iso as an exposure variable - not.

[ironsidephoto]

I love that white balance was introduced into this a while back...like it has anything to do with exposure at all.

Make that a triple face palm. Hah.

I agree with an early poster--as long as the OP doesn't keep spreading rubbish and harming the work of other photogs, let him keep on keepin' on and keep making unsatisfactory images because he doesn't understand the value in 1/3 of his primary tools.

 

[Shane Anderson]

Tell me, how do you judge correct exposure?

Well... everything relates back to 18% reflectance (or 12% luminance, depending on which school of thought you accept). That's the benchmark.

-Pete

I'm pretty new at this but you're talking white balance, not exposure.

 

[Neil S.]

ISO is an exposure variable...in every,single shot made...every morning, afternoon,and night...bracketing via ISO index shifting and push- and pull-processing is a time-honored TRADITION in much commercial photography work where the aperture must remain at a specific f/stop value to control depth of field. Minor 1/3 and 2/3 EV value ISO adjustments are a very time-honored way to get flash exposures that hug to the right hand side of the histogram when shooting in RAW mode. The ISO value in use is a critical,basic part of the exposure equation. It is an essential factor. As in "essential", not optional.

Sorry...nice try...but the premise of this original post is totally,totally "out there" and, uh, 'wrong'...in big ol' air-quotes...

+1

Clearly Iso is one of the major factors that control exposure for digital photography.

Auto-Iso even allows the camera to scale it as needed, providing an additional means to ensure proper exposure.

The way that Iso affects exposure is really no different than that of shutter and aperture, they all control the amount of light that the sensor records in some way.

The main difference is that while shutter and aperture actually reduce or increase the incoming light, the Iso setting simply boosts the sensors ability to gather light at the cost of increased noise.

 

[Dao]

Tell me, how do you judge correct exposure?

Well... everything relates back to 18% reflectance (or 12% luminance, depending on which school of thought you accept). That's the benchmark.

-Pete

I'm pretty new at this but you're talking white balance, not exposure.

Quote from B&H "Introduction to Light Meters"


"Reflected measurements would indicate different exposures for each object. Incident measurements would indicate the same exposure for each object, to render a consistent exposure. Light meters are calibrated to assume that all subjects are of average 18% reflectance, or neutral gray. The use of the 18% neutral gray standard allows a reflected light meter to render correct readings for “average” subjects in “average” lighting situations. (The value of 18% neutral gray is also referred to as Zone V in the Zone System, an advanced black and white exposure method.)"

 

[ghpham]

Well... everything relates back to 18% reflectance (or 12% luminance, depending on which school of thought you accept). That's the benchmark.

-Pete

I'm pretty new at this but you're talking white balance, not exposure.

Quote from B&H "Introduction to Light Meters"


"Reflected measurements would indicate different exposures for each object. Incident measurements would indicate the same exposure for each object, to render a consistent exposure. Light meters are calibrated to assume that all subjects are of average 18% reflectance, or neutral gray. The use of the 18% neutral gray standard allows a reflected light meter to render correct readings for “average” subjects in “average” lighting situations. (The value of 18% neutral gray is also referred to as Zone V in the Zone System, an advanced black and white exposure method.)"

That doesn't really tell you anything. There is no such thing as a "correct" exposure. There are some general acceptance as to what a "pleasing" exposure should look like, but as an artist, you should feel free to achieve any exposure you want (other people may react unfavorably).

 

[Shane Anderson]

Quote from B&H "Introduction to Light Meters"


"Reflected measurements would indicate different exposures for each object. Incident measurements would indicate the same exposure for each object, to render a consistent exposure. Light meters are calibrated to assume that all subjects are of average 18% reflectance, or neutral gray. The use of the 18% neutral gray standard allows a reflected light meter to render correct readings for “average” subjects in “average” lighting situations. (The value of 18% neutral gray is also referred to as Zone V in the Zone System, an advanced black and white exposure method.)"

So if I shoot a gray card then it will fix my exposure and stop my highlights from blowing out?

 

[white]

Some scenes have a range of tones that exceed what film or digital is capable of recording. It's called dynamic range. Don't waste your money on gray cards. Shoot your hand, or the grass, or whatever. It's all pretty much middle gray.

 

[Dao]

I'm pretty new at this but you're talking white balance, not exposure.

Quote from B&H "Introduction to Light Meters"


"Reflected measurements would indicate different exposures for each object. Incident measurements would indicate the same exposure for each object, to render a consistent exposure. Light meters are calibrated to assume that all subjects are of average 18% reflectance, or neutral gray. The use of the 18% neutral gray standard allows a reflected light meter to render correct readings for “average” subjects in “average” lighting situations. (The value of 18% neutral gray is also referred to as Zone V in the Zone System, an advanced black and white exposure method.)"

That doesn't really tell you anything. There is no such thing as a "correct" exposure. There are some general acceptance as to what a "pleasing" exposure should look like, but as an artist, you should feel free to achieve any exposure you want (other people may react unfavorably).

Did you noticed that the other poster thought the gray card was for white balance only so I point out it is for exposure as well?

 

[Dao]

Quote from B&H "Introduction to Light Meters"


"Reflected measurements would indicate different exposures for each object. Incident measurements would indicate the same exposure for each object, to render a consistent exposure. Light meters are calibrated to assume that all subjects are of average 18% reflectance, or neutral gray. The use of the 18% neutral gray standard allows a reflected light meter to render correct readings for “average” subjects in “average” lighting situations. (The value of 18% neutral gray is also referred to as Zone V in the Zone System, an advanced black and white exposure method.)"

So if I shoot a gray card then it will fix my exposure and stop my highlights from blowing out?

It depends on the particular situation and what you want to accomplish. If you ran into situation like blown out highlight, create a new thread with the sample photos and tell us what you want to achieve, we may be able to give you some opinion on that.

 

[timethief]

any change in any one of the 3 elements (AP/SH/ISO) will cause a predictable impact on the other and consequently impact the final image.

 

[Christie Photo]

Tell me, how do you judge correct exposure?

Well... everything relates back to 18% reflectance (or 12% luminance, depending on which school of thought you accept). That's the benchmark.

-Pete

I'm pretty new at this but you're talking white balance, not exposure.

Yeah... you are new at this.

A grey card reflects approximately 18% of the light that falls onto it. And yes... it is also considered to be neutral in color and can be used for white balance.

I want to re-emphasise the word "benchmark." A benchmark is an anchor used as a point to which everything else relates.

Think about the room you are in right now. Is it too warm? Too cool? To answer this question, we first need something to which we can relate. I suspect if you want to store ice cream, the room is too warm. Similarly, if you want to incubate eggs, I suspect the room is too cool.

For quite some time now, the benchmark used in photography is 18% reflectance. So if we find our developer is too warm, we mean it's too warm to achieve a negative to produce 18% gray. Or if the development time is too short, it means too short to achieve 18% gray. It's the same with exposure. Simply put, the meter in your camera is telling you how to achieve 18% gray. So if you put a grey card into a scene you want to photograph and read the light reflecting off the card, you will have proper exposure for that light.

Of course, this is a very simple, general way of thinking about the process. But it will get you very close. There are other factors that will come into play that you will learn with experience, such as angle of reflectance.

ISO too relates back to 18% reflectance.

Since I began working with digital imaging, I favor an exposure that's just a bit under 18%. This is where personal style and desired results come in.

I hope this helps.

-Pete