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Exposure and How It Works - A Beginner's Guide
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Sep 11, 2017 07:37:36   #
GLKTN Loc: TN
 
Thanks Robert. I am a beginner and have been reading many and varied explainations to get a better grasp. I believe it is necessary because there is a huge variety of experience ability and knowledge. It takes some a while to grasp the exposure triangle. As an example, I am taking a basic Principals of Photography given by my local camera club. A lady taking the class the third time just got that the f-stops were on the lens not in the camera. Not everyone has the same level of ability and need reinforcement. Thanks again.

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Sep 11, 2017 07:39:15   #
The Villages Loc: The Villages, Florida
 

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Sep 11, 2017 07:58:40   #
Mundj Loc: Richmond TX
 
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 for taking the time to write and share this post.
👍👍👍

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Sep 11, 2017 08:09:15   #
Rineal Loc: Copake NY
 
Thanks for this clear explanation - it is a great way to explain it!
Richard

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Sep 11, 2017 08:09:20   #
jimcrna Loc: indiana/florida
 
hi and thank you. great analogy..appreciate your time to explain to us in the novice group..

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Sep 11, 2017 08:14:25   #
Mary Kate Loc: NYC
 
rehess wrote:
This is a fine explanation, but I don't understand why it is necessary.

In June 1969 I used college graduation money to purchase my first adjustable camera, a Yashica rangefinder camera. I glanced through the instructions, loaded a roll of film, set dial to match "ASA" number on film box, and took some properly exposed pictures. To take a picture, I moved a lens dial to match EV reading from the enclosed light meter; then I had the choice of turning another dial which changed the shutter speed {on dial} / aperture {in little window} combination called for.

This process was slightly more complicated than "P" mode today, but roughly comparable.
This is a fine explanation, but I don't understand... (show quote)


Perhaps because there may be some who are not as experienced as you. I thought it was well written and involved something important.

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Sep 11, 2017 08:29:58   #
royden Loc: Decatur, GA
 
Robert, you make me want to say a hogger. Was thinking of quitting because of bc...bull crap. Thanks.

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Sep 11, 2017 08:37:12   #
Notorious T.O.D. Loc: Harrisburg, North Carolina
 
Good article. I think in today's digital environment it needs to treat ISO as a bigger component of the equation. Certainly in film days one normally set ISO or ASA and adjusted only shutter speed and aperture to get a proper exposure. I think that is why many photography programs still start teaching students with film cameras. Today we can vary ISO just as easily as the shutter speed and aperture with our digital cameras. Understanding these fundamental relationships is key to learning to shoot pleasing images for sure.

Best,
Todd Ferguson

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Sep 11, 2017 08:57:18   #
DaveC1 Loc: South East US
 
Very good introduction to exposure.

It might be useful to talk about intentionally under or over exposing the overall photo in order to draw the viewers attention to portions of the photo that the photographer intended to draw the viewer's eye to. Bright sky with backlit subjects come to mind as an example, realizing that most digital cameras try to handle this automatically with varying degrees of success.

This is purely a suggestion for future articles.

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Sep 11, 2017 09:07:08   #
rmalarz Loc: Tempe, Arizona
 
As I stated in the intro to the article, there are some assumptions made about the reader being familiar with certain aspects of their camera. I appreciate your taking time to read the article and comment.
--Bob
rook2c4 wrote:
Your article is certainly accurate. How effective it will be to teach a typical beginner, I'm not sure. All those values peppered throughout the text may be confusing to a student. I suppose it will depend on the effectiveness of the lesson before it, which would need to explain what aperture, shutter speed and ISO are and what the values mean.

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Sep 11, 2017 09:08:04   #
rmalarz Loc: Tempe, Arizona
 
Thanks for the thumbs, Gene, they're much appreciated.
--Bob
Gene51 wrote:

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Sep 11, 2017 09:08:55   #
rmalarz Loc: Tempe, Arizona
 
Thanks, Rongn.....
--Bob
Rongnongno wrote:
Good analogy.

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Sep 11, 2017 09:10:32   #
rmalarz Loc: Tempe, Arizona
 
Thanks for commenting, rehess. I guess my motivation was based on a number of posts that indicated some need for clarity on how aperture, shutter speed, and ISO are related.
--Bob
rehess wrote:
This is a fine explanation, but I don't understand why it is necessary.

In June 1969 I used college graduation money to purchase my first adjustable camera, a Yashica rangefinder camera. I glanced through the instructions, loaded a roll of film, set dial to match "ASA" number on film box, and took some properly exposed pictures. To take a picture, I moved a lens dial to match EV reading from the enclosed light meter; then I had the choice of turning another dial which changed the shutter speed {on dial} / aperture {in little window} combination called for.

This process was slightly more complicated than "P" mode today, but roughly comparable.
This is a fine explanation, but I don't understand... (show quote)

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Sep 11, 2017 09:11:36   #
rmalarz Loc: Tempe, Arizona
 
Thanks, BJW. I'm glad you found this helpful. I appreciate you taking time to leave a comment.
--Bob
BJW wrote:
Very helpful.
Thank you.
BJW

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Sep 11, 2017 09:20:37   #
rehess Loc: South Bend, Indiana, USA
 
Mary Kate wrote:
Perhaps because there may be some who are not as experienced as you.
No, I was talking about the very first time I handled a camera that could be adjusted. I had zero experience with adjustments - not many numbers are less than zero.

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