Aug 24th

2009

Exposure and Metering.

boat

After Friday’s post on how I deal with white balance, I got a nice email from Ryan Marco asking me about how I go about metering. He asked a lot of good questions about how I determine where and how I meter the light in a scene. Many of you might have the same questions. And I’m about to disappoint you with my answer. I just point the thing and shoot.

First some background. When I shot film I got very good at taking readings off anything that was middle grey, or close to it, and then, using the Zone system, making adjustments from there. Those were simple times. I never used a handheld spot meter, never got too bent out of shape about things, and bracketed a stop in either direction when in doubt. It didn’t hurt that I was using mostly negative film with a broad dynamic range.

So when I tell you my approach to metering in digital leans to the side of simple, you know the background. As with white balance issues, life is just too short for neuroses on this matter. I lean towards the artist more that the geek most times anyways.

But here’s the bigger issue; it doesn’t matter. I suspect I’m going to get in trouble for this, so the caveat is that this is what works for me. But the thing is, digital capture is different than film. What matters, assuming you’re going to take the digital negative into the digital darkroom, is getting the best digital negative. The best digital negative is not the one that looks perfect on the LCD screen. It’s not the one where you nail the exposure using a spot meter. It’s the one (wait for it, this is paradigm-shifting stuff, here) that has the most digital information, even if it looks like crap on the LCD.

I cover this in Within The Frame (pg 44-46) but let me take another stab at it here.

The more digital information in that digital negative, the more able you are to create a final print with greater quality, less noise, and more awesomeness. So before I go into this, you need to remember: the image on the LCD will most likely look like crap. That’s OK. Use the LCD to preview composition and focus, and then pay attention to the histogram to determine exposure.

How do you know you have the best possible digital negative with the most digital information? The histogram. Forget studying your metering modes and learning the fancy voodoo light mojo. Learn to read your histogram, that cryptic graph of peaks and valleys on the LCD screen. You might have to consult your manual to find out how to access this. For most Canon DSLRs you just press the preview/play button and then the info button once or twice until your histogram appears.

histogramThis is the histogram from Adobe Lightroom, but the one on your LCD will look similar. The histogram above represents a scene captured with no blown highlights – notice the mountains and valleys don’t go off the right-side of the chart – and no plunged shadows – notice the data doesn’t go off the left-side either.

Now, I’m going to assume you know nothing about the histogram. It’s a graph, that’s all it is, and it’s deceptively simple. that graph represents the light values in the scene you’ve just captured at the exposure values you’ve captured it at. On the far left are shadows with no details, totally plunged shadows of darkness. On the far right are highlights with no details, total burned out whiteness. And between those two extremes are all the tonal values from black to white. The height or shapes of the peaks and valleys, for this exercise, don’t matter. Ignore them. You can do something in-camera with where the peaks and valley sit from left to right, but can’t do a thing about their height or shape. That’s the scene. Ignore it.

Why the histogram matters now gets – for a moment – a little more complicated. It’s logical that as long as you get the whole scene into the box of the histogram – neither wildly over nor under-exposed – you can tweak the rest in Lightroom and be done with it. Simple, perfect exposure, right? Wrong. You’ve created a digital negative but not a good one. Why? Because the histogram reflects some quirky math that can only be understood by wizards and occultists, and it doesn’t respond to the logic of mortals like you and I.

Remember I said the best digital negative was the one with the most information? Well the right half of the histogram is capable of storing exponentially more information in it than the left half. WAY more information. And the right quarter of the histogram, WAY more than the other three combined. How much more? Again, I’m simplifying, but if the right quarter of the histogram can hold 2000 levels of information, the quarters to the left of it can hold 1000, 500, and 250 respectively. There isn’t much information at all in the darks. That right quarter of the histogram can hold twice what the rest of the entire histogram can hold.  It’s a WAY bigger bucket, can hold more information. More information means better image quality and more flexibility in the digital darkroom before noise becomes an issue.

So what do you do with this knowledge?

Here’s how I approach exposure. First, I shoot on AV mode or Manual almost 100% of the time. I leave my metering on whatever your camera’s equivalent of centre-weighted average is. Then I take the shot. Click.

Before you look at the images/histograms: I did this in Lightroom as a simulation only and it’s meant to be an illustration, so don’t get hung up on the EXIF displayed on the histogram, it won’t change and will only confuse you. Look at the image relative to the how the information is distributed in the histogram.

exposure1

I look at the histogram. Way too dark. Barely has any information in the right half, never mind the rightmost quarter. Then I use the EV+/- function on my camera, push the exposure a stop, try again. Click.

exposure2
Getting better. But while the image LOOKS OK-ish on the LCD screen, the histogram is telling me otherwise. It is still, in terms of a good digital negative, underexposed. So I go back to my EV +/- and bump it another stop. Click.

exposure3
Much better. Might be a little light for my taste, and where’d my clouds go? Doesn’t matter, I know they are there because none of the scene has disappeared off the edges of the graph. You’ll bring them back in Lightroom or Aperture. Look at the histogram – it’s where it should be, as far over to the right without going off the end. What matters is that now you have LOTS of digital information.

Now I have a digital negative with as much information as possible I can bring the image into the darkroom and adjust it as necessary. In this case I like the luminosity of the boat and the ocean but it was the clouds in the initial scene I loved and have lost. Should have had an ND grad filter in my pocket but didn’t. So in this case I’ll use the gradient filter in LR to darken the sky and punch the clouds – Clarity rocks for this. I’ll make a few more tweaks – including a grad filter along the bottom with Clarity set to -100 to soften foreground waves, and the brush tool with bumped exposure, brightness and clarity to pop the sails.

Here’s the final image (crappy composition and all)

boat-final

So the name of the game is getting to know your histogram so you can create the best possible digital negative. And the best possible digital negative is what, class? The one with with the most information. There will be times when you have a scene with a larger range of tones than the camera can capture. In this case you have options; several of them. Decrease that range with the use of ND grads to reign in the highlights, or a flash to pop the shadows. Or you might take 3-5 bracketed exposures and bring them together in Photomatix or Photoshop. Or you can just make a choice to create an image with either plunged shadows and/or burned out highlights. (page 45 in Within The Frame has a great example of an image with a histogram that goes wildly off both ends.)

My way isn’t the only way, I’m sure of it. But it’s what works for me. I used to meter then shoot, now I shoot then meter. “Same, same, but different,” as they say in Asia. Does this help? Questions?

If this was helpful and you want more, or if my lunatic ravings didn’t convince you, I urge you to spend $9.95 and download Darwin Wiggett’s article Expose Right. You can find that article HERE on Darwin’s site. Highly recommended.

Comments (52)
  1. August 24, 2009 at 2:51 am

    I’m finally understanding that “expose to the right” thing. Thanks for the clear explanation.

  2. August 24, 2009 at 3:54 am

    [...] After Friday’s post on how I deal with white balance, I got a nice email from Ryan Marco asking me about how I go about metering. He asked a lot of good questions about how I determine where and how I meter the light in a scene. Many of you might have the same questions The rest is here:  Exposure and Metering. [...]

  3. August 24, 2009 at 4:07 am

    Great article. Do you know if there is an equivalent feature to “Clarity” in Aperture?

  4. Alex

    August 24, 2009 at 4:25 am

    Perfect! Great explanation of your technique. Within the Frame, I am mid-way thru it. It is BRILLIANT! Go buy it.

    Question: You mentioned the use of centre-weighted metering mode, can matrix mode (Nikon) be used the same way and in what type scenes would you use it?

  5. August 24, 2009 at 4:30 am

    Joshua, Aperture has Definition. They’re probably slightly different, but I believe that they try to do the same thing.

  6. August 24, 2009 at 5:01 am

    Thanks for the article David, was reading about the very same thing last night on Luminous Landscape ( http://www.luminous-landscape.com/tutorials/expose-right.shtml if anyone is interested) and I was kind of wondering if anyone else thinks the same about it. Now I know someone else does :)

    such a shame, I would of knew this by now since I ordered your book on 7th of August and I haven’t got it until now :( ( bad Amazon UK, bad !).

    Anyway, great reading as usual, thank you.

  7. Andy Wilson

    August 24, 2009 at 5:46 am

    Very clear illustration and a light coming on in my brain somewhere realising that I can use the gradient tool for more than exposure…doh!

  8. August 24, 2009 at 5:53 am

    Wonderfully put old man – I’m only going to link to you for the second time in as many blog entries. Thanks for making it easy for so many.

  9. August 24, 2009 at 6:18 am

    A long time ago I read an interesting article about this subject at Luminous Landscape. Just follow Cezars link. It’s definitely worth a reading!

  10. August 24, 2009 at 6:22 am

    Nice, clear and concise. Just the way we like it.

  11. peter berg

    August 24, 2009 at 6:37 am

    nice – real nice. essential information. thanks.

  12. Gail Carroll

    August 24, 2009 at 7:15 am

    Love how you shed light on this info. I use my histogram, just didn’t “get” why I wanted it to the right. Off to play…

  13. August 24, 2009 at 7:19 am

    [...] Within The Frame, a font of wisdom on vision. And just to prove that David is no hack, he threw out a wonderfully simple technical article today on exposure that was – in about 20 paragraphs – one of the most complete and straightforward takes [...]

  14. August 24, 2009 at 7:35 am

    very clear and extremely helpful. thanks!

  15. Joe

    August 24, 2009 at 10:45 am

    Nice outlook. Serendipity is a good thing. But to test your faith in your easy yolk, try shooting a job as high quality jpegs only-no raw. I suspect you will start paying bettter attention to white balance in the camera. Ansel would have shot raw!

  16. Joe

    August 24, 2009 at 10:48 am

    Oops – above comment psoted in the wrong spot – should have been in the White Balance post comment sections. My bad.

  17. Joe

    August 24, 2009 at 10:49 am

    Oops – above comment psoted in the wrong spot – should have been in the White Balance post comment sections. My bad.
    Sorry… forgot to say great post – can’t wait to read your next one!

  18. August 24, 2009 at 10:50 am

    [...] duChemin has got a very good article today about working out exposure and metering in digital photography. Very valuable informations [...]

  19. Melissa H.

    August 24, 2009 at 11:09 am

    Light bulb moment! Thanks so much!

  20. August 24, 2009 at 11:17 am

    I particularly like “shoot, then meter.” I used to meter first with film too. I always attempt to get as much info as possible in my HiSTO but didn’t realize how much more the right quarter “bucket” could hold. Thx, D, for the added insight!

  21. August 24, 2009 at 1:58 pm

    Excellent. It is so hard to follow the histogram rather than the image in the LCD. This tutorial also makes clear that we can save ourselves a bunch of time in post-processing by remembering to have a split ND filter along (of course, one has to take it out and use it; you heard that, didn’t you, Jack?).

  22. August 24, 2009 at 2:12 pm

    PS – I stole from your blog and posted this for tomorrow on my international Aminus3 blog. ” USE YOUR HISTOGRAM – On his blog yesterday, David duChemin talked about “Exposure and Metering”; http://www.pixelatedimage.com/blog/2009/08/exposure-and-metering/#comment-7332. His main point was that we need to pay way more attention to our histogram than what we see on the LCD screen. Here is a crucial quote, “the right half of the histogram is capable of storing exponentially more information in it than the left half. WAY more information. And the right quarter of the histogram, WAY more than the other three combined. How much more? Again, I’m simplifying, but if the right quarter of the histogram can hold 2000 levels of information, the quarters to the left of it can hold 1000, 500, and 250 respectively. There isn’t much information at all in the darks. That right quarter of the histogram can hold twice what the rest of the entire histogram can hold. It’s a WAY bigger bucket, can hold more information. More information means better image quality and more flexibility in the digital darkroom before noise becomes an issue.” This is why all of the pros say, Expose to the right. If we expose to the right (without clipping), we will be capable of producing far, far better exposed photographs.”

  23. August 24, 2009 at 3:07 pm

    Whoops! I screwed up on the URL. Corrected it on my blog.

  24. Megan

    August 24, 2009 at 4:00 pm

    As a newbie I find your approach so simplistic yet it yields excellent photographs. Reading on the web and other books everyone tries to tell you that you have to learn all the ins and outs of photography to be good. Thanks for making bringing it down to a simple science so that us newbies have more of a chance to work on our artistry rather then our geek – because that is why I love photography.

    Quick question though – you mentioned fill flash – what is your method for determining how much to use? I’ve only succeeded once with this and I think it was just a lucky shot because I cant seem to get it right again.

  25. August 24, 2009 at 6:54 pm

    I’ve wondered for a long time if there is any good reason why a modern digital cameras couldn’t have an exposure mode that “exposes to the right” rather averages to 18% grey. It wouldn’t be very hard to implement. Am I missing something?

  26. August 24, 2009 at 7:26 pm

    [...] David duChemin, who is an amazing photographer and humanitarian, has a post about how to meter in digital photography using the histogram. I learned more about how to ge thte correct exposure in digital in five minutes of reading than just baout anything else I’ve ever done. Check it out at the pixelatedimage blog  here. [...]

  27. August 24, 2009 at 7:53 pm

    David,

    A wonderful simple explanation that I will begin using right away. The explanation of the amount of information in the different quarters of the histogram explains a lot.

    Thanks for the brilliant explanation.

  28. August 24, 2009 at 10:52 pm

    Great shot explanation to something that is oft-over explained… Just wish I could get the histogram on the thumbnail on my LCD at the same time….

  29. August 24, 2009 at 10:58 pm

    Thanks for the detailed explaination…really helped in understanding especially the values stored in different quarters…
    BTW…that same same but different is unique to thailand…u won’t get to listen anywhere else i guess…IMO u just stole the thunder from Thais ;)

  30. Simon

    August 25, 2009 at 2:41 am

    This was very clear and concise, in future if anyone asks me about exposure, I’ll send them here! Thanks.

  31. justin

    August 25, 2009 at 9:27 am

    Wow! Thank you so much for this. I’ve been going at it all wrong for so long; and now I finally understand the histogram. I always knew that eventually I’d regret never bothering to learn about something that I thought was so difficult but is actually a piece of cake. For years now I’ve been purposely underexposing my images thinking ‘the darker, the better’. Now I know to ignore my LCD screen and just pay attention to the histogram.

    Thanks again man. Can you please post more stuff like this in the future?

  32. August 26, 2009 at 12:36 am

    Great post! I just thought of one thing that I think is worth mentioning. Make sure you don’t blow out any of the separate channels. I think it helps if you have a camera that can show a histogram for each channel. Exposing on the edge to the right of the histogram increase the risk of blowing out just a single channel that you might miss if you only look at the summary histogram for all the channels.

  33. Marco Ryan

    August 26, 2009 at 5:55 am

    Wow – great response, David. Glad I asked the question now!
    Marco

  34. Joe

    August 26, 2009 at 9:59 am

    Are you sure that the histogram is on a log scale? I know that this isn’t the case in lightroom. The vertical tic marks on the x-axis represent % of 255, and each section on this histogram has the same number of brightness levels. Does the histogram on the back of the camera show stops on the x axis, or does it match lightroom?

  35. scott

    August 26, 2009 at 8:47 pm

    can you explain what has been lost (if anything) in your final graph… the far right hump appears to be clipped at the top? you don’t seem to worry about it.

    i now know where my histogram feature is located and am prepared to use it! many thanks.

  36. September 1, 2009 at 9:24 am

    Great tutorial on histograms. Lots of good stuff here I never even thought of, I always thought I should be working towards the left. WRONG!

  37. September 2, 2009 at 6:54 am

    That is the best tutorial on the digital image I have ever read, regardless the topic. Dude, you’re a teacher. I was researching light meters last night as I just got strobes AB1600 and AB800. A thought flashed through my head, I don’t need a LM as I can just read the image with my art eyes and the histogram with my thinking eyes. I knew what to do but not really how to do it, now I have a baseline and can build on it. Thanks!!

  38. September 24, 2009 at 8:01 am

    [...] Exposure and Metering Learn how to use the histogram on your camera to capture the maximum amount of information. (tags: learn exposure histogram exposing tutorial helpful education educational basics) [...]

  39. October 13, 2009 at 2:02 am

    [...] Last Friday I posted a short slideshow of images shot in Lamayuru, Ladakh. Thanks to all for the kind words left in comments and sent in emails. There were a number of requests for a how-to, so I’ll do my best to be helpful. Truth is there isn’t much to tell in terms of technique. I pointed the camera and let it do it’s thing while I worried about not getting trod on by a horse, donkey or yak. In situations like this the meter on my 5D does remarkably well. But remember, HOW I meter is not as relevant as what the histogram looks like. I shoot first, meter later. Sort of. HERE’s an article on that. [...]

  40. October 28, 2009 at 2:01 am

    [...] try to pull much detail out of underexposed shadows, which is why I expose the way I do (HERE’s an article on that). I don’t use Noise Ninja, never have. I’d probably benefit [...]

  41. Stephen McCullough

    October 31, 2009 at 6:13 am

    Interesting take David. Whether or not someone uses this methodology the simplicity is attractive. On the Luminous Landscape there was a recent post about adjusting the contrast on a camera’s LCD screen: the piece has some relevance to your approach:
    http://www.luminous-landscape.com/tutorials/right-hista.shtml

  42. January 5, 2010 at 2:34 pm

    [...] As you can see, it’s a completely different image and feel in the original to how it’s ended up, but in reality very little has changed. The histogram is the big tell-tale on what’s been done to the processed image, as is the boost in vibrance and saturation and for more on the histogram and how that affects your photography David duChemin gives a much better explanation than i’d manage, here. [...]

  43. February 21, 2010 at 2:47 pm

    [...] an article from David duChemin regarding Exposure and Metering (which includes histogram): Exposure and Metering __________________ [...]

  44. February 23, 2010 at 4:25 pm

    [...] You can see  his work at his site (http://www.pixelatedimage.com/) and I recommend to have a look at his series of ebooks.  Very well written with lots of valuable information on how to cultivate your vision, accompanied with very beautiful images. You can read  the original article from David at his blog (here’s is the link) [...]

  45. April 11, 2010 at 9:44 am

    [...] PixelatedImage – Exposure and Metering. [...]

  46. July 27, 2010 at 4:56 pm

    [...] are a couple I found right off the bat.. Both are reputable sources. Expose Right Exposure and Metering. __________________ Luke. My flickr GIMP fanboy AIP ga hokoreru [...]

  47. August 8, 2010 at 5:40 am

    [...] time ago I stumbled across this article Exposure and Metering. and it greatly benefited me..I'm sure it would benefit u as well… __________________ [...]

  48. August 17, 2010 at 11:03 am

    Actually David, the amount of information recorded at each of the available 256 levels of tone (the data the histogram is showing you) is identical. Where you run into differences is when you add hue. I can’t explain it all in a comment. You need to read http://jims-ramblings.blogspot.com/2010/02/right-idea-wrong-reason.html

  49. June 3, 2012 at 2:34 am

    wow the final image so beautiful, like a masterpiece painting….