# First brief photography article on "the exposure triangle". Thoughts?



## Katsi (Feb 26, 2015)

Hdhhd


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## photoguy99 (Feb 26, 2015)

Um. Where's the article? Did the moderator edit it out?


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## tirediron (Feb 26, 2015)

It's coming... just a minor misunderstanding of forum policies!


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## Katsi (Feb 27, 2015)

tirediron said:


> It's coming... just a minor misunderstanding of forum policies!


Cheers Tirediron!!


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## Designer (Feb 27, 2015)

Katsi said:


> *Sorry to anyone that looked at the post and miss the article. I didn't realise I couldn't post I direct link.*


This is news to me.


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## Reedforum (Mar 5, 2015)

It's good that someone has written an easy to understand explanation of terms that are rather important in this field. More often than not, it's easy to get lost in definitions and numbers. Thanks for taking the time to put your knowledge onto paper. It will help a lot of people if they take the time to read through it.


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## Katsi (Mar 5, 2015)

Thanks Reedforum!! That means a lot. Glad you liked it. That was my aim!


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## gsgary (Mar 5, 2015)

There is one part that is wrong, in shutter speed 5th paragraph increase shutter speed lets more light in [emoji107]
Also you mention raising iso gives you noise or grain, it only gives you noise


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## KmH (Mar 5, 2015)

Also, and depending on some other factors like image sensor size, from f/11 or so towards even smaller lens apertures blur starts increasing again because of diffraction. 



> Shutter speed is simply the length of time that the camera’s shutter is open for. The longer it is left open for the more light that enters the lens.


 Yes, the shutter speed is "the length of time that the camera’s shutter is open for".

The amount of light entering the lens doesn't change if shutter speed is changed. 
How much light comes out the rear of the lens is determined by the lens aperture, the design of the lens, and how much light is lost in the glass elements in the lens.


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## Ysarex (Mar 5, 2015)

*Get it proofed for grammar and spelling. It needs it.*_

Aperture is also referred to as the “f stop”, if you can’t find the aperture on your camera it is the number with the “F” in front of it.
_
The aperture is the opening in the lens. An f/stop is a value measurement and is written like this: f/2.8. There is no reason for it to be in quotes. It should be written out and not referred to as "F" or 'f' 

_The larger the aperture the more “open” the lens is and the more light that is let into the lens._ 

Your topic is the exposure triangle. You wrote paragraphs about the aperture but only the above sentence address its role in exposure. Your readers will miss that entirely; as far as your article is concerned the aperture has nothing to do with exposure.

_This is true up until 1/1” or 1 second. In most DSLRs it is possible to have a shutter speed of up to 30 seconds, represented as 1/30”._

1/30 does not represent 30 seconds it represents 1/30 second.

_You still want your photograph to be correctly exposed however and so you would increase the ISO, making your camera’s sensor more sensitive to light and therefore increasing the exposure of your image._

Increasing ISO does not make your camera's sensor more sensitive to light.

*Get it proofed for grammar and spelling. It needs it.*

You really did not address the topic of your article well: the exposure triangle. You wrote about the lens aperture and the shutter and ISO values but you didn't make the article a cohesive explanation of using those tools in the task of setting an exposure.

Joe


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## Designer (Mar 5, 2015)

Katsi said:


> The terminology that refers to aperture can often confuse people. This is because it is said that a small ‘f’ value is a large aperture and a large ‘f’ value is a small aperture… confused?


You might be confused by this, but your "explanation" is unlikely to clarify the point for your readers.

The aperture value is a fraction, i.e.: 1/16.  A larger denominator represents a SMALLER fraction, corresponding to a SMALLER aperture.  Use the correct terminology and you will be most of the way toward explaining this better.


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## Designer (Mar 5, 2015)

(update)  I just checked out 6 more explanations and he is using some of the same terminology as the others are using.  

Good luck with your blog, Katsi!


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## tecboy (Mar 5, 2015)

"The other thing to realise however is that the more you increase your shutter speed the more light you let in."

That is not correct. right?

The group of fireflies is not the right analogy for higher iso.   Is the "higher iso" like an amplifier to increase more power to get more sensitive to the light?


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## Ysarex (Mar 5, 2015)

Katsi said:


> Hey Joe! (great song)
> 
> As I said above I have since seen people describe ISO as increasing your cameras sensitivity to light and I have also seen people dispute it and argue it. Obviously someone is wrong and in this case I'm assuming it's me!! haha. I will try my best to come up with a more accurate and easily digestible description for ISO.



Yes that one causes a lot of confusion. Back in the film era a higher ISO film *was* more sensitive to light and that understanding has become a misunderstanding in the digital era. Nothing here to argue about; facts are simple and clear. The  light sensitivity of a digital sensor is fixed in manufacture and can't be altered -- period. So when you raise the ISO on a digital camera something else must be happening. Think it through. And why does it matter?

Joe


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## KmH (Mar 5, 2015)

Katsi said:


> Also again, I am aware that increasing the shutter speed doesn’t physically allow more light into the camera, I was trying to keep the concept simple and described it incorrectly, but I suppose it is better to describe as perhaps… “the longer the shutter speed the more time the cameras sensor is exposed to light”?


Yes, that better explains what a longer shutter speed does.

Using the word 'increasing' when applied to shutter speed, because we are usually using fractions of a second, many will mistake 1/1000 as an increase from 1/500 when the opposite is true. 1/1000 is a 2x smaller number than 1/500 is.


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## tecboy (Mar 6, 2015)

Katsi said:


> I'm not entirely sure if an analogy can be correct or not. It is what it is, an interpretation of a concept.



Your interpretation of a concept is unclear.  You are comparing the number of fireflies as a value of ISO.  Firefly is light and what is this has to do with ISO?


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## gsgary (Mar 6, 2015)

I think if you teamed up with Ken Rockwell it would make for a good read


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## Designer (Mar 6, 2015)

KmH said:


> Katsi said:
> 
> 
> > Also again, I am aware that increasing the shutter speed doesn’t physically allow more light into the camera, I was trying to keep the concept simple and described it incorrectly, but I suppose it is better to describe as perhaps… “the longer the shutter speed the more time the cameras sensor is exposed to light”?
> ...


Hmm.. More of those pesky fractions.  (haha)


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## Designer (Mar 6, 2015)

Katsi said:


> Can you explain what terminology I am using that others are also using?


You are practically quoting some of the same articles I read yesterday, even using some of the same phrasing.

My post was not intended to embarrass you nor to accuse you of plagiarism, but merely to point out that your limited ability to explain the concept is hindered by your limited research.  

For me to list those passages is a waste of my time, but anyone who wishes to point them out is welcome to do so.


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## The_Traveler (Mar 6, 2015)

Without attempting to be mean or cruel, although it may sound that way, I find this article as written to be very, very confusing.
The analogies are so confusing as to lead to the wrong impression.

For example:


> "When I was trying to understand aperture I was told to remember it like this:
> 
> When you are a child aged 2 (small number) you see only what’s in front of you, you have a shallow depth of field (more blur). When you have a small ‘f’ value, e.g. f2.8 (small number), you also have a shallow depth of field (more blur).
> 
> When you get older (larger number) more of your surroundings come into focus, you have a deeper depth of field (less blur, more in focus). When you have a larger ‘f’ value, e.g. f22 (large number), you also have a deeper depth of field (less blur, more in focus)"



This mixes up the concept of being able to see close up or far away with that of depth of field and someone with no other knowledge could easily come away with an impression that a large f stop means that things up close are in focus.

TBH, I would dump this version completely and start again.


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## gsgary (Mar 6, 2015)

The_Traveler said:


> Without attempting to be mean or cruel, although it may sound that way, I find this article as written to be very, very confusing.
> The analogies are so confusing as to lead to the wrong impression.
> 
> For example:
> ...


I don't think they have had a camera long


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## yassef622 (Mar 6, 2015)

مافي عرب


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## Ysarex (Mar 6, 2015)

Katsi said:


> The_Traveler. The more this thread goes on the more I think that is exactly what I will do. It seems maybe writing isn't my thing. I was just trying to write an article for something to do and hope that it would cement my learning a bit, which in many ways it has.
> 
> That was the way that aperture was explained to me and it is clear in my head, it made it click for me. But hey ho. Maybe it is confusing. I will scrap it. Its not worth it for me, I just seem to get it wrong and then get rude, condescending messages because of it. I was just enjoying trying to write for the first time but people are very quick to judge and be mean. I certainly didn't intend to rip off people's work. I still don't feel like I have done that.
> 
> ...



Peace. And good for you that you came back with this response. It's very hard to put your work out there for criticism and it's tough hearing that what you did isn't as good as you had hoped. For the record: rude and snide comments were uncalled for.

Joe


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## Designer (Mar 6, 2015)

Katsi said:


> I certainly didn't intend to rip off people's work. I still don't feel like I have done that.


There is no intention of meanness on my part.  I did not accuse you of plagiarism.  

I think your attempt is to be applauded, and most of the comments here seem to be directed toward making your article better.

Please be aware that this is probably one of the most complicated aspects of photography that is related to the technology.  There have been entire books written on this, so I think your attempt at a shorter version is entirely worthwhile, and I wish you luck.


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## The_Traveler (Mar 6, 2015)

yassef622 said:


> مافي عرب



OK, I give up.
What does this mean?


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## Bjoern.asbjoernsen (Mar 6, 2015)

Pedagogic and explainatory, one thing I think you forgot is that one f stop is equal to one step in exposure time.  f: 5.6 and f.eks 1/60" will be f:4  1/125" and the other way if you need better dof. 

Sent fra min SM-T210 via Tapatalk


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## levinj (Mar 6, 2015)

There's an old saying "Tallest trees catch the most wind" Don't give up. This is your way of looking at it. Take lots of pics, write lots and you'll improve at both.


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## dennybeall (Mar 7, 2015)

Now you see why it's so hard to get folks to write up things for the net.  (rest deleted prior to posting.....)


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## Derrel (Mar 7, 2015)

As far as explaining aperture, one analogy I have used to help people is to tell them that the f/stops represent fractional values, of how wide the light-admitting aperture is, and I actually use three coins: a Kennedy half dollar, a Washington Quarter, and a Roosevelt dime, representing f/2, f/4, and f/11 (rounded from f/10). It's an easy-to-understand concept...fractional value...it makes it super-easy to remember that when the lens is, "1/16th of the way open, the hole that lets in the light is teeny-tiny."


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## eleni.karaolani (Mar 23, 2015)

I am a beginner in photography and although I knew some things , your article made things more clear!!! Thanx!!


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## Tim Tucker (Mar 30, 2015)

Well, kind of an oversimplification that misses the main aspects and relationships between shutter speeds, focal length, aperture and distance.

I would tackle this as three separate subjects much as Ansel Adams does in his book "The Camera".
F-stop is simply the effective aperture of the lens described as a ratio of it's focal length, hence the f. f4 or 1:4 on a 100mm lens simply means it has an effective aperture of 25mm or 1/4 of the focal length f. In an ideal world all lenses transmit the same amount of light onto a sensor at the same f-stop. Depth of field is affected by aperture, but also considerably more by focal length and distance from the subject.

Shutter speed is not the only or even the main contributor to reducing motion blur. Again focal length and distance from the subject play a vital role. It is about how far across the sensor the moving part of the image travels while the shutter is open.

I also have a big problem with the idea of an exposure triangle. It suggests that you use ISO as an exposure tool so you can set the aperture and shutter speed you want, this is a big mis-understanding of it's role and how it affects the image.
Aperture, shutter speed and ISO are all logarithmic scales. With aperture and shutter speed each increase of one stop doubles the amount of light hitting the sensor for any given luminance value. This is not the case when you adjust the ISO setting. to see how this works in it's simplest form think about the luminance as arbitrary units from shadow values to highlights.
We start with no light, a value of 0. If we then assign a value of 1 unit for the amount of light that makes the first measurable tone on your sensor then for each successive increase of one stop on shutter speed or aperture the amount doubles so the units are:

1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024.

This represents a realistic and usable DR of 11 stops and is the luminance values for the tones from black to white in your image using our arbitrary values. You will notice one very important thing here:
The difference in luminance between the deepest shadows (1 to 2) is 1 unit in 1024 or 0.1% of the luminance of the white values, whereas the difference in your highlights say between 256 and 512 is 25% of the luminance, yet both of these increments represents a difference of 1 stop.
A simple model of what happens when you increase ISO is that you progressively under-expose you image then amplify the signal. So an exposure at ISO800 is 3 stops under exposed and so you shift the values down the scale by 3 steps. Your shadow values that are 3 stops under exposed are all now below 0.2% of the amount of light the sensor can record.
You can see now that amplifying such small differences in values contributes to poor separation of tones and a lot of noise. You effectively decrease the DR of the camera when you increase the ISO setting.

Hope this helps some.


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