PDA

View Full Version : SB-800 remote exposure question


Tony_V
04-05-2008, 08:38 PM
I was playing around using my SB-800 on a tripod. I noticed all of my shots were under exposed. I did some testing with the flash on the shoe and then remote right next to the camera and there is almost exactly a -.7 EV difference in exposure. I double checked my settings and didn't see anything wrong. Is this difference in exposure normal?

Tony
XaiLo
04-05-2008, 10:26 PM
What mode are you shooting in?
herc182
04-06-2008, 05:29 AM
and sorry to say this, but have you dialed in exposure compensation (in your case under exposure) on your camera?

I always underexpose when not using a flash (because the D80 seems to over expose). I then slapped my SB600 on the camera and wondered why it was underexposing. By the same amount as you mention (thats what i underexpose by).

For me it was a simple easy mistake. Maybe the same for you
Tony_V
04-06-2008, 06:58 AM
What mode are you shooting in?

Sorry, it was late and I was tired.. some additional details would be helpful. :o

The flash mode was TTL. I was not going for balance fill, although I tried that too. The exposure was set to 1/60 and f/2.8 iso 200. The only difference when the flash was in the shoe was iTTL (not BL). During my next to the camera test I also went as far as setting the zoom to the same as it was in the shoe knowing at the distance I was shooting it shouldn't be an issue. I verified there was no exposure compensation dialed in as Herc182 suggested. I also tested the SB-800 against the on camera flash and in the shoe they were identical with the same -.7 stop difference off camera.

To get the same exposure as on camera I wound up setting +.7 EV (flash) for the SB-800 while off camera. Using the SB-800 remote and the on camera flash I had to set -.3 EV for the SB-800 and -1 EV for the on camera flash.

It is also worth mentioning the way I was testing was using the same subject repeatedly and comparing the histograms. There was a spike in the mid tones that made it easy to compare.

Herc, thanks for the response. I've done that exact same thing. I had it right THIS time though.

Tony
XaiLo
04-06-2008, 11:28 AM
Tony_V, I tried the same test and there is a difference in exposure it may have something to do with proximity to the lens. In my test the off camera exposure in appeared to be the correct exposure.
Tony_V
04-06-2008, 08:22 PM
Tony_V, I tried the same test and there is a difference in exposure it may have something to do with proximity to the lens. In my test the off camera exposure in appeared to be the correct exposure.

XaiLo, I don't think the proximity is the answer. I tried the flash in several positions besides right next to the camera with very similar results. I say similar because moving the flash around affects shadows which affects the histogram. It's interesting you got different results on and off camera but they were different than mine. Just curious, was your on camera test exposed higher than off camera?

I've had a rough couple of days. I will post some samples as soon as I can.

Tony
XaiLo
04-06-2008, 08:59 PM
It's interesting you got different results on and off camera but they were different than mine. Just curious, was your on camera test exposed higher than off camera?

I've had a rough couple of days. I will post some samples as soon as I can.

Tony

Tony_V, yes! if by higher meaning more flash power. The D40 does not have a in camera commander, so my testing was conducted with two SB-800s.