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Relevant tones

ilovelightilovelight Member
edited October 2013 in home
Hi Everyone,

I'm reading the "on-camera flash" book and came across these sentences:

"The right-hand edge of the histogram will show us where the brightest relevant tone should be. The word relevant needs to be stressed."

"The Nikon histogram looks slightly different. In my experience, I get an optimally exposed image if I place the edge of the histogram (for the brightest relevant tone) just shy of the corner of the histogram display. (There’s that term “relevant” again. It’s an important distinction.)"

Which "relevant tones" are we referring to?

Thanks for your help!


  • Neil vNNeil vN Administrator
    a white t-shirt ... that's relevant to our subject.

    a white picket fence in the background ... not relevant for how we figure out our exposure for our subject. White clouds aren't relevant either, since it's not part of our (portrait) subject.
  • So when shooting we meter exposure on the brighter relevant areas instead of the subjects face?
  • Neil vNNeil vN Administrator
    That depends entirely on how you meter.
    - handheld lightmeter?
    - camera's meter on spot-metering?
    - histogram?
  • As Neil said the brightest or whitest relevant tone , such as the brides dress details not being blown out ( important) or the clouds behind the bride being nicely exposed (not so important) but loosing the dress. I zoom in, spot meter for the dress, and use fill flash if necessary for the faces.
  • When we expose correctly the white areas (dress), wont the darker areas become too bright?
  • TrevTrev Moderator
    edited October 2013
    No, if you expose properly for a relevant tone [White] all the other tones in the image will fall into place in the proportionate details. If you don't expose correctly for the whites, say you are under, then the blacks would then be blocked up, no details, if you over-expose the whites, then yes, the blacks would become lighter but *only* if over-exposed as the whole image is then over including blacks.

    Then in post you maybe would add midtone or black to get more contrast, but as long as you have exposed correctly for the white part that is important it is fine.

    Now, of course if you wanting to use flash, you set the ambient light a tad under correct exposure, then apply flash, but once again as long as the whites in the important areas show up correctly with the use of flash, then the rest of the image [only where the flash falls, it won't affect any dark backgrounds back from subjects] will follow suit.

    If there are no whites, and all midtones like grass, colors, etc. you could just take a general meter reading and zero it out on the camera, but that's only if not wanting to use flash as your dominant light source, you can still zero it all out and use flash, but the flash should then be set to say 1.5 to 2+ stops under so it's just a blip of fill flash to help with eye sockets, etc.
  • Neil vNNeil vN Administrator
    ilovelight said: When we expose correctly the white areas (dress), wont the darker areas become too bright?
    No, the darker areas will be placed correctly, according to their tonal values.
  • Thank you so much Neil and Trev!
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