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Lesson 30 from: Mastering Your Digital Camera

Chris Weston

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Lesson Info

30. Histogram

If each pixel was arranged on a chart based on the brightness and darkness of each pixel, you'd get the histogram. Here, Chris explains how to use the histogram to guide your exposure.
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Lesson Info


digital cameras have some tools to help you check the accuracy of your exposure. And the main tool is a hist aground on to help explain what the hissed a gram is actually telling you. I've enlisted the help of Thomas the Tank engine. So what is the history Graham actually telling us? Well, the HIST Graham is just a bar chart. Along the horizontal axis, you have shades of gray from black on the left to pure white. On the right, on the vertical axis is a number of pixels that have that particular shade of gray. Now they'll tell you that the perfect hissed a gram should be in the shape of a bell in that it has a range of tones from black to white. The thing is that there is no such thing as a perfect hissed a gram, because history am cannot be read in isolation. It has to be read in conjunction with what you're photographing now, in this particular scene, as we can see that we actually do have a range of tones. We have quite a lot of mid tones in the blues and the reds. We have some white...

s in the very front. We have some blacks in the front of the tender. We also have a nice like graze in the clouds and then along the connecting rods and the coupling rods. I have some dark rates. So in this particular scene, I would expect to see a history Graham that was very much representative of that bell shape that we often talk about. But what happens if you were photographing, for example, a pile of coal in a big pile of coal? There are no light tones. There are no whites. There are no light grays or no medium graves, so you wouldn't expect to see that classic bell shaped hissed a gram in a big pile of coal. There are just dark grays and blacks, so in this sense you'd expect to see the hissed, a gram completely skewed over to the left hand side. So the hissed a gram has to be read in conjunction with the scene that you're photographing. What you have to do is a photographer is try and match the tones in the scene with the tones in your hissed a gram. Whether it is a match, then that is an indication of a faithful exposure where there isn't a match. If the hissed a gram is skewed either to the right or to the left compared to the scene, then that is an indication of either overexposure or under exposure. And that's when you have to make a change, I don't know.

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Ratings and Reviews

mark jacobson

What a marvelous course! What a marvelous teacher! When I went to college, my father would always ask me about my professors, more than the courses themselves. He was passionate about learning and although too busy with earning an income to go beyond an undergrad degree, continued to read 50 books a year. I still remember how he'd get almost visibly excited when I'd tell him about some special professor who taught with such enthusiasm and, more than just passion, evident delight and joy in the subject. 'Ah they're the best, son. How wonderful you have such a teacher." Well, he passed away decades ago but if he were still around I'd get a kick out of telling him about Chris Weston, the 'Prof' of this course. He's one of the very special ones: a teacher who's loved and lived his vocation--his avocation--since he was a boy--and still is as excited about it now as he was then. The result: a course that seems to be more a labor of love--of pouring far more energy and thought into the details then one typically finds in these courses--than anything else. Bravo Chris! I'm already on to your next one.


Chris is an amazing instructor who dissects theory giving amazing analogies that bring concepts to life. I have rarely been able to sit through most video course for more than a half-hour but watched this one from beginning to end. A good refresher course if you've been away from the camera for awhile or there are some concepts that still illude you. I highly recommend this course and look forward to watching his others. Thank you for the clarity and great explanations.

Sky Bergman

This was an amazing class. I have looked at a number of basic photography classes. This one was by far the best I have seen. Chris is an exceptional teacher. He breaks things down into digestible information and then inspires you to be creative. Thank you!

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