# Exposure Triangle



## amolitor (Aug 2, 2012)

What is UP with this "exposure triangle" idiom? Every beginner's guide to photography web site seems to have picked this thing up, but it makes no sense to me. Don't get me wrong, I understand exposure just fine, thanks. It's the use of the triangle that's a mystery to me. At best it seems to capture the idea that "ISO, shutter speed, aperture are interconnected" which I can accomplish with the sentence "ISO, shutter speed, and aperture are interconnected" or with any number of graphical representations.

Is there something I am missing? If I, I dunno, imagine that the correct EV is a dot somewhere inside the triangle.. then when I adjust the shutter speed.. the dot.. I dunno, moves away from something and toward something else?

The triangle strikes me as a glib little bit of graphical crud that obscures the issue. Newbies stare at it, I imagine, and try to figure out what on earth a triangle has to do with anything.

Exposure is trivial, we don't actually need little mnemonic devices to teach it, and we CERTAINLY don't need anti-mnemonic devices like meaningless graphics.


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## JAC526 (Aug 2, 2012)

People like pictures man.

Don't give people too much credit.


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## SCraig (Aug 2, 2012)

amolitor said:


> What is UP with this "exposure triangle" idiom? Every beginner's guide to photography web site seems to have picked this thing up, but it makes no sense to me. Don't get me wrong, I understand exposure just fine, thanks. It's the use of the triangle that's a mystery to me. At best it seems to capture the idea that "ISO, shutter speed, aperture are interconnected" which I can accomplish with the sentence "ISO, shutter speed, and aperture are interconnected" or with any number of graphical representations.
> 
> Is there something I am missing? If I, I dunno, imagine that the correct EV is a dot somewhere inside the triangle.. then when I adjust the shutter speed.. the dot.. I dunno, moves away from something and toward something else?
> 
> ...



Yes, there is something that you are missing.  The geometric relationship of a triangle is that no single side or angle can be changed without making a compensating change to another side or angle.  The same exact relationship exists between shutter speed, aperture, and ISO.

If you don't like it then don't use it.  It's not going to stop others from teaching it that way though.


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## tirediron (Aug 2, 2012)

First of all, I would submit to you that exposure is NOT trivial; it is the most critical aspect of photography.  In fact, you could go far as to say that exposure is photography.  The use of the triangle stems from the fact that there are three separate components to exposure, and they are inter-related.  If you change one, then you have to change at least one other one.  

The interior space of the triangle is irrelevant, it's the legs that are important.  Assume that in situation 'X', ideal exposure is:  ISO 200, 1/250, and f8.  At that exposure, each leg is 6" long.  We decide for the sake of the image that we need to have a shutter-speed of 1/1000; when we dial that on, it makes that leg now 12" long and "breaks" the triangle.  Therefore we have to adjust the length of the other legs to compensate.

At the end of the day, if it doesn't work for you, don't worry about it.


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## tirediron (Aug 2, 2012)

Get outta my head Scott!


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## SCraig (Aug 2, 2012)

tirediron said:


> Get outta my head Scott!



Great minds think alike


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## pgriz (Aug 2, 2012)

Whatever gets the idea across...  Having people refer to the "Exposure Triangle" does not discombobulate me or impact my life in any way.  Although I suppose, for sake of accuracy, we need to define whether it is an equilateral triangle, or an isoceles triangle or an obtuse triangle... And whether the space is Euclidian or Gaussian.  Guess it doesn't matter if you use Powerpoint, which draws almost all trianges as equilateral, the easier it is to attach labels to the vertexes.  Meh.  Like "lines" of sight, and "square" meals, and "circular" reasoning.


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## amolitor (Aug 2, 2012)

Yes, yes, I get that it captures the idea that the three things are interconnected. My point is that it seems to capture nothing whatsoever ELSE.

It looks like a graphic that I ought to be able to use to calculate, or at any rate estimate.

tirediron says:

"we need to have a shutter-speed of 1/1000; when we dial that on, it makes that leg now 12" long and "breaks" the triangle"

which is fine except that: a) the ISO, shutter speed, and aperture are invariable shown at the corners, so which leg is it exactly that got twice as long? and b) When we've got that sorted out, what are we supposed to do with the other legs? Make them twice as long as well by doubling the aperture and ISO? Or do we adjust the opposing angle instead which is.. what? Does the triangle have to remain equilateral, what exactly does it mean when we double the length of a leg, are we making the aperture bigger or smaller?

It FEELS like it's a geometrical model of what's going on, and that the triangle somehow captures something, but it simply doesn't. You wind up in a maze of 'well, the shutter speed is the angle so when you halve the shutter speed you have to double the angle no wait you cut it in half and then you have to adjust the sides no wait the angles OR the sides or or or oh god what is going on here'.


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## Solarflare (Aug 2, 2012)

The three parameters ISO, Aperture, and Shutter Speed each have different properties.

Learning to know these properties helps to find the optimal values for these parameters for each picture.

ISO, you always want that at minimal value unless its completely unavoidable to raise it. If you have to raise it, it will introduce noise into your picture and limit all other parameters of your fotosensor, like dynamic range or color depth or resolution etc, as well.

Aperture, you want this very open if you need a small depth of field, like for a portrait. This also gives you the maximum light. However, if you want a very wide depth of field, you need to close it, massively reducing the available light.

Finally, Shutter Speed defines how much time will pass during taking your picture. If you just want to photograph a landscape, or some other static object, its not problematic. Just get a tripod and you can raise the shutter speed to seconds and minutes easily. In other cases, you want one specific shutter speed. For example for panning you need a very specific shutter speed that still allows to make the subject look sharp, but the background blurry, while you move the camera with the subject. Other times you want everything to be sharp. Then very low shutter speeds might be required, like 1/1000s and less.

So yeah, the exposure triangle is a very important to know about. If you take your picture with ISO 100 and f/2.8 will result in a very different picture from taking it with ISO 6400 and f/22.


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## amolitor (Aug 2, 2012)

Just as a for instance, suppose we forget ISO for the moment.

Imagine a graphic of a teeter-totter, a see-saw, or a balance scale. Label one side "shutter speed" and the other "aperture", and then write underneath it "keep the scale balanced to keep the exposure the same". Now we see clearly and unambiguously (assuming we have proper labels) that if we make the shutter speed faster, we must make the aperture wider, and vice versa. It's an actual geometrical model of what's going on. The Exposure Triangle seems to be an attempt to extend the balance scale picture to include ISO, and it's failed completely.

Or at any rate, I have not seen a single explanation that managed to get any further than "here's the exposure triangle. These three settings are interconnected. Let's look at some examples!"


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## SCraig (Aug 2, 2012)

amolitor said:


> Just as a for instance, suppose we forget ISO for the moment.


You can no more forget ISO than you can shutter speed or aperture.  There ARE three factors involved, not two.  Each with distinct advantages and disadvantages.


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## Buckster (Aug 2, 2012)

amolitor said:


> What is UP with this "exposure triangle" idiom? Every beginner's guide to photography web site seems to have picked this thing up, but it makes no sense to me. Don't get me wrong, I understand exposure just fine, thanks. It's the use of the triangle that's a mystery to me. At best it seems to capture the idea that "ISO, shutter speed, aperture are interconnected" which I can accomplish with the sentence "ISO, shutter speed, and aperture are interconnected" or with any number of graphical representations.
> 
> Is there something I am missing? If I, I dunno, imagine that the correct EV is a dot somewhere inside the triangle.. then when I adjust the shutter speed.. the dot.. I dunno, moves away from something and toward something else?
> 
> ...


I wouldn't stand for it, if I were you.  You should drop everything else and devote your life to destroying this terrible idea of the "exposure triangle".  It's truly _*that*_ important.


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## amolitor (Aug 2, 2012)

AAAAAA

I do understand exposure, people. Please stop assuming that I don't.


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## Phototripper (Aug 2, 2012)

For anyone that wants to practice exposure techniques, check out CameraSim (CameraSim | SLR Photography Demystified). This is a great way to experiment with various camera settings and see the results immediately.


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## manaheim (Aug 2, 2012)

That's it.  We need to ban the triangle!  Who's with me???



Actually I never knew what it was before now.  Sounds like a nice graphical way to demonstrate a concept.  People are naturally more visual creatures so it makes sense that this would be helpful to many folks.  If it isn't necessary for you then you're likely just well beyond needing it, so don't worry about it, move on... And remember it exists for when you need to explain it to someone more visually oriented than you.


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## Robin Usagani (Aug 2, 2012)

exposure triangle is basic though.  This is beyond basics section


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## KmH (Aug 2, 2012)

I have never liked the triangle analogy either, for a variety of reasons, and refer to it as the 'exposure adjustment triad'.

Each person able to come to grips with manually controlling a camera eventually develops their own mental model of how the 3 exposure values relate to one another.

Another evolution in that mental model has to take place when/if strobed light is added to the photographers bag-of-tricks.


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## RacePhoto (Aug 2, 2012)

SCraig said:


> amolitor said:
> 
> 
> > Just as a for instance, suppose we forget ISO for the moment.
> ...





Buckster said:


> I wouldn't stand for it, if I were you.   You should drop everything else and devote your life to destroying this  terrible idea of the "exposure triangle".  It's truly _*that*_ important.



That got me laughing, and I agree.

Or go analog, with film, it's what you loaded, so much simpler, you can't change on the fly. :thumbup:

It's really a simple concept change one and the others are altered. I can't believe there's some controversy or big forum conflict over basic physics?

Let me help:

1) Canon or Nikon?
2) RAW or JPG?
3) UV filter protection or not?
4) sRGB or RGB?
5) What makes someone a "professional" photographer?
6) Who is really "America's Team? Packers or Dallas 

I can't believe people are arguing about a simple concept used to teach how three factors interact to control Exposure!

It's all wrong anyway, it should be a 
	

	
	
		
		

		
			





 Reuleaux triangle.


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## tirediron (Aug 2, 2012)

*DOWN WITH TRIANGLES!!! 

and while we're on the topic, I'm not very fond of ovals either...*


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## Solarflare (Aug 2, 2012)

I honestly have no clue anymore what this thread is all about.

The exposure triangle is very simple and basic - raise one of the three parameters, then you have to lower one of the two other parameters by the same amount, or end up with an overexposed picture. And vice versa.

What is there to oppose ? Its like opposing the rule of proportion. You dont need to use it to compute, but you need to know what it represents.





RacePhoto said:


> go analog, with film, it's what you loaded, so much simpler, you can't change on the fly. :thumbup:


You cant change it on the fly on digital cameras either, it usually involves ugly menu surfing on really every digital camera I've checked out so far.


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## Buckster (Aug 2, 2012)

Solarflare said:


> RacePhoto said:
> 
> 
> > go analog, with film, it's what you loaded, so much simpler, you can't change on the fly. :thumbup:
> ...


LOL! You're so funny ...!!

1. Push ISO button next to shutter button.
2. Spin wheel to new ISO.

Most of us can do it without even taking our eye from the viewfinder of our DSLR.

As for changing ISO in the middle of a shoot with film, that's what film backs are for.


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## unpopular (Aug 2, 2012)

The "exposure triangle" teaches exposure compensation, but does not teach exposure control.

I think it was first illustrated by Bryan Peterson, so so what can you realistically expect?


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## amolitor (Aug 2, 2012)

RacePhoto:

"I can't believe people are arguing about a simple concept used to teach how three factors interact to control Exposure!"

My point is that the exposure triangle doesn't teach anything, and it most certainly does not teach _how the three factors interact_. It's one of those things that looks great once you've grasped the incredibly trivial details of this interaction, but it actually makes things worse before you understand these details. I suspect that the "exposure triangle" is a substantial factor in why newbies these days have trouble grasping exposure, which SHOULD take about 2 minutes to explain, an hour to understand fully, and a week to put in to practice. And yet, we see newbies struggling.

Everyone reading this should care about these pedagogical devices, since when they're bad and confusing, they generate cluenless newbies that clutter up forums like this one with their confusion over simple simple things. Do you enjoy reading these sad postings from newbies who "have been struggling with exposure and it's soooooo confusing" with their terrible overexposed pictures? I don't. I don't like the clutter, and I also want to help them as individuals AND as a group.

Kill The Exposure Triangle.


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## 480sparky (Aug 2, 2012)

Solarflare said:


> .............You cant change it on the fly on digital cameras either, it usually involves ugly menu surfing on really every digital camera I've checked out so far.



I just press the ISO button, then spin the rear command dial.

100 to 25,600 in .37 sec.


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## 480sparky (Aug 2, 2012)

amolitor said:


> .............Kill The Exposure Triangle.




And replace it with.......... _The Amolitor Method of Exposure Control_?

How's that go, again?


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## RacePhoto (Aug 2, 2012)

And this folks is what _"trolling"_ is all about. Catching a whole group of people in a forum, hook, line and sinker, into responding to some meaningless debate. 

:hail:  *amolitor you deserve an award for this one.

*


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## amolitor (Aug 2, 2012)

Well, sparky, I don't have a simple graphic that explains it, although I do have a slightly complicated one. It's pretty hard to compress 3 factors on to a 2 dimensional medium in any simple way. Maybe there's a good way to do it in this case, but I haven't come across it yet.

I generally just use words to explain exposure, they work pretty well, luckily.


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## unpopular (Aug 2, 2012)

... or the zone system

I just don't understand at all why people, ordinary people, not rocket scientists, were able to learn basic exposure control 10 years ago. We had AE then. We had multisegment metering. Yet, people could understand the concept of 1:1 ratios. I know. Those advanced civilizations of the past!


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## tirediron (Aug 2, 2012)

amolitor said:


> ...My point is that the exposure triangle doesn't teach anything, and it most certainly does not teach _how the three factors interact_...


No, and nor is it meant to; it's simply a graphical representation, which, in the Beginner's Photography courses that I have taught, the majority of my students have found very useful.  Your mileage may vary.


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## Ysarex (Aug 2, 2012)

amolitor said:


> Just as a for instance, suppose we forget ISO for the moment.
> 
> Imagine a graphic of a teeter-totter, a see-saw, or a balance scale. Label one side "shutter speed" and the other "aperture", and then write underneath it "keep the scale balanced to keep the exposure the same". Now we see clearly and unambiguously (assuming we have proper labels) that if we make the shutter speed faster, we must make the aperture wider, and vice versa. It's an actual geometrical model of what's going on. The Exposure Triangle seems to be an attempt to extend the balance scale picture to include ISO, and it's failed completely.
> 
> Or at any rate, I have not seen a single explanation that managed to get any further than "here's the exposure triangle. These three settings are interconnected. Let's look at some examples!"



You'd be surprised how much trouble some people have understanding exposure. I have struggled for years trying to figure out why this is so and to come up with effective instructional models.

I don't like the triangle model either. It was introduced with the advent of digital photo to deal with the new digital facility to alter ISO frame to frame. Before digital you put a roll of film in the camera and the ISO was immediately locked down. So you could then move on to your see-saw model, but that's also inadequate.

Both the see-saw and the triangle models fail to account for another variable -- fluctuating light intensity which is further complicated by variations in contrast, and subject reflectance properties. The models also fail to account for the behavior of the "magical meter" or the need for a measuring tool.

One of the problems with any of these models is that they fail to account for variations in function between the parameters as Solarflare was pointing out. The shutter speed and aperture both function like valves that permit you to control the "flow rate" of light as a valve would control water and yet the ISO has no corollary function. This may be part of why you're objecting to the triangle and it's one reason I don't like it. You place each variable on equal sides of a triangle but one of them has a uniquely different function -- confusion follows. At least the triangle needs to have the base (ISO) color coded or marked as different than the two sides (shutter/aperture). And then there needs to be a way to add in the variable of light intensity: Hey! I've got it! And this model has built-in incentive as well $$$$!








I have witnessed time and again adults learn to manipulate a camera's controls with moderate success (zero the meter by changing one or another of the triangle variables) but still not really understand what's going on. It's like music. I've met many accomplished musicians who can play an instrument and even read music and yet devolve into stammering idiots when asked why there are two missing black keys on the piano keyboard.

Joe


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## unpopular (Aug 2, 2012)

"Zero The Meter" is precisely the problem.


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## Steve5D (Aug 2, 2012)

amolitor said:


> Yes, yes, I get that it captures the idea that the three things are interconnected. My point is that it seems to capture nothing whatsoever ELSE.



Is it supposed to?

I see no reason for it to be complicated...


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## Helen B (Aug 2, 2012)

The triangle doesn't make much sense to me either. Too many questions about what means what. What about a simple circle, with the circumference divided into four arcs (brightness, sensitivity, time, aperture)? The circle must be complete, so changing the length of one arc requires a change in one or more of the other three? (If one really feels that a graphic is necessary)


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## amolitor (Aug 2, 2012)

I use a bucket analogy:

You want to fill a bucket with light. Aperture is hose size, shutter speed is how long to stand there filling, and ISO is how big the bucket is.

The meter tells you how to fill the bucket up halfway. If you want it less full, that's the same thing as darker. If you want it more full, that's lighter.

Aperture is dumb and goes backwards, smaller numbers mean a bigger hose.

DONE.

Words. They work.


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## Buckster (Aug 2, 2012)

amolitor said:


> Aperture is dumb and goes backwards, smaller numbers mean a bigger hose.


No, they don't.  They're fractions.


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## amolitor (Aug 2, 2012)

Oh, smaller numbers don't mean a bigger hose? So f/2.8 lets in LESS light then f/5.6? Shoot, this is all new stuff. Let me take notes.

All the stuff between the colon and the word "DONE" is my explanation targeted at newbies, just FYI. Again, for those of you not keeping up: I understand exposure just fine, thanks.


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## MTVision (Aug 2, 2012)

Solarflare said:
			
		

> I honestly have no clue anymore what this thread is all about.
> 
> The exposure triangle is very simple and basic - raise one of the three parameters, then you have to lower one of the two other parameters by the same amount, or end up with an overexposed picture. And vice versa.
> 
> ...



You don't have to menu surf with the d5100 either. You can assign ISO to the Fn button then hold that button and spin the wheel....


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## unpopular (Aug 2, 2012)

I agree with Helen. The Exposure triangle does not account for the very thing it is intended to illustrate: exposure. Where does the subject come into the picture? Would a lighter or darker than middle grey subject change the shape of the triangle?


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## unpopular (Aug 2, 2012)

MTVision said:


> You don't have to menu surf with the d5100 either. You can assign ISO to the Fn button then hold that button and spin the wheel....



You don't even have to with the very menu-centric a350!


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## manaheim (Aug 2, 2012)

amolitor said:


> I use a bucket analogy:
> 
> You want to fill a bucket with light. Aperture is hose size, shutter speed is how long to stand there filling, and ISO is how big the bucket is.
> 
> ...



I agree with all of what you're saying except the last part.  Words kinda _don't _work... at least not without other supporting elements.

Look at what you just did... you created a word PICTURE with your bucket analogy.

As I mentioned, people are very visual.  What you've done is created something people can visualize.  If words really worked, then you would say...

"Aperture is the hole that allows light to transfer through the lens to the camera.  ISO is the sensitivity of the sensor/film to that light.  Shutter time is the length of time you allow the shutter to remain open and expose the light to the sensor or film.  The higher the ISO, the more sensitive, therefore the less light it needs to expose the image.  The wider the aperture, the more light goes to the sensor, the less time it needs to expose the image.  All of these things are inter-related, so one affects the other."

Clearly if you said THAT to someone new to this they would look at you like you just offered them a lightly grilled squirrel.  Whereas your WORD PICTURE forms a nice mental illustration.

The triangle is evidently another form of illustration- though one that appears to be less useful to some folks- so perhaps yours is better, which is cool.  I certainly like your word picture very much and plan to use (steal) it.  There may be better ones.  But everyone thinks differently, so for some the triangle might make more sense than your bucket analogy.


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## amolitor (Aug 2, 2012)

You (everyone who likes) should, of course, feel free to use my word (picture) as you see fit. I think it's pretty decent myself!


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## unpopular (Aug 2, 2012)

I am almost 100% certain you did not invent that analogy...


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## amolitor (Aug 2, 2012)

It has to have been invented by many people all over, especially since it is only very very slightly an analogy. A sensor damn near *is* a collection of buckets for collecting light in. ISO *is* the size of the bucket, shutter speed and aperture are pretty much exactly the same thing as a hose of variable diameter and duration, except for light instead of water.

If I didn't steal it wholesale, I probably stole all the parts. It's been, uh, 30 years, so I've collected a lot of mental detritus on the subject. All our ideas are products of the stuff we've picked up along the way, eh?


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## Ysarex (Aug 2, 2012)

unpopular said:


> I am almost 100% certain you did not invent that analogy...




I've been using it for at least 30 years. In mine we're in the lab at the darkroom sink. The aperture is the valve in the faucet which can be adjusted. Different size graduates are different ISO values, etc. I'd stand there with a group of new Photo I students and actually run the water.

Joe

Edit: "they would look at me like I just offered them a lightly grilled squirrel."


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## unpopular (Aug 2, 2012)

amolitor said:


> ISO *is* the size of the bucket



WHOA! You mean changing ISO changes the physical characteristics of the sensor element?

I did not realize that! Here I thought it simply increased analog amplification...

No. This is not accurate even with film.


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## amolitor (Aug 2, 2012)

Film technology resembles buckets for collecting light in.. basically no way whatsoever.

Changing the ISO of the sensor does not change the physical characteristics of the bucket that is collection light, it does change the effective electrical characteristics, to the point that the bucket "becomes full" sooner. You may choose to view this as "the bucket does not changes size, but we're putting bigger photons in it" or whatever else you like. I happen to think that a bucket which fills up faster is usefully considered as "smaller".

EDIT: why are you picking at miniscule trivialities like this? "you didn't invent it" and "the buckets don't REALLY get smaller" are you in sixth grade or something?


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## Jaemie (Aug 2, 2012)

Exposure Wiener Dogs.

There. I've solved the matter.



Wiener dog #1 is named Mei-Ling. She controls shutter speed. Poke her gently and she bites the tail of...

Wiener dog #2, named Isolde. She used to control ASA, but now just works with ISO. Petting her soft black coat causes her to nudge...

Wiener dog #3, whose name is Effie. Of course, Effie manages f-stop. But you knew that already.

Sometimes these three adorable hot dogs play in other ways (e.g., Isolde with Effie, or Mei-Ling by herself), but they always know what the other is doing, such is their mutual love and affection.


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## unpopular (Aug 2, 2012)

amolitor said:


> EDIT: why are you picking at miniscule trivialities like this? "you didn't invent it" and "the buckets don't REALLY get smaller" are you in sixth grade or something?



Bad mood. Sorry.


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## manaheim (Aug 2, 2012)

amolitor said:
			
		

> You (everyone who likes) should, of course, feel free to use my word (picture) as you see fit. I think it's pretty decent myself!



You sorta skipped over my other point though...

You know, I'm starting to notice a certain behavior pattern around a few more recent members here.

Anyone else seeing this?


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## manaheim (Aug 2, 2012)

Jaemie said:
			
		

> Exposure Wiener Dogs.
> 
> There. I've solved the matter.
> 
> ...



My name is manaheim and I support this method.


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## 480sparky (Aug 2, 2012)




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## tirediron (Aug 2, 2012)

Jaemie said:


> Exposure Wiener Dogs.
> 
> There. I've solved the matter.
> 
> ...



If you're going to have Isolde, than you have to change Effie's name to Tristan!!!!


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## SCraig (Aug 2, 2012)

Ysarex said:


> ... It was introduced with the advent of digital photo to deal with the new digital facility to alter ISO frame to frame. ...


No, it wasn't.  I first read about it back in the 1960's, long before digital photography became commonplace.  It was just as pertinent then with film as it is today with digital exposures.


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## amolitor (Aug 2, 2012)

unpopular said:


> amolitor said:
> 
> 
> > Bad mood. Sorry.
> ...


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## amolitor (Aug 2, 2012)

manaheim said:


> You sorta skipped over my other point though...



You are free to assume that if I didn't respond to it, I either agree with it, or don't feel that my disagreement with it is worth discussing. I thought I implicitly acknowledged your point when I referred to my bucket description as a "word (picture)", in any case.


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## Derrel (Aug 2, 2012)

amolitor asked, "_What is UP with this "exposure triangle" idiom? Every beginner's guide to photography web site seems to have picked this thing up, but it makes no sense to me. Don't get me wrong, I understand exposure just fine, thanks. It's the use of the triangle that's a mystery to me. At best it seems to capture the idea that "ISO, shutter speed, aperture are interconnected" which I can accomplish with the sentence "ISO, shutter speed, and aperture are interconnected" or with any number of graphical representations._"

Yes, I agree with your thoughts on this subject. I have been "into photography" since around 1973. I studied it in junior high school, high school, and university and later community college classes, as well as having read several hundred photography books covering many sub-types of photography. I can not recall ever ONCE hearing the term "exposure triangle" in literally decades. MY first recollection was that I first heard about it* here on TPF *a few years back. I think it was designed as a shorthand way to help newbies come to grips with how to set up their new-fangled digital cameras. Older texts always assumed that film speed was "a given"...the idea that the exposure triangle is an old concept that goes back to the film days is, I think, erroneous. In older texts, again, the FILM SPEED, stated in ASA, or DIN most often was considered "a given". 

The idea that the sensitivity value (ASA/DIN/the later ISO) of the capture medium could be changed on a *shot-to-shot-to-shot basis* is something that ONLY became common once digital became good, and prevalent. We used to have to use sheet film, or a MF rollfilm system with interchangeable backs if we wanted to adjust exposure via ASA/DIN/ISO sensitivity. Either that, or PAY EXTRA for push- or pull processing! Older discussions about exposure did NOT encompass the idea that "exposure" was a "triangle"---that idea,and that specific phrase,*exposure triangle* is in my opinion, a digital-era paradigm shift that has become part and parcel of digital photography; the exposure triangle idiom is something "new" in the world of photographic terminology and conceptualization of photo methods/principles.

"Exposure triangle" is, uh, kind of like the *hip-hop* music that Gershwin used to write, ya' know...


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## manaheim (Aug 2, 2012)

amolitor said:


> manaheim said:
> 
> 
> > You sorta skipped over my other point though...
> ...



Ah.  No, that wasn't clear.  Sorry.   Lots of qurkiness around here lately.  I'm starting to think there are boogeymen in every closet.


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## Buckster (Aug 2, 2012)

amolitor said:


> Oh, smaller numbers don't mean a bigger hose?


Correct.



amolitor said:


> So f/2.8 lets in LESS light then f/5.6?


No, the smaller number, f/5.6, lets in less light than the larger number, f/2.8. 



amolitor said:


> Shoot, this is all new stuff. Let me take notes.


Good idea.  Write this one down:

f/5.6 is smaller than f/2.8, just as 1/5 is smaller than 1/2.


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## amolitor (Aug 2, 2012)

Sure, Buckster. Everyone thinks of the numerical designations for apertures as the denominator of a fraction, ESPECIALLY newbies. Denominators, for reference, are dumb and go backwards. Bigger numbers mean smaller fractions, as you so wisely point out. Thanks for backing me up.


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## o hey tyler (Aug 2, 2012)

amolitor said:


> I use a bucket analogy:
> 
> You want to fill a bucket with light. Aperture is hose size, shutter speed is how long to stand there filling, and ISO is how big the bucket is.
> 
> ...



This is the worst and most convoluted analogy I've ever heard regarding exposure.


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## o hey tyler (Aug 2, 2012)

amolitor said:


> Sure, Buckster. Everyone thinks of the numerical designations for apertures as the denominator of a fraction, ESPECIALLY newbies.



 Well, the faster that one understands that, the faster one understands that a larger f/stop is technically a larger number. Leads to less confusion in the long run.


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## timor (Aug 2, 2012)

amolitor said:


> AAAAAA
> 
> I do understand exposure, people. Please stop assuming that I don't.


I like your declaration or self description on your blog.
Just to add some confusion: in film photography term "perfect exposure" does not exist. There is only an approximation of an exposure.


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## BRN1 (Aug 2, 2012)

I like dogs. Hot dogs and corn dogs too.


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## table1349 (Aug 2, 2012)

This thread is the biggest waste of bandwidth in quite some time around here.


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## Derrel (Aug 2, 2012)

gryphonslair99 said:


> This thread is the biggest waste of bandwidth in quite some time around here.



No...no way...there are several other current threads that are equally, or *even MORE-worthless* than this one. Give some of the other posters here some credit! lol


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## Fred Berg (Aug 3, 2012)

amolitor said:


> I use a bucket analogy:
> 
> You want to fill a bucket with light. Aperture is hose size, shutter speed is how long to stand there filling, and ISO is how big the bucket is.
> 
> ...



Hedgecoe used a very similar analogy to explain the relationship between aperture and shutter speed. His beaker/bucket didn't change size to account for the DIN value, though. I like your model and also the idea of the see-saw/weighing scales. If the fulcrum is shown as DIN, it could be very useful to demonstrate/explain the relationship between this, aperture and shutter speed, I think.

I agree that the exposure triangle is confusing, especially for people new to photography.


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## bratkinson (Aug 4, 2012)

Having always been mathematically inclined, I "picture" (pun intended) the exposure triangle as a mathematical formula something like:

*A x B x C = P*

Unfortunately, P is an 'indefinite' or non-specific number that I think of as &#8216;the *P*erfect *P*icture&#8217;, and depends on the eye of the beholder.

Let me explain:
If A x B x C = 1000 (a constant value), then it&#8217;s easy to see that as A increases, then B and/or C must decrease to compensate to get the result of 1000. Likewise, decreasing B, for example, would require an increase in A and/or C. Unfortunately, the exposure triangle not this &#8216;simplistic&#8217; of a math formula, and there&#8217;s intended and sometimes unintended consequences to altering any of the values.

Let&#8217;s say A = f-stop value. If a larger f-stop (aperture) is used (numerically smaller value), then, increasing f-stop increases the exposure and therefore shutter speed and/or ISO must be lowered to get the same result. Similarly, if B = Shutter Speed, increasing the shutter-open time (1/x th second, where x is numerically smaller) requires that ISO be decreased and/or aperture must be decreased as well to get the same result. 

So, for you mathematicians out there, the formula would actually be something like:
*
(100 - f/stop) x (1000 - shutter speed expressed without the fraction) x ISO speed = P *

Note: I chose 100 as a max f-stop value as I don&#8217;t know if f/100 is possible (pinhole, perhaps?). Similarly, I chose 1/1000[SUP]th[/SUP] second as a &#8216;max&#8217; shutter speed, but in reality it is probably more like 32,000 or something equally as large. 1000 used here for simplicity sake. 

The 100 - f/stop calculation is there to give a larger number from smaller f-stop numbers. f 22, for example, would result in a value of 88, and so on. Shooting at f 4 (96 value in the calc) instead of f 22 will result in more light hitting the sensor if nothing else is changed.

Similarly, 1000 - shutter speed is used to give a smaller number the faster the shutter speed (eg, 1/100 sec speed would use only the 100 number in the calculation, giving a result of 900). Longer shutter open times result in larger numbers in this calculation. Decreasing shutter open time (eg, 1/30[SUP]th[/SUP] to 1/100[SUP]th[/SUP]) would therefore result in a smaller number in this calculation, lowering the total exposure value &#8220;P&#8221;.

Lastly, increasing ISO speed would necessitate a reducing one of the other numerical values in my equation, but in actuality, you'd be increasing the shutter speed (less time open) or going to a smaller f-stop like f 16 or f 22 to still get a good exposure.

Before everybody&#8217;s head starts spinning, know that I don&#8217;t do *any* of these &#8216;complex&#8217; calculations in my head when I go to take a picture. I&#8217;m too old for that kind of stuff. Instead, I simply think of it in the simplistic A x B x C = P. Changing any of the three will require compensating (opposite) changes in either or both of the other two to get the same result. I&#8217;m not really saying &#8216;A = f/stop, etc.&#8217; It&#8217;s simply A x B x C, without assigning meanings or values of any kind to them.

As mentioned at the top, there&#8217;s additional, intended and non-intended consequences when changing ANY of the values. 

On the intended side, simply increasing the aperture size and changing nothing else will result in a &#8216;brighter&#8217; picture, due to more light hitting the sensor. But there&#8217;s a limit to how bright is &#8216;right&#8217;. If the picture gets too bright, the highlights wash out. And at the other extreme of under exposure, what&#8217;s in the darker areas have no visible details recorded.

Increasing aperture size also DECREASES the depth of field, that portion of the picture where everything is in focus. At f 32 (smallest aperture), almost everything will be in focus (depth of field) that&#8217;s farther away from the lens than its closest focal distance. At f1.2, the depth of field is frequently measured in inches, even fractions of an inch for some lenses. Note that narrower depth of field is desirable in some shooting situations to &#8216;bring out&#8217; the subject of the photo, while making everything else a little or a lot fuzzy, also known as bokeh. Some lenses produce better bokeh than others, depending on their construction and quality (and price). Of course, increasing aperture size requires decreasing either/or shutter open time or ISO.

Making shutter speed adjustments either increases or decreases the total amount of light hitting the sensor. Shutter speed variations are good for making long (often, minutes!) night exposures when the camera is on a tripod. But in most situations, long shutter open times are more like ¼ or 1/10 or 1/30 of a second. The long open time lets in more light, and is useful in situations where nothing is moving. People shots are almost always blurred at these speeds, even if they are sitting down and smiling. Yours (and mine, too) hands will move slightly with every heartbeat as well, and at 1/30[SUP]th[/SUP], there could be a blur. Speeding things up to 1/60[SUP]th[/SUP] can stop &#8216;slower&#8217; human movement (like holding a pose), but for most people pictures, 1/100[SUP]th[/SUP] or faster is required to stop them for sure. Indianapolis race cars, on the other hand, need shutter times of 1/500[SUP]th[/SUP] second or even faster to &#8216;freeze&#8217; them in the picture. So, by increasing shutter open time, more light hits the sensor. But subject movement can end up in a blur if too slow. Too fast, and the pictures get dark, unless compensating increases are made to aperature and/or ISO. Shutter speed synchronization with flash units is a lengthy subject in itself, has various added effects, and not a part of this epistle.

ISO is probably the easiest to understand. Think of a bird pecking at seeds on the ground. Some birds peck seeds faster than others. Of course, me armed with a Shop-Vac can clear the ground of all the seeds in a heartbeat or three. ISO is the same. Lower ISO settings are like birds pecking away to gather the necessary light to make the picture. With a Shop-Vac (high ISO setting), all the light is gathered in less than a heartbeat. The problem with using a Shop-Vac in the above example is it also picks up a lot of dirt with the seeds. This is comparable to noise, ie, odd, multi-colored pixels in the resultant picture, mostly visible in darker areas. Slower ISO speeds closer to 100 or 200 rather than 3200 reduces the &#8216;dirty&#8217; noise in the pictures. How high is &#8216;high ISO&#8217;? It varies from camera maker to camera maker, and even from camera model to model, as well. Generally, the newer the camera, the better the handling of faster ISO speeds&#8230;How big is YOUR Shop-Vac?

Of course, there&#8217;s even more to the &#8216;exposure triangle&#8217; adjustment consequences than discussed above, like color density, edge focusing, and other generally pro-level issues. But for me, and for most non-professional photographers, I suspect, the simple A x B x C = P and the consequences described above is more than enough to keep our heads spinning!


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## unpopular (Aug 4, 2012)

That explanation is on an order of magnitude more complicated than it needed to be.


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## Tee (Aug 5, 2012)

amolitor said:


> You (everyone who likes) should, of course, feel free to use my word (picture) as you see fit. I think it's pretty decent myself!



I think Byran Peterson did in his "Understanding" volumes.  Like almost word for word.


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## Ballistics (Aug 7, 2012)

amolitor said:


> Sure, Buckster. Everyone thinks of the numerical designations for apertures as the denominator of a fraction, ESPECIALLY newbies. Denominators, for reference, are dumb and go backwards. Bigger numbers mean smaller fractions, as you so wisely point out. Thanks for backing me up.



Wow. Haha. This has to be one of the greatest things I have heard someone say on here in a long time. 

Denominators are dumb lmfao! 

They don't go backwards.
Do you really need to have fractions explained to you?

Newbies don't think like that? Is everyone new to photography in 1st grade?


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## unpopular (Aug 7, 2012)

f-stops are counter-intuitive. It's hard to say a translation of f/5.6  to f/4 is half of anything. Sure, it makes optical sense, but people are not used to dealing with exponential fractions on a daily basis. Still, hardly anything people can't overcome.


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## Fred Berg (Aug 7, 2012)

I think most people normally think of 22 as bigger than 2. Understanding how to handle aperture settings is a bit like learning to steer a boat.


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## JAC526 (Aug 7, 2012)

Ballistics said:


> amolitor said:
> 
> 
> > Sure, Buckster. Everyone thinks of the numerical designations for apertures as the denominator of a fraction, ESPECIALLY newbies. Denominators, for reference, are dumb and go backwards. Bigger numbers mean smaller fractions, as you so wisely point out. Thanks for backing me up.
> ...



You give people too much credit.


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## Solarflare (Aug 7, 2012)

timor said:


> Just to add some confusion: in film photography term "perfect exposure" does not exist. There is only an approximation of an exposure.


 Why, thanks for adding more confusion. :mrgreen:

Why does perfect exposure not exist ? Its when the brightest pixel is almost at its maximum. I would have thought thats a quite well defined state.





Ballistics said:


> amolitor said:
> 
> 
> > Sure, Buckster. Everyone thinks of the numerical designations for apertures as the denominator of a fraction, ESPECIALLY newbies. Denominators, for reference, are dumb and go backwards. Bigger numbers mean smaller fractions, as you so wisely point out. Thanks for backing me up.
> ...


Um.

ISO is 100, 200, 400, 800, 1600, ... (and sometimes ISO 50)

Aperture is f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, ...

Shutter Speed is 1/15 sec, 1/30 sec, 1/60 sec, 1/125 sec, 1/250 sec, 1/500 sec, 1/1000 sec, ... (and of course also 1/8, 1/4, 1/2, 1, 2, 4, 8, 15, 30 sec and Bulb mode)

Why is it not obvious that these numbers may look very confusing to a newbie ?


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## KenC (Aug 7, 2012)

Solarflare said:


> Why does perfect exposure not exist ? Its when the brightest pixel is almost at its maximum. I would have thought thats a quite well defined state.



There are many creative images with quite a bit of pure white in them and also many with nothing even close to white.


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## Ballistics (Aug 7, 2012)

Solarflare said:


> timor said:
> 
> 
> > Just to add some confusion: in film photography term "perfect exposure" does not exist. There is only an approximation of an exposure.
> ...



I just hope, just one day, someone stops reading *into* my posts and just reads the words.
Go back and re-read my post, and show me how any of this was even the point I argued.


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## Ballistics (Aug 7, 2012)

JAC526 said:


> Ballistics said:
> 
> 
> > amolitor said:
> ...



No I don't, I just know that there are people who are able to understand how a fraction works before they pick up a camera. Like I did.


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## Seefutlung (Aug 7, 2012)

Buckster said:


> amolitor said:
> 
> 
> > Oh, smaller numbers don't mean a bigger hose?
> ...



Aperture = ratio 

as in 1:5.6, 1:2.8, 1:11

Gary


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## laurenvictoria (Aug 7, 2012)

Im still a beginner, and when I'm trying to understand exposure and such, that triangle ALWAYS shows up! and honestly i've stared at it for so long and never understand it. I guess its just a tool that really doesnt click with me.


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## Seefutlung (Aug 7, 2012)

laurenvictoria said:


> Im still a beginner, and when I'm trying to understand exposure and such, that triangle ALWAYS shows up! and honestly i've stared at it for so long and never understand it. I guess its just a tool that really doesnt click with me.



The triangle is just a reminder that there are three principal components to exposure and each component is connected to the other.

Gary


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## laurenvictoria (Aug 7, 2012)

Seefutlung said:


> laurenvictoria said:
> 
> 
> > Im still a beginner, and when I'm trying to understand exposure and such, that triangle ALWAYS shows up! and honestly i've stared at it for so long and never understand it. I guess its just a tool that really doesnt click with me.
> ...



oh wow thanks! I always thought there was so much more too it


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## Ballistics (Aug 7, 2012)

Seefutlung said:


> Buckster said:
> 
> 
> > amolitor said:
> ...



Ratio = Fraction


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## Helen B (Aug 7, 2012)

I think I'm beginning to understand this. You are saying that small apertures let in less light than larger apertures, but that small f-numbers let in more light than larger f-numbers.


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## unpopular (Aug 7, 2012)

Well, you see Helen, f/22 is actually a smaller number than f/1.8, that's because they are ratios not integers, and f/22 doesn't let in 1/22 the light that f/1 does, but rather much, much less light because of the logarithmic scale which they represent. Here at TPF we like to over complicate matters unnecessarily, so your simple, concise, clear and accurate explanations reached from education an years of actual experience is not welcome around here.


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## unpopular (Aug 7, 2012)

Seefutlung said:


> Buckster said:
> 
> 
> > amolitor said:
> ...



This is not accurate. It shoudl be as in f/5.6, 5/2.8, f/11 where f=focal length. Thus, a 50mm lens at f/5.6 has an entrance [iirc] opening of about 8.9mm (50/5.6=8.9). This is why we have f-stops, that way the diameter of the aperture is relative to the exposure value, not the focal length.


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## table1349 (Aug 7, 2012)

Helen B said:


> I think I'm beginning to understand this. You are saying that small apertures let in less light than larger apertures, but that small f-numbers let in more light than larger f-numbers.



As Clairee Belcher said in Steele Magnolias.... "Spoken like a true smart a$$." :thumbup:


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## table1349 (Aug 7, 2012)

laurenvictoria said:


> Seefutlung said:
> 
> 
> > laurenvictoria said:
> ...



Thank you for proving my opinion as to what a waste of band width this whole discussion has been, with the exception of your understanding now of what the "photo triangle" is.


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