Exposure triangle explanation please.

Started Jul 9, 2013 | Questions thread
Limburger Veteran Member • Posts: 7,839
Re: Great Job Texinwien but,

texinwien wrote:

Guidenet wrote:

Tex, good morning.

I think most of us truly understand what ISO is today.

I'm not so sure about that. In practically every discussion of ISO that I see, a number of people who are obviously confused about ISO generally pop in and make their confusion well-known.

You've done a good job of clearing up some questions I had. I understand it better because of your excellent explanations.

Excellent - I'm glad you found my explanations enlightening.

On the other hand, ISO is a handy way of discussing brightness with regards to adjusting gain up front. In fact, when I'm adjusting it up front, I'm really not.

Only if you're shooting RAW.

I'm still after the fact, I suppose, but the information is stored in the RAW file and had an effect on the viewed image. It gives me an idea as to the default RAW view maybe helping me to guess as to how far I can push it after the fact.

I'm not saying you should be kept from setting a target gain up front, but you shouldn't be forced to do so, it should be possible to change that target gain after the fact, and novices shouldn't be required to factor it into their thinking when preparing to capture an exposure.

Give them two variables to think about (shutter speed and aperture) rather than forcing the third one on them, as well.

Also, as Jeff says, what's wrong with using the existing ISO model to describe this effect regardless on when it takes place? It seems to me the only confusing part is introduced when you wish to change the model and how it describes it.

What's right with it, especially if it causes so much confusion?

I think there is no need to change the current model application except to benefit prominents of smaller, more noisy sensors.

I'm sorry, what? How would the changes I describe be to the benefit of smaller, more noisy sensors? Please explain

By only being able to describe a sensor's ability to take gain in post and by considering it to be strictly a post applied process, we not only change the way we describe the process, but we alter a way to easily measure the ability of a sensor to output data that can accept increased gain without noise.

This is theoretically and practically incorrect, and shows that you haven't yet understood today's lesson about ISO, unfortunately.

I note the demand every year or so to lose the ISO description is often led or spearheaded by 4/3rd owners and other crop sensor proponents. Not always, because there are often a lot of wannabes willing to jump on any bandwagon in order to look clever (Please believe and I promise I'm not describing you). After a month, this phenomena seems to dissipate and we continue on with our typical description of gain as ISO. People who own cameras that handle noise better seem to have no issue with the current ISO usage.

Well, you're wrong on this front. I know several full-frame camera shooters who have the same complaints about ISO that I have.

Again, please be specific about how such a change would benefit crop-sensor cameras more than it would benefit full frame (or medium format or any other format) cameras.

With a small sensor you hit the wall quicker and would reveal the benefit what you try to point out quicker.

I'll save you some time and tell you it won't, in any way. Feel free to make your case if you continue to disagree.

So is there an alternate motive? Probably only subconsciously. One would naturally support something which has recognizable benefits to them. People who don't see an issue, would not.

Again, what recognizable benefits would the owner of a crop sensor camera get that the owner of a D3S wouldn't? The answer is still 'none'. Feel free to offer concrete examples if you disagree.

As a user of mostly three full fame cameras, including a Nikon D3S, I see no issue with the current method of describing gain.

I know another D3S user whose knowledge of the physics behind photography far outstrips mind, and he makes the same case against ISO that I do. The ISO model offers no benefits to full frame shooters that it doesn't offer to crop sensor shooters. Switching to something more logical would offer no benefits to crop sensor shooters that it wouldn't offer to full frame shooters, either.

You're just wrong on that count.

So, for most people, I don't see any reason to change how we describe an effect which looks and acts the same for both sides.

You're an excellent example for why ISO should be done away with and replaced with something more intuitive. It's quite obvious that you have a very tentative understanding of ISO. It's obviously a confusing topic to you, based on your words in this post. If the topic is confusing to someone like you, who obviously has a lot of experience with photography, well, I can't think of a better proof that we need to replace it with something more intuitive.

And going to your final image, on screen or print would anybody notice?

The final medium I think should be thrown in as well.

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Cheers Mike

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