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Exposure and How It Works - A Beginner's Guide
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Sep 12, 2017 00:59:15   #
maren
 
rmalarz wrote:
I’m contributing this article to explain exposure for those beginning your exploration of photography. It is key to understand some very fundamental principles in order to produce an optimum quality image. One typical reference is constantly made to a time honored device, The Exposure Triangle. That seems to introduce a bit of confusion. Let’s simplify this entire concept with something with which almost everyone has, at least, a passing acquaintance, something that is dynamic in nature. However, before we start, let’s get a couple of definitions established. So we are all discussing the same concepts across the board, let’s set a couple of descriptions for the purpose of this article. These are not my arbitrarily made up definitions. They are definitions accepted throughout the photographic world.

Exposure
In photography, it’s how much light is allowed through an opening and for how long. That’s it. And, it’s that simple.

Photographic Exposure
This involves the above definition, but includes a light sensitive material (film or sensor) upon which the light coming through a lens, or pinhole, is allowed to fall.

It is understood that the reader of this article is familiar enough with the settings of their camera where it comes to ISO, Aperture, and Shutter Speed. The idea is to balance the amount of light with a duration to effectively expose the light sensitive material optimally. That is all we are trying to accomplish.

So, with balance being brought into the discussion, let’s imagine a scale, very much like the Scales of Justice. We have a beam from which is suspended two platforms, one from either end. The idea is that the ideal exposure will occur when the balance is perfectly level.

We have a set of weights that go on the left side of the balance, and only on the left side. These weights are labeled ISO. They are in values of 50, 100, 200, 400, 800, 1600, etc. Weights for the other side of the scale are labeled f/1.4, f/2.8, f/3.5, f/4.6, f/5.6, etc. and 1, 1/2, 1/4, 1/8, etc. The weights on this side are designed to be used together in some combination.

We now have all the tools to determine a means to associate the three weights. If the beam is perfectly horizontal, we have the correct settings for an optimum exposure. For example, let’s say we have a scene that requires a setting of f/11 at 1/125 of a second to balance an ISO of 100. If we choose to change the f/11 weight to f/5.6, we are either going to have to change the 1/125 weight to another value to make the scale balance again. In this case, the 1/125 weight would have to be replaced by one of value 1/500.

There is a one to one ratio in the manner in which the right hand weights work. As we saw in the above example, we changed the f/stop weight 2 units, f/11 -> f/8 ->f/5.6, we had to change the associated weight by two units, 1/125 -> 1/250 -> 1/500, as well.

If we change the left hand side of the scale, we are going to need to change one or both of the right hand scale to keep things in balance. It’s all that simple. Once this simple concept is understood one can see that exposure becomes a system management situation. Understanding the systems completely will aid in making consistently better exposures.
I’m contributing this article to explain exposure ... (show quote)




Thank you so much for taking the time to post your article. I have been studying that exposure triangle and trying to read anything I could find to explain it. No matter what I read, I always had questions. I knew the general idea-----that if you change one of the three elements making up the correct exposure, you had to modify one of the other two to adjust. I had never read a more clear example of balancing the iso with the (f #'s PLUS the shutter speed). I loved the way you explained it. It finally clicked in my brain. Thank you. I can now go and practice with a much better understanding of what I am doing. You helped to remove some of the fear factor out of M-A-N-U-A-L.

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Sep 12, 2017 02:09:37   #
Shooting the ..it Loc: The High Desert of Oregon
 
From a newbie, thank you all for the simplified version of something I was not understanding. As soon as I read it, i grabbed my camera and read it again. It was like a light turning on. I look forward to future posts.

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Sep 12, 2017 04:04:11   #
dyximan
 
I too enjoyed the article, and understand the one to one ratio. And I am curious would your exposures be based on what the camera thought it should be? Or where your preference as to the final exposure should/could be? Or am I missing the point and this was simply an analogy of how to maintain a particular exposure. As I found myself trying to under expose my photos a little bit because I like a little darker color colors, or I guess what would be considered under exposed. But that may be a discussion for another day thanks for the info nice article
.

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Sep 12, 2017 06:02:49   #
nervous2 Loc: Provo, Utah
 
rmalarz wrote:
I’m contributing this article to explain exposure for those beginning your exploration of photography. It is key to understand some very fundamental principles in order to produce an optimum quality image. One typical reference is constantly made to a time honored device, The Exposure Triangle. That seems to introduce a bit of confusion. Let’s simplify this entire concept with something with which almost everyone has, at least, a passing acquaintance, something that is dynamic in nature. However, before we start, let’s get a couple of definitions established. So we are all discussing the same concepts across the board, let’s set a couple of descriptions for the purpose of this article. These are not my arbitrarily made up definitions. They are definitions accepted throughout the photographic world.

Exposure
In photography, it’s how much light is allowed through an opening and for how long. That’s it. And, it’s that simple.

Photographic Exposure
This involves the above definition, but includes a light sensitive material (film or sensor) upon which the light coming through a lens, or pinhole, is allowed to fall.

It is understood that the reader of this article is familiar enough with the settings of their camera where it comes to ISO, Aperture, and Shutter Speed. The idea is to balance the amount of light with a duration to effectively expose the light sensitive material optimally. That is all we are trying to accomplish.

So, with balance being brought into the discussion, let’s imagine a scale, very much like the Scales of Justice. We have a beam from which is suspended two platforms, one from either end. The idea is that the ideal exposure will occur when the balance is perfectly level.

We have a set of weights that go on the left side of the balance, and only on the left side. These weights are labeled ISO. They are in values of 50, 100, 200, 400, 800, 1600, etc. Weights for the other side of the scale are labeled f/1.4, f/2.8, f/3.5, f/4.6, f/5.6, etc. and 1, 1/2, 1/4, 1/8, etc. The weights on this side are designed to be used together in some combination.

We now have all the tools to determine a means to associate the three weights. If the beam is perfectly horizontal, we have the correct settings for an optimum exposure. For example, let’s say we have a scene that requires a setting of f/11 at 1/125 of a second to balance an ISO of 100. If we choose to change the f/11 weight to f/5.6, we are either going to have to change the 1/125 weight to another value to make the scale balance again. In this case, the 1/125 weight would have to be replaced by one of value 1/500.

There is a one to one ratio in the manner in which the right hand weights work. As we saw in the above example, we changed the f/stop weight 2 units, f/11 -> f/8 ->f/5.6, we had to change the associated weight by two units, 1/125 -> 1/250 -> 1/500, as well.

If we change the left hand side of the scale, we are going to need to change one or both of the right hand scale to keep things in balance. It’s all that simple. Once this simple concept is understood one can see that exposure becomes a system management situation. Understanding the systems completely will aid in making consistently better exposures.
I’m contributing this article to explain exposure ... (show quote)


Great article Robert. Like Grace, I too took the liberty of copying it to a Word Document so I can share it with my wife, children, grandchildren when I explain the camera settings. Now in your next article if you could include a paragraph about the concept of when to use a fast shutter speed and large f-stop or aperture and when to use a slower speed and a small f-stop or aperture I will add it to the current article. I could explain but you do it in such a clear and concise manner. Again, thanks for your post.

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Sep 12, 2017 07:24:24   #
rmalarz Loc: Tempe, Arizona
 
Steve, maren, Shooting the ..it, dyximan, nervous2, thanks for reading this and commenting. Now that we've got some folks off to a good start, we're going to move on to some more advanced concepts.

nervous2, you've brought up some good points. However, they aren't directly related to exposure. They are side effects of exposure settings and I'll address them very soon.
--Bob

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Sep 12, 2017 09:10:25   #
frankraney Loc: Clovis, Ca.
 
Aeneas wrote:
The competence and effort you put into your original post is much appreciated.
It represents the best of Ugly Hedge Hog and is of maximum value to many who use this site.



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Sep 12, 2017 09:14:47   #
Franku Loc: Wallingford, PA and Parrish, Fl
 
Well done!

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Sep 12, 2017 09:40:18   #
a6k Loc: Detroit & Sanibel
 
Steve3265 wrote:
Bob,

First of all a great way to explain things and a great example. I would like to ask though, when I started years ago I worked with film of course and my photo teacher would not allow us to use any auto settings. We were taught using a light meter how to make our adjustments. My issue today is I have a very nice mid-range DSLR and though it has a built in light meter it just isn't the same as using a manual. Any suggestions beyond going back to a hand held unit?


I know you asked the OP but let me cut in for a moment. Your camera has a TTL meter (through the lens) and most have the ability to confine the reading to "spot" or some similar term. Further, most modern cameras will show you the ISO, shutter and lens openings; some show EV. In other words, you already have a very good hand held meter.

I won't go into a wordy explanation of how to use it in that context because that would be to hijack the thread. It's a very good thread as it is.

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Sep 12, 2017 12:29:39   #
cambriaman Loc: Central CA Coast
 
Excellent tutorial. I am sure quite a few of the UHH'ers got some value from your work! Thanks!

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Sep 12, 2017 12:33:34   #
rmalarz Loc: Tempe, Arizona
 
Thanks, cambriaman. Your comment is appreciated.
--Bob
cambriaman wrote:
Excellent tutorial. I am sure quite a few of the UHH'ers got some value from your work! Thanks!

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Sep 12, 2017 12:47:56   #
lmTrying Loc: WV Northern Panhandle
 
nervous2 wrote:
Great article Robert. Like Grace, I too took the liberty of copying it to a Word Document so I can share it with my wife, children, grandchildren when I explain the camera settings. Now in your next article if you could include a paragraph about the concept of when to use a fast shutter speed and large f-stop or aperture and when to use a slower speed and a small f-stop or aperture I will add it to the current article. I could explain but you do it in such a clear and concise manner. Again, thanks for your post.
Great article Robert. Like Grace, I too took the ... (show quote)


Good questions! I'm sure Bob is intending to cover them, so I will not. However, I'm willing to bet that a lot of people were wondering the same things and are now glad that you did ask the questions. Keep asking questions, that's the way we ALL learn.

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Sep 12, 2017 12:59:16   #
Tikva Loc: Waukesha, WI
 
I appreciate this article and every other article, video and book I read on exposure. When I'm working with my camera, I have to fiddle around with it to get it set right. It still doesn't come naturally. I sometimes think that I am just having a problem learning new things (age 74) at least learning them quickly. I am getting the hang of it, I do shoot in manual mode and my shots are improving. My cat is my main model (having problems getting outside to do much shooting lately). The only problem I have with her being my model is that she is pure white. I find it difficult to get the amount of detail in her fur that I think I should be getting.

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Sep 12, 2017 13:16:28   #
GAS496 Loc: Arizona
 
Bob,

This is a great post. By using this information there is little doubt getting the exposure as correct as possible on the chip or film in camera should make post adjustments that much easier either on the computer or in the darkroom. Bravo!

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Sep 12, 2017 13:33:59   #
rehess Loc: South Bend, Indiana, USA
 
Tikva wrote:
I appreciate this article and every other article, video and book I read on exposure. When I'm working with my camera, I have to fiddle around with it to get it set right. It still doesn't come naturally. I sometimes think that I am just having a problem learning new things (age 74) at least learning them quickly. I am getting the hang of it, I do shoot in manual mode and my shots are improving. My cat is my main model (having problems getting outside to do much shooting lately). The only problem I have with her being my model is that she is pure white. I find it difficult to get the amount of detail in her fur that I think I should be getting.
I appreciate this article and every other article,... (show quote)
Getting "detail" is not the same question as getting good exposure. With my buddy, a black cat, I've found that using flash shows her contours better than using natural light does, even when the image has the same brightness {exposure}

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Sep 12, 2017 13:45:18   #
rmalarz Loc: Tempe, Arizona
 
Thank you very much, Frank. Hopefully, you'll enjoy the follow up article, as well.
--Bob
Franku wrote:
Well done!

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