flash firing in bright sunlight, in auto and P modes without me setting it to do so. So there could be a problem with the camera - or I somehow got one of the settings messed up. I'm moderately new to all this. Perhaps I need to send it to our local repair center to see what they think and on to Nikon if they can't fix it.
There probably is not a problem. Remember that there is a setting to select the minimum shutter speed allowed when using flash. The default is usually 1/60th of a second. The meter reports the reading for the ambient light.
When you put the flash in the shoe, the camera might be changing to 1/60th which is too fast for the existing light and aperture you have selected. When you remove the flash, the speed might drop to 1/30th (as an example) which is adequate for the existing light.
Scott Chapin Powder Springs, GA, USA Nikonians Team Member
You might want to check your Exposure Compensations and set them to '0'. Your SB-910 mode should be set to TTL FP for normal flash or TTL BL FP for fill flash. Check your Flash Sync Speed, i don't have a D90 but believe it should be set to 1/250/s (Auto FP) and Flash Shutter Speed to 1/60 and set Flash cntrl for built in flash to TTL. That should help. I don't know you level of proficiency. It sounds like you are in auto modes. You might want to try A (apperature priority) or S (Shutter priority) which are semi-automatic modes letting you set ISO and letting the camera select the proper shutter speed or aperature. You may need to adjust the Apperature or the shutter speed or ISO until you get the green light in your viewfinder.
Fri 03-May-13 08:56 AM | edited Fri 03-May-13 08:58 AM by elec164
Don't use Auto-ISO with flash or you might find the camera setting a higher ISO then you might desire.
What you are experiencing is most likely normal behavior. Remember that with flash you basically have two exposure readings for ambient light and flash. The camera meter shows the ambient exposure, the flash iTTL is handled by the camera and is transparent until you chimp.
In A and P modes the meter will not be displayed unless the camera cannot set a null exposure. So in your inital request the shutter speed set for the ambient light when in A or P mode may be lower than the sync speed setting you've chosen for the flash. As Scott already explained, when you turn on the flash and the shutter speed jumps to sync speed, the meter will appear showing the deviation from a nulled meter.
To see this for yourself, you can get the meter to appear in one of the semi-auto modes by dialing in EC. Dial in a -1 EC And the exposure meter should appear showing the 1-stop under-exposure. Set a +1 EC and the meter will show 1-stop over-exposure.
Thank you. That is helpful. I wasn't aware of the balancing between ambient and flash illumination. I have the book on the Nikon Flash System. Not doing much good unless I actually open it and transfer its knowledge into my old mind. (I saw a cartoon recently. A small boy is holding a book, looking at it quizzically. His teacher says "It's a book. It's how people used to upload new software into their brains.")