The Exposure Triangle Is Misleading And Unnecessary.

I took a look at Langford to see if that phrase was in common use in the 70s and found no support there. Then I got distracted about whether the concept was common but not the ET phrase. And what I found was a load of complicating stuff about all the factors affecting exposure but what I interpreted as a clear statement that shutter speed, aperture and film speed were the 3 key things that the calculators on light meters needed to know to suggest appropriate settings.

Then I did a search for "exposure triangle" and was shocked to discover rather than being some kind of obscure, forgettable beginners introduction to film photography metaphor from 1848 as I had supposed, it is now seen as some kind of canonical statement and quoted, requoted and pushed everywhere on photography sites.

I need my own lawyer to translate my word choice into the standard nomenclature. It's so difficult to use the right words, near synonyms seem good enough when dashing off a post!

More like 2008 than 1848. The thrice-accursed triangle is really very recent, at least in photography.

Ascribing mystical properties to triangles probably goes back to the Pythagoreans, or earlier.

Don

Right. The ASA film speed standard that eventually became ISO was designed so that people couldn't play games with development times to make it look like their film was faster.

What the phrase ET means is important to standardise if this debate has any hope. I take ET to mean that shutter speed, aperture and film speed affect the overall density of your negative. And this means, you can arrive at a desired negative density by changing any of the three. Or you can maintain a desired density when you change one of them by changing one of the others in the opposite direction. This appears to be how it works with film. Which has always given me a sense that it was correct and that explains why it is used everywhere. However, given that ISO on a digital camera is not the same as film speed, the usefulness of ET is now questionable. At least that is what I thought this discussion was about. But re-reading posts is giving me a feeling that some people didn't think ET is correct for film either.

As far as Langford is concerned, he said nothing about ET as a phrase and his list of parameters affecting appropriate exposure settings is complicated. However, he does appear to confirm that as far as the exposure meter is concerned, shutter speed, aperture and film speed are the only inputs to the calculator (aside from the light level measurement) which implies to me that Langford supported the ET concept.

Plus one to that!

I have been know to rail against the ET myself, once or twice elsewhere.

It goes with the common statement that increasing ISO increases the sensitivity of the sensor (puke emoticon}

I wasn't referring to film at all when I said "'intensifying' raw". In normal circumstances very little can be done to a film latent image.
Grain and noise are different things, they even look differently.
Film doesn't have forced clipping of highlights when pushed. "Intensifying raw" forcefully clips highlights.
If anything, "intensifying raw" in analogue, pre-ADC, domain causes better shadows.
Yes, differences among cameras suggest different, camera-tailored strategies, especially if shooting raw. Not all cameras are different, however.

The word "exposure" in bothersome because it has different meanings in different contexts. In this thread some people define it explicitly as amount of light x time or some such formula. But many people use it more casually eg if an image is a bit dark on the screen, we'll "boost the exposure". I think a lot of confusion around meaning comes from people using the word in different ways and in different contexts. The somewhat overformal insistence on the correct use of terminolgy which can come across as pedantry is very important sometimes. I'm guilty of being too casual in the rush to get the words out the door. Most utterings benefit from a bit of time spend on revisions!

It looks like posts have an id in the url. Can you point me to the relevant post, ta.

Hi Ted

What I've learned is that changing ISO doesn't do any one thing. It depends. Which is mildly depressing because it makes working cameras more complex.

Thanks, I'll re-read.

p.s. my last couple of replies seem to have lost some of my text.

1. That aperture, shutter speed and ISO are co-equal independent variables that together make up 'exposure';

Is this not a particular use of the word "exposure"? In my mind "exposure", as you use it here, refers to the total incoming light received by the sensor - which is determined by the brightness of the light and how long it is received i.e. the brightness of the subject as seen by the camera, the aperture used to restrict this and the time the shutter is open. But a lot of people might think of the exposure as being the end result ie how dark or light the picture ends up being. As in "this exposure is too dark, you need to use a wider aperture". In this latter case, this is also affected by how sensitive the sensor is, its "film speed" as you could replace "use a wider aperture" with "increase ISO". With this usage the exposure triangle concept seem legitimate.

2. When coupled with the idea that "exposure" is an amount of light - that ISO, like aperture and shutter speed governs an amount of light;
What is exposure if it not an amount of light?

3. That is affects the amount of light by 'gain' - that is, the untutored beginner assumes - is that it creates more light, or -
4. That it makes the sensor 'more sensitive' so that somehow it sucks in more light (?);

Don't understand what is meant by 3 and 4 - can you clarify

5. That the penalty for more sensitivity is that the 'amplification' causes noise.
Hardly surprising people think this - it is pretty much what every camera review says. Noise increases with rising ISO. I'm guessing that what you object to is the idea that the increased noise is the result of increased amplification rather the image being more underexposed and it is underexposure rather than amplification that causes the extra noise?

6. As an alternate branch from 1, given that there is a 'correct exposure', that a certain amount of 'exposure' is 'needed' to make it correct, and back to 3.
I'm not sure what you are saying with this one. The way I think about "correct exposure" is that it is something that makes the picture look like you intended ie there is nothing wrong with a dark picture or a high key picture if that is how you want it to look. But I guess most people would think correct exposure is when you have good shadow detail, good highlight detail without clipping and the mid-tones are balanced to give a realistic looking bright image. How is this related to ET?