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I am interested about studying exposure. I went through a few tutorial (as a beginner of DSLR photography) but I find them generally lacking of details.

I have a background in engineering, physics and math. Is there a more in-depth introduction to exposure, specifically for DSLRs? Not that I am necessarily interested about seeing equation, but I feel like do not know enough in this matter.

Ideally, I would like to read a book that explains such matter from a more technical standpoint, possibly with examples.

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  • \$\begingroup\$ Can you explain a little more about what you mean by "such matter" in that last sentence? Are you looking for a book that helps you know how a camera works, or a book to help you make exposure decisions? \$\endgroup\$
    – mattdm
    Commented Jan 10, 2013 at 13:36
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    \$\begingroup\$ I'd also add: we've got a wealth of material on this site, both on the workings and the application. I'd start by reading questions in the exposure tag, followed by aperture, shutter-speed, and iso. When there seem to be gaps or you feel like you're not getting something, ask a new question. \$\endgroup\$
    – mattdm
    Commented Jan 10, 2013 at 13:40
  • \$\begingroup\$ The principals are pretty simply but the recipes are not. You may want to look for patents by Nikon, Sony, Pentax, etc. I understand those are not written to be understood easily though! \$\endgroup\$
    – Itai
    Commented Jan 10, 2013 at 14:23
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    \$\begingroup\$ I think you might particularly like the "Exposure Cuboid" explanation I give as an alternative to the Exposure Triangle. It's a more technical (and mathematically correct!) explanation for how the factors affecting exposure work together. \$\endgroup\$
    – mattdm
    Commented Jan 10, 2013 at 14:24
  • \$\begingroup\$ Are you interested in: A) How the sensors capture data, how the cameras interpret that data, is the response to light linear or is there a curve, etc.? B) How the light meters in cameras are constructed, calibrated, what algorithms they use when multiple areas are read, etc.? \$\endgroup\$
    – David Rouse
    Commented Jan 11, 2013 at 16:25

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One of the most recommended photography books is Bryan Peterson's Understanding Exposure

If you haven't read it, I would suggest that book as a start.

What are the technical aspects you're after? Peterson's book covers the exposure triangle, metering, use of grey cards, etc.

For more technical and in depth coverage of light, read Light: Science and Magic, which is generally recognised as the "bible" of lighting. Much of the book covers how to photograph various surfaces such as glass and metals, but it also covers absorption and reflection, inverse square law and so forth.

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    \$\begingroup\$ I think Peterson's book is the opposite of technical. It's practical (which is why people like it) but doesn't go into physics or math in any meaningful way. \$\endgroup\$
    – mattdm
    Commented Jan 10, 2013 at 13:25
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There really isn't that much to know. Consider a film camera, which used film of a fixed ISO/ASA rating, say 100.

Proper exposure by the sunny 16 rule says that bright sun lit scenes on a sunny day need F16 at 1/100. Its by definition, the chemical makeup of the film controls its sensitivity and an ASA film number is the shutter speed by the Sunny 16 rule.

The F-stop is simple the mathematical ration of iris size to focal length. The shutter speed is simply seconds its open.

You want the product of the shutter speed times the F-number to be a constant

F32 @ 1/50
F16 @ 1/100
F8 @ 1/200
F4 @ 1/400

Now for traditional reasons, the shutter speeds are not quite powers of two. So you get to use the closest
F32 @ 1/50
F16 @ 1/125
F8 @ 1/250
F4 @ 1/500

All you are doing is allowing a constant number of photons into the sensor/film

All sensors and/or film have some latitude, you can over or under expose them a stop or two and get the image. So you expose for most of the image, and some parts are over or under exposed and that gives tone and depth to the image.

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  • \$\begingroup\$ I don't think this really answers the question. Not only is it not a book recommendation, but it's also a quick, non-technical gloss over the subject at a high level, which strikes me as somewhat ironic. \$\endgroup\$
    – mattdm
    Commented Jan 12, 2013 at 15:14
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    \$\begingroup\$ You are of course entitled to think whatever you like. I believe that exposure is a simple concept. Its just arithmetic. If it wasn't simple, all the photographers in pre-computer times would have not been able to take any photos. \$\endgroup\$
    – Pat Farrell
    Commented Jan 12, 2013 at 16:31
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    \$\begingroup\$ It's simple, but with a lot of underlying depth. This question is looking for the depth, not just the simple. \$\endgroup\$
    – mattdm
    Commented Jan 12, 2013 at 16:35
  • \$\begingroup\$ In pre-computer times, a considerable amount of photographers spent a considerable amount of time setting up for a single shot...metering, measuring, correcting, over and over until they had everything exactly as they needed, and fully understood the dynamic range of their scene in order to be capable of properly exposing without losing detail or tonal range. There is even a system for that manual process, the Zone System, and it is not exactly as "simple" as you are here indicating, @Pat. I do believe the OP is asking for some depth, beyond the simplistic surface of what "exposure" is... \$\endgroup\$
    – jrista
    Commented Jan 14, 2013 at 17:29
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Not a book, but for a technical overview of exposure I recommend the wikipedia entry on Exposure value.
Briefly, you have some level of light in the scene, called LV (light value or luminance value), and a combination of camera settings - shutter speed, aperture and ISO - called EV (exposure value). They are measured on the same scale, and when LV in the scene equals EV on the camera we have a correct exposure.
This is "correct exposure" in the rather narrow technical sense of making a gray card show up as 18% gray in the image. This is how camera light meters work: They assume that you want everything in the scene to average out to 18% gray, and will give a night photo the same average brightness as a day photo if you let them.

You will probably want to know about dynamic range as well, the ratio between the brightest and darkest luminance a sensor can capture in a single exposure. Many other fields measure dynamic range in dB (log 10 scale), while in photography we most commonly use stops (1 stop = 1 EV, log 2 scale).
Many scenes will have a higher dynamic range than the sensor can capture; then you'll need to decide which parts you are willing to sacrifice.
Alternatively, look into more advanced topics like HDR or exposure fusion, which combine several pictures of the same scene, taken with different EV settings, into a single image.

The Zone System is based on EV and dynamic range: You pick a single spot in your scene and decide how bright or dark you want it to appear in the photo, and adjust the EV from the light meter reading accordingly.
The question "What is Ansel Adams' Zone System" has a nice overview with example pictures.

As far as the technical aspects of exposure go, that's pretty much it.

There are also various effects of choosing different shutter speed/aperture/ISO combinations for the same exposure, but those are different topics. (Primary keywords: Motion blur, depth of field and high-ISO noise.)

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