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TTL exposure compensation creates opposite effect on metering guide.

SpinFxtcSpinFxtc Member
edited May 2013 in general photography
Just a quick question:

Say I am wanting to expose my scene at a meter reading of zero which i adjust my camera to do so in Manual mode. I then drop my TTL flash down a stop using my on-camera exposure compensation. My exposure meter now shows that the scene is over exposing by a stop (even though I know that its not). What’s the easy explainable reason for this so that i can share it with my colleges?

I know this doesn't effect my outcome and I do correctly expose my shots but I'm just curious as to what this is telling me.

I hope i'm making sense.

My gear i use for this:
Nikon D3s with a range of lenses
2x SB910 speedlights with pocketwizards.

Comments

  • That's not how you should be bringing down the flash exposure. You should use flash exposure compensation (FEC) instead of EC. Press the flash lightening bolt on top of the camera and wheel to adjust FEC.

    In terms of answering your question of why the exposure meter thinks you are overexposing: Because you used EC, you are telling the camera you want one stop less exposure. It is telling you that you will overexpose based on your currently selected ISO, aperture, and shutter. Stick with FEC when you just want to adjust the flash! Hope that helps.
  • I wish I had the FEC option on my Nikon but I don't. The D3s doesn't have that option. It's odd that they left it out on that model seeing it as an improvement on the D3 (which also doesn't have it). The lightning bolt is there but not the FEC option thus me having to use EC to change my ttl exposure.

    i still din tunderstand why if I tell my camera to expose - 1 and my ttl -1 that my camera says that my exposure result will be +1 when clearly it won't be. Hmmmmm my head hurts...
  • TrevTrev Moderator
    edited May 2013
    SpinFxtc,

    On the D3s you have 3 choices with the lightning bolt; nothing [normal] redeye and Rear Curtain.

    To change the Flash Exposure Compensation itself you do that on the actual flash.

    1] press the top left button on back of flash, you will then see in # 2 a value expressed in + or - EV (0.00 EV) highlighted.

    3] When it shows up highlighted [black bar over it] rotate the rear wheel left or right to - or + EV values.

    4] Press OK to set it; or leave it as after a few seconds it will unhighlight and if you need to change it again you need to press that button again to highlight to change values further.

    You can -/+ it up to 3.0EV on the Flash; then you have the added advantage with Nikon (*only* in Manual Mode on Camera) to then use the Camera's Exposure Compensation and that will further -/+ EV under or over.

    Although you can -/+ on the Camera's EC up to apparently 5 stops by itself I don't know if you would have a full -/+ of 8.0 EV for flash, never tried it; I have however done up to -5.0EV with -3.0EV on Flash and -2.0EV on camera body.

    As to why you show over-exposure, I don't know unless you are moving the camera around a bit and picking up more lighter areas in background.

    Does it reflect that in a taken shot? You only mention it 'showing via meter' on camera.

    Because you have the camera set manually, your LCD will vary widely when moving the camera around, remember, it's still 'thinking' re exposure metering and if you move camera around based on your set ISO/Shutter/Aperture it most definitely will show over/under exposure depends where the lens is pointed and what the background is as that dictates the camera's exposure values based on what it sees in the *total* image regardless of what you want to expose correctly.

    Dark backgrounds, light skies: Meter reads differently to each although set manually.

    image
  • Hey Trev,

    Thanks for your reply. I have since worked out that the lighting bolt on the d3s doesn't have the ability to change the flash compensation and that when using manual on the d3s you have to use the EC to change the flash power as well as the on flash FEC to push it that little further. Using the on camera EC while in manual changes the flash without effecting the outcome exposure but it does effect the meter reading in an opposite way. If i dont take this into account then im fine :) And my scene doesnt change when this happens so thats why it bothers me.
  • No. Press the lightning bolt and hold it and at the same time use the front wheel to adjust while looking at the top LCD. The D3S is one of the finest cameras Nikon has built - trust me, it can do flash exposure comp.
  • TrevTrev Moderator
    Nikonguy,

    Sorry, it does not on mine. Camera set to manual, flash on and turned on; hold lightning bolt, turn shutter [front] wheel, nada, nothing shows on top of LCD screen, nor on the flash LCD itself.

    Also trying on the rear wheel, you get what I stated above, normal, redeye, rear curtain.

    So, maybe I may have affected something in my custom functions [not on the flash, only thing in there I changed was having turned off the over-heating and the damn beeping] but in the camera body itself.

    Definitely *not* changing flash exposure per se on camera top LCD screen.

    If it does change like you say, does it reflect on the back of the flash, I prefer to see those changes on back of flash.

    Yep, D3s one of the finest cameras built I agree.

    Trev
  • TrevTrev Moderator

    Hi Nikonguy,

    Just had a thought, firmware, I have not updated from initial purchase, so maybe that's the reason or was this function always available according to you?

    Trev
  • Neil vNNeil vN Administrator
    The D3s doesn't have FEC.

    I am open to being hugely surprised though.
  • TrevTrev Moderator
    Nope, firmware update did not change a thing on either of my D3s bodies.

  • Arrrgh! You're right. Sorry, I was describing how it should work rather than does work. As Emily Litella would say, "Never mind." :-)
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