Beginner Iso not part of exposure triangle AP

Terrywoodenpic said:
However when ever you move the line away from the native sensitivity of the sensor there are consequences.
especially in terms of Noise levels and the Tonal range it is possible to capture.

An ISO invariant sensor is one where you can can move the line with in reason, and with out undue quality problems.
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I don't think that is what ISO invariant means; it means you can "move the line" in post without any *greater* penalty than you would incur doing it during capture... you still pay the penalties.
 
sk66 said:
I don't think that is what ISO invariant means; it means you can "move the line" in post without any *greater* penalty than you would incur doing it during capture... you still pay the penalties.
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Yes, but ISO-invariance isn't quite the same as bumping the brightness post-capture. It's better than that, with a real benefit.

It's like ETTR (Expose To The Right, of the histogram) in that it allows you to pull more out of the shadows, but with ETTR this usually means you've got to lose some highlights (hopefully unimportant ones) because they will inevitably blow. With an ISO-less or ISO-invariant sensor, you can adjust exposure to retain those highlights, but still pull an extraordinary amount of detail from the shadows in post.

Edit: there's more. With ETTR, what happens in practise is that you usually have to use a longer shutter speed, with the drawbacks that go with it. No need to do that with an ISO-invariant sensor.

Sorry, this is getting a bit techy ;) I guess that when comparing the two - ETTR vs ISO-less sensors, in theory the ETTR version would have less noise in the shadows because it's received less light/photons. I've not done that comparison, but I'd put money on there being nothing in it if only because ISIO-less sensors are so bluddy good for shadow detail. ISO-invariance is the main reason why I've not upgraded to a Canon 5D Mk4 yet - it's pretty good, but not as good as some Nikons and Sonys.
 
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HoppyUK said:
It's like ETTR (Expose To The Right, of the histogram) in that it allows you to pull more out of the shadows, but with ETTR this usually means you've got to lose some highlights (hopefully unimportant ones) because they will inevitably blow. With an ISO-less or ISO-invariant sensor, you can adjust exposure to retail those highlights, but still pull an extraordinary amount of detail from the shadows in post.
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That's just a difference between a global adjustment and a selective adjustment; not really a characteristic of being ISO invariant. But I suppose it's a valid point given that the camera can't do a selective adjustment to a raw file.

And that goes to the original post where the author stated "Raw files don't have any inherent ISO rating of their own." IMO that is erroneous because amplification (analog/digital ISO) changes the data written into the raw file, it is not just an exif header entry like W/B and the rest are. If you make a global adjustment w/ ISO that causes areas to clip white/black in the raw file they will not be recoverable in post.
 
sk66 said:
I don't think that is what ISO invariant means; it means you can "move the line" in post without any *greater* penalty than you would incur doing it during capture... you still pay the penalties.
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That is why I said within reason and with out undue quality problems, these things all limit the range of the invariance.
 
sk66 said:
That's just a difference between a global adjustment and a selective adjustment; not really a characteristic of being ISO invariant. But I suppose it's a valid point given that the camera can't do a selective adjustment to a raw file.

And that goes to the original post where the author stated "Raw files don't have any inherent ISO rating of their own." IMO that is erroneous because amplification (analog/digital ISO) changes the data written into the raw file, it is not just an exif header entry like W/B and the rest are. If you make a global adjustment w/ ISO that causes areas to clip white/black in the raw file they will not be recoverable in post.
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Yup.
 
I think it's true that a camera has only one iso.
In digi cams, upping the iso is really just telling it to over expose.
 
It could be argued that there is just one thing that can truly be described as exposure and that's the shutter opening and closing, and everything else (including shutter speed) is just a variation to exposure and/or the resulting image.

On the other hand people could just learn how the three digital camera variables of shutter speed, aperture and ISO can affect a photographic image, then get on with taking some photos, instead of navel gazing and debating whether or not the use of certain terminology is scientifically accurate? (y)
 
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soupdragon said:
I think it's true that a camera has only one iso.
In digi cams, upping the iso is really just telling it to over expose.
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But back in the old film days, if you had an ISO 200 film loaded and had an opportunity for a really great image which would need more like 800 ISO, you could decide to change the development of your film to uprate it to 800, and to hell with the silly party snapshots which were already on the film. With sheet film you could decide to change ISO a bit from frame to frame. The ISO (or ASA etc.) on the packet was only what you got with the standard development. You could also change microcontrast by changing the agitation schedule of the film development.

I guess as few film shooters knew about all that kind of thing as today's digital photographers know about ISO :=)
 
SsSsSsSsSnake said:
I know Phil V was saying that the well prescibed book Understanding Exposure wasnt that.wonder if he’ll comment here
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I’m not really a big fan of the navel gazing some photographers find with exposure. I think it’s a rabbit hole that people get sucked into.

The reason I don’t like that book particularly is that it spends 200 pages talking about something that could be covered in 20 and then misses out the techniques commonly used in digital capture to manage exposure (so it misses its only job).

In many answers to a first post of ‘what do I need to learn’, the overwhelming answer is ‘exposure triangle’, it just makes photography seem like a mathematical exercise not an artistic one. IMHO it should be to just take control of what you’re focusing on, what else is in the frame and just shoot lots. People will then learn how to adjust exposure naturally once they’ve got hooked.

For us old gits, the ‘exposure triangle’ didn’t exist till fairly recently (I’d been shooting 20 years before I heard the phrase), to now see people treat it like it’s the core of photography is a bit bats.
 
Phil V said:
For us old gits, the ‘exposure triangle’ didn’t exist till fairly recently (I’d been shooting 20 years before I heard the phrase), to now see people treat it like it’s the core of photography is a bit bats.
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There's a lot spoken about photography that I find "A bit bats."...Depth of Field Calculators, I'm talking about you! :)
 
Phil V said:
I’m not really a big fan of the navel gazing some photographers find with exposure. I think it’s a rabbit hole that people get sucked into.

The reason I don’t like that book particularly is that it spends 200 pages talking about something that could be covered in 20 and then misses out the techniques commonly used in digital capture to manage exposure (so it misses its only job).

In many answers to a first post of ‘what do I need to learn’, the overwhelming answer is ‘exposure triangle’, it just makes photography seem like a mathematical exercise not an artistic one. IMHO it should be to just take control of what you’re focusing on, what else is in the frame and just shoot lots. People will then learn how to adjust exposure naturally once they’ve got hooked.

For us old gits, the ‘exposure triangle’ didn’t exist till fairly recently (I’d been shooting 20 years before I heard the phrase), to now see people treat it like it’s the core of photography is a bit bats.
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Agree about the rubbish book :)

But I don't think you can avoid a bit of science if you want to get on. Photography is both art and science, with a big element of craft skill too. Knowing what you can and can't do is important, but I certainly agree that in-depth knowledge of how it all works is not necessary to take great pictures. Having said that though, I've met a lot of very talented and famous photographers over the years through my work, and interviewed a fair few. Without exception, they all have high technical knowledge.

Exposure control is fundamental, and in fact there has always been an 'exposure triangle' even with film. It's just that with film one side of the triangle was fixed when you loaded the camera, but it's always been there and film speed pros and cons and advanced techniques frequently debated to death.
 
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I’m not suggesting you don’t need technical knowledge Richard, just that it’s rarely the most appropriate introduction to photography.

I understand that the triangle was always there, I’m just saying we didn’t use the phrase until relatively recently.
 
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