Using ISO settings less than ISO 100

Lonnie1212

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Does anyone intentionally set their camera to use an ISO less than 100? In the past I have used ISO 100 as much as possible. Now I have a camera with a lower than 100 ISO option. To my understanding the lower ISO will create a less grainy picture under the right conditions. I do understand that it is not always possible to use a lower ISO. But in those conditions where using a lower ISO is possible, how low has anyone successfully dropped the ISO? How did the pictures turn out and do you favor using those settings?

Thank you,

Lonnie
 

petrochemist

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Your understanding is not perfectly correct. Using very high ISO certainly creates noise (as does underexposing). The ISO settings lower than the senors base ISO can actually give rise to more noise (but I doubt you'll ever see it).

Normally I stick between ISO 100 & ISO 800, but if I need longer exposures I might drop to ISO 50 if the body will let me (most of mine won't). In dark conditions I'll go much higher than 800, but try to avoid going to the highest ISO settings the body supports. The very highest settings tend to be reserved for test shots to judge exposure when the meter struggles due to very low light (stars...).
 

Soocom1

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Ok First a recap:
ISO is a measure of light sensitivity.
It was previously known either as ASA or DIN. American Standard Association and Deutsches Institut für Normung respectively.

This is a standard of how fast the film is in being exposed. A 6, 12, 25 and 50 ASA was standard for extremely high grain images. but the trade off was super slow. The higher the number the faster the film.
The lower the number the slower but finer grain
these numbers were absorbed into the ISO standards under the ISO system.
Digital doesnt work this way. I stead it read light intensity rather than react and chemically change as silver does. The numbers were established to mimic the film numbers so a new convintoon did not have to be created or interpreted

Digital shooting atower ISO behaves differently than film but similar results are had Usuly more comete i formation being collected by the sensor and thus a better rendeition of the image being shot.

But again the same trade off. Slower speed, slower shutter.
 

Braineack

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When iso 64 is base, yes.
 

vintagesnaps

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I don't very often. I hardly ever shoot lower film speeds. Depends on what you're doing.
 

Ysarex

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Nikon does not apply any different signal processing to extended ISOs below base. Implementation of the ISO exposure to output image lightness mapping is handled entirely in the EXPEED processor. As a result the same exposure (shutter speed + f/stop) at base ISO and at one of the extended ISOL setting will produce identical raw files.

The extended ISOL settings do of course alter the camera's metering and if you follow the camera metering either manually or by using one of the auto/semi-auto exposure modes you're going to increase exposure. That increased exposure will give you an image with slightly less noise but you also run the risk of reaching the sensor's clipping threshold and nuking some highlights. The follow-up processing in the EXPEED processor won't help those nuked highlights -- so be sure.

Joe
 

AlanKlein

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Nikon does not apply any different signal processing to extended ISOs below base. Implementation of the ISO exposure to output image lightness mapping is handled entirely in the EXPEED processor. As a result the same exposure (shutter speed + f/stop) at base ISO and at one of the extended ISOL setting will produce identical raw files.

The extended ISOL settings do of course alter the camera's metering and if you follow the camera metering either manually or by using one of the auto/semi-auto exposure modes you're going to increase exposure. That increased exposure will give you an image with slightly less noise but you also run the risk of reaching the sensor's clipping threshold and nuking some highlights. The follow-up processing in the EXPEED processor won't help those nuked highlights -- so be sure.

Joe
So what's the point of the lower than "base" ISO?
 

Ysarex

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Nikon does not apply any different signal processing to extended ISOs below base. Implementation of the ISO exposure to output image lightness mapping is handled entirely in the EXPEED processor. As a result the same exposure (shutter speed + f/stop) at base ISO and at one of the extended ISOL setting will produce identical raw files.

The extended ISOL settings do of course alter the camera's metering and if you follow the camera metering either manually or by using one of the auto/semi-auto exposure modes you're going to increase exposure. That increased exposure will give you an image with slightly less noise but you also run the risk of reaching the sensor's clipping threshold and nuking some highlights. The follow-up processing in the EXPEED processor won't help those nuked highlights -- so be sure.

Joe
So what's the point of the lower than "base" ISO?

For someone who wants the JPEG from the camera and would benefit from either a slower shutter speed (eg. moving water photo) or larger aperture (eg. blurrier background).

If you're saving and processing raw files and understand what the camera is doing it's pointless.

Joe
 

Soocom1

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The neat thing about digital is that it is recording light intensity. Not chemically reacting as I stated earlier. I shoot my 5D regularly at 50 ISO especially on bright days doing landscape. The slower speeds also allow for more spicific effects on water, clouds etc.

Slower speeds also men that apatures are a bit more controllable.
 

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I rarely set my Canon to the L setting which I believe is ISO 50 because I do not fully understand what it is really doing. The manual suggests that this is some sort of "synthetic" ISO and not really 50. Of course isn't everything digital "synthetic"? I only use it if the scene is very bright and I want a longer exposure.

Maybe someone here can provide clarity on what the L setting really does.
 

Soocom1

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Exactly that. Low or more accurately ISO 50.
 

Ysarex

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I rarely set my Canon to the L setting which I believe is ISO 50 because I do not fully understand what it is really doing. The manual suggests that this is some sort of "synthetic" ISO and not really 50. Of course isn't everything digital "synthetic"? I only use it if the scene is very bright and I want a longer exposure.

Maybe someone here can provide clarity on what the L setting really does.

Canon does the same as Nikon as I described above. Setting the ISO to L causes the camera meter to calculate an exposure increase compared to the ISO 100 setting. If you follow the meter or use the camera in an auto mode that exposure increase will be applied (more light on the sensor). The camera then processes the image creating both a raw file and JPEG image. The camera does nothing different creating the raw file than it does with the ISO set to 100 -- you get a raw file that indicates more exposure. Likewise if you put the camera in Manual mode and take the same exposure (same shutter speed & aperture) at both ISO 100 and ISO L you get two identical raw files even though the ISO changes. When the camera creates the JPEG image the DIGIC processor adjusts the lightness of the JPEG for the ISO L exposure.

Joe
 

Ysarex

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When the camera creates the JPEG image the DIGIC processor adjusts the lightness of the JPEG for the ISO L exposure.

Sounds similar to increasing brightness in post.

It is -- although in this case the camera is decreasing brightness in post. Everything a camera does to implement ISO for an image is technically done "in post" in that it all occurs after the exposure is taken.

Joe
 

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