Is the goal to have the lowest ISO possible

[MichaelRyanSD]

I realize given all the possibilities that the answer is no, but hypothetically, all other things being equal, should the ISO be the last thing I adjust to allow the light in. Maybe a better way to ask, should ISO be the last thing I go to to get the right exposure for the shot?

 

[D-B-J]

Depends. Do you need to freeze action? Shutter speed is the last thing to change. Do you need to have as much as possible in focus? Aperture is the last thing to change. Do you not care? Change ISO last. But yes, in a perfect world, I'd prefer to up the ISO only if I have to.

Best,
Jake

 

[robbins.photo]

I realize given all the possibilities that the answer is no, but hypothetically, all other things being equal, should the ISO be the last thing I adjust to allow the light in. Maybe a better way to ask, should ISO be the last thing I go to to get the right exposure for the shot?

I guess you might get a lot of different answers here based on everyone's preferred method. As for me I like aperture priority mode, so generally I'll adjust the aperture to get the desired depth of field or as close to it as I think I can get based on the lighting conditions, then I adjust the ISO until I get what I consider to be an acceptable shutter speed for the shot. Works fairly well for me, but I'm assuming of course that other folks probably have a variety of methods. I guess my thought is as long as you get the shot, that's all that really matters.

 

[manaheim]

I try to keep the ISO as low as possible... while still getting the image I need. ISO is the last compromise I'm willing to make because of the issues it creates with noise and color accuracy.

And I'm saying that as a person who runs a Nikon D800, which is arguably one of the high ISO kings.

 

[runnah]

It's all about knowing your camera and your intended shot. Once you know that you can make sacrifices from the 3 factors of exposure.

 

[apaflo]

I realize given all the possibilities that the answer is no, but hypothetically, all other things being equal, should the ISO be the last thing I adjust to allow the light in. Maybe a better way to ask, should ISO be the last thing I go to to get the right exposure for the shot?

Here's a mind boggling thought... ISO has no direct effect on exposure.

Exposure is changed only by two things: one is how much light comes through the lens and the other is how long that light is allowed to hit the sensor. Basically aperture and shutter speed.

That results in a set amount of analog signal being generated by the electronic sensor. Nothing else changes that.

But after that analog signal is generated the camera does two things which may change the brightness of the recorded data. That doesn't really change the "exposure", but many people don't realize it actually is different. First, the signal might be amplified by an analog device, and second it is digitized with an Analog-Digital-Converter. In the process of being digitized, or afterwards, the digital data can be amplified too, just as the analog signal was. The significance to your original question is that the analog, the ADC amplification, and the post-ADC amplification each have different characteristics and all of them result in changes to brightness but otherwise lower quality for the image compared to what would have happened if the exposure had been increased. When done in the camera those are all called an increase in ISO (sensitivity to light, or how bright the recorded data is).

In that respect, yes we always want to use a lower ISO (as long as it is above the native ISO of the sensor and does not need amplification). However... there is always a catch! Sometimes we like to set aperture and/or shutter time for artistic effects other than simply image quality. Hence we may want to use both an f/stop and a shutter speed that does not allow ISO 200. Then the queston becomes one of exactly what is the tradeoff for use of ISO 400, or even ISO 8000 perhaps. And is that trade worth taking.

Genarally the difference with higher ISO is lower dynamic range, which necessarily means higher noise in the shadows. Sometimes that is acceptable, sometimes it's not. Depends on how the picture is used.

 

[manaheim]

I realize given all the possibilities that the answer is no, but hypothetically, all other things being equal, should the ISO be the last thing I adjust to allow the light in. Maybe a better way to ask, should ISO be the last thing I go to to get the right exposure for the shot?

Here's a mind boggling thought... ISO has no direct effect on exposure.

Exposure is changed only by two things: one is how much light comes through the lens and the other is how long that light is allowed to hit the sensor. Basically aperture and shutter speed.

That results in a set amount of analog signal being generated by the electronic sensor. Nothing else changes that.

But after that analog signal is generated the camera does two things which may change the brightness of the recorded data. That doesn't really change the "exposure", but many people don't realize it actually is different. First, the signal might be amplified by an analog device, and second it is digitized with an Analog-Digital-Converter. In the process of being digitized, or afterwards, the digital data can be amplified too, just as the analog signal was. The significance to your original question is that the analog, the ADC amplification, and the post-ADC amplification each have different characteristics and all of them result in changes to brightness but otherwise lower quality for the image compared to what would have happened if the exposure had been increased. When done in the camera those are all called an increase in ISO (sensitivity to light, or how bright the recorded data is).

Whether that's right or wrong, it's mostly just semantics. It doesn't really alter the advice that is being provided. From a purely practical level, ISO has a negative effect on image quality. How that negative effect gets there mechanically is interesting, but not relevant to the question.

 

[runnah]

Here's a mind boggling thought... ISO has no direct effect on exposure. Exposure is changed only by two things: one is how much light comes through the lens and the other is how long that light is allowed to hit the sensor. Basically aperture and shutter speed. That results in a set amount of analog signal being generated by the electronic sensor. Nothing else changes that. But after that analog signal is generated the camera does two things which may change the brightness of the recorded data. That doesn't really change the "exposure", but many people don't realize it actually is different. First, the signal might be amplified by an analog device, and second it is digitized with an Analog-Digital-Converter. In the process of being digitized, or afterwards, the digital data can be amplified too, just as the analog signal was. The significance to your original question is that the analog, the ADC amplification, and the post-ADC amplification each have different characteristics and all of them result in changes to brightness but otherwise lower quality for the image compared to what would have happened if the exposure had been increased. When done in the camera those are all called an increase in ISO (sensitivity to light, or how bright the recorded data is). In that respect, yes we always want to use a lower ISO (as long as it is above the native ISO of the sensor and does not need amplification). However... there is always a catch! Sometimes we like to set aperture and/or shutter time for artistic effects other than simply image quality. Hence we may want to use both an f/stop and a shutter speed that does not allow ISO 200. Then the queston becomes one of exactly what is the tradeoff for use of ISO 400, or even ISO 8000 perhaps. And is that trade worth taking. Genarally the difference with higher ISO is lower dynamic range, which necessarily means higher noise in the shadows. Sometimes that is acceptable, sometimes it's not. Depends on how the picture is used.

You are over thinking it. I turn the ISO dial and my picture gets lighter, therefore ISO affects exposure.

Don't confuse the op.

 

[apaflo]

I realize given all the possibilities that the answer is no, but hypothetically, all other things being equal, should the ISO be the last thing I adjust to allow the light in. Maybe a better way to ask, should ISO be the last thing I go to to get the right exposure for the shot?

Here's a mind boggling thought... ISO has no direct effect on exposure.

Exposure is changed only by two things: one is how much light comes through the lens and the other is how long that light is allowed to hit the sensor. Basically aperture and shutter speed.

That results in a set amount of analog signal being generated by the electronic sensor. Nothing else changes that.

But after that analog signal is generated the camera does two things which may change the brightness of the recorded data. That doesn't really change the "exposure", but many people don't realize it actually is different. First, the signal might be amplified by an analog device, and second it is digitized with an Analog-Digital-Converter. In the process of being digitized, or afterwards, the digital data can be amplified too, just as the analog signal was. The significance to your original question is that the analog, the ADC amplification, and the post-ADC amplification each have different characteristics and all of them result in changes to brightness but otherwise lower quality for the image compared to what would have happened if the exposure had been increased. When done in the camera those are all called an increase in ISO (sensitivity to light, or how bright the recorded data is).

Whether that's right or wrong, it's mostly just semantics. It doesn't really alter the advice that is being provided. From a purely practical level, ISO has a negative effect on image quality. How that negative effect gets there mechanically is interesting, but not relevant to the question.

In fact none of it is semantics. All of it is technically correct. All of it directly affects the image quality of capture data. And until a photographer does understand the significance of it (though not necessarily the technical details) their photography will be limited by that lack of understanding.

 

[apaflo]

You are over thinking it. I turn the ISO dial and my picture gets lighter, therefore ISO affects exposure.

Don't confuse the op.

When you shoot with a film camera, do you say that changing to higher speed film is a change in exposure? Or do you change film and then change the exposure to match the different ISO...

Lets not confuse people with incorrect definitiions, such as saying anything that makes an image brigher is a change in exposure. Keep in mind that exposure with film was exactly the same as is exposure with digital.

 

[runnah]

When you shoot with a film camera, do you say that changing to higher speed film is a change in exposure? Or do you change film and then change the exposure to match the different ISO... Lets not confuse people with incorrect definitiions, such as saying anything that makes an image brigher is a change in exposure. Keep in mind that exposure with film was exactly the same as is exposure with digital.

What are you going on about? Yes of course it changes the exposure. Because I am EXPOSING the film/sensor for a different amount of time based on the desired EXPOSURE.

That is what exposure means.

 

[MichaelRyanSD]

I appreciate the technical explanation of ISO, and I realize as most beginners should, the difference between the analog and digital inputs in regards to exposure. I just didn't make a mention of it in the original post for the sake of the question, sort of a "keep it simple stupid" question.

Thank you though, and everyone else. You all sort of confirmed what I was thinking, like I mentioned, there are too many variables to account for when adjusting the settings, but given all things being equal, we should adjust the ISO last, since it essence, it degrades the picture.

 

[apaflo]

What are you going on about? Yes of course it changes the exposure. Because I am EXPOSING the film/sensor for a different amount of time based on the desired EXPOSURE.

That is what exposure means.

Yes, a "different amount of time". Changing the film didn't change the time. When you changed the shutter speed it change the time, and thus the exposure.

 

[JerryLove]

How soon do real ISO problems kick in? Obviously at the upper range there's significant noise: but on a modern body (sat a T2i), is there really much quality difference between ISO100, ISO200, and ISO400?

 

[Derrel]

I realize given all the possibilities that the answer is no, but hypothetically, all other things being equal, should the ISO be the last thing I adjust to allow the light in. Maybe a better way to ask, should ISO be the last thing I go to to get the right exposure for the shot?

The goal is to get the best photos. All other things are never equal, and to boot, you're asking for a practical answer about a hypothetical question? Uh...where to start.

Accept that not everything is equal. Ever. Photography, and the world, vary. A lot. Sometimes, ISO selection is a critical factor in success or failure. Late in the afternoon, as twilight comes, if you want to do stop-action photography, OR if you have a slow lens (say an f/5.6 max. aperture zoom), you will want to BEGIN WITH an elevated ISO level, and work from that starting point.

In low-light sports shooting scenarios, I will often START with the premise that ISO 1600 is **the best** place to begin, and will work on exposure with that as a given starting point. With new cameras, ISO 3,200, 6,400, and 12,800 are ALL actually pretty usable with the better, newer cameras, especially for smaller images and web use.

In bright-light situations where you are going to shoot fill-flash, I would begin with the LOWEST ISO your camera offers, since f/16 at the ISO in use is the "sunny 16" exposure, so with a camera having a 1/200 top flash synch speed, and a base ISO of 100, at the base ISO, the exposure for the sunlight will be 1/100 second at f/16, up to 1/200 second at f/11. If the camera offers a LOW setting, such as an equivalent to ISO 50, you might want to start with that ISO. (suffering only a slight loss in dynamic range, but no big deal).

********

If you come right down to a "general idea", I would say under many situations, ISO 400 offers the best mix of ISO speed, shutter speed, depth of field, and FLEXIBILITY over exposures that are possible. It might have some loss of DR and color richness, but the newest sensors are still excellent, and again, the goal is to be able to make the best pictures...not concerning yourself with a bunch of technical B.S. and arcane, esoteric crap that some people fixate on. A slight bit of noise or a slight loss of total DR or a slight loss of richness in color is better than a low-noise, low-ISO but a bunch of smeary, blurred images.