ISO

[brandolsx]

I get the concepts of Aperture and F-Stop, but I keep reading in places to change the ISO under certain conditions. What does changing the ISO do? Maybe just a short background and run down on ISO. Thanks!

 

[o hey tyler]

Increasing the ISO makes the sensor more sensitive to light. Raising the ISO also makes for more digital noise in your images, but it allows you to take photos with less light.

Pretty basic rundown. Not going to type up a whole big thing on my phone.

This should help: http://digital-photography-school.com/iso-settings

 

[fjrabon]

Film speed - Wikipedia, the free encyclopedia

 

[brandolsx]

Increasing the ISO makes the sensor more sensitive to light. Raising the ISO also makes for more digital noise in your images, but it allows you to take photos with less light.

Pretty basic rundown. Not going to type up a whole big thing on my phone.

This should help: ISO Settings in Digital Photography

Thanks Dood. Thats really all I needed for a basic rundown to understand. Does most DSLR's set this itself most of the time until you put it in manual mode?

 

[Jaemie]

Thanks for asking this question. For a long time I've been wondering what happened to ASA and how it became ISO. Thanks to the links, now I know.

 

[Judobreaker]

Does most DSLR's set this itself most of the time until you put it in manual mode?

No.
I'm honestly not even sure my D7000 has an auto ISO option. It might have but I haven't found it yet (and to be honest I don't intend to find it either as I don't want it).

 

[Solarflare]

Yes Nikon cameras have an Auto ISO setting.

You can set it on/off, you can set a maximum ISO, and you can set a minimal shutter speed.

I really love this automatic, except it would be really more comfortable if there was a direct dial instead of having to do menu surfing.

 

[fjrabon]

Yes Nikon cameras have an Auto ISO setting.

You can set it on/off, you can set a maximum ISO, and you can set a minimal shutter speed.

I really love this automatic, except it would be really more comfortable if there was a direct dial instead of having to do menu surfing.

You love auto ISO? ISO is the one thing that I can never deal with having auto. I can shoot in shutter priority, aperture priority, but auto ISO drives me crazy. Your pictures get these wild jumps in feel that is really annoying and very difficult to fix in post.

 

[3bayjunkie]

Yes the d7000 has an auto iso and no i would never consider using it unless you really have no clue about cameras. My wife uses it on her canon is40 because she doesn't want to know what shutter speed aperture or iso is. And she really has no idea so for her she has to use it. But otherwise it is better to chose it manually. Use aperture priority or shutter priority mode.

Usually outside you can get away with 100-400 and inside 800-3200 iso.

 

[480sparky41 41]

Increasing the ISO makes the sensor more sensitive to light. ...........

Technically, incorrect.

Raising the ISO simply changes the algorithms used by the camera's processor on the data the sensor produces. The sensor will 'see' the exact same thing, whether the ISO is set to 50 or 512,000.

 

[fjrabon]

Increasing the ISO makes the sensor more sensitive to light. ...........

Technically, incorrect.

Raising the ISO simply changes the algorithms used by the camera's processor on the data the sensor produces. The sensor will 'see' the exact same thing, whether the ISO is set to 50 or 512,000.

Given this, I've never understood why you can't change ISO in post if you shoot RAW? I mean I guess I understand that you can somewhat, but it almost seems to me like ISO should be 100% adjustable in post.

 

[480sparky41 41]

Increasing the ISO makes the sensor more sensitive to light. ...........

Technically, incorrect.

Raising the ISO simply changes the algorithms used by the camera's processor on the data the sensor produces. The sensor will 'see' the exact same thing, whether the ISO is set to 50 or 512,000.

Given this, I've never understood why you can't change ISO in post if you shoot RAW? I mean I guess I understand that you can somewhat, but it almost seems to me like ISO should be 100% adjustable in post.

If you could, then you would need to adjust either the shutter speed or aperture in post to maintain 'correct' exposure..... something that's rather hard to do (unless your DeLorean can do 88MPH). But many raw processors allow you some exposure adjustment. Capture NX2 lets me adjust 2 stops either way.

Remember, sensors just 'count photons'. If there's no photons to count, the pixel is rendered black. If the photoreceptor on the sensor is overloaded, it returns a white. The only way to change that in the field is to adjust the shutter or aperture (or use an ND filer). Being able to change the ISO, whether in the field or in post, would make no difference.

 

[HughGuessWho99 14]

Given this, I've never understood why you can't change ISO in post if you shoot RAW? I mean I guess I understand that you can somewhat, but it almost seems to me like ISO should be 100% adjustable in post.

Because its about the electronics of the camera. It is what is was. You can't take a picture of a fish and change it into a dog in ACR. You can't take a picture at ISO 4000 and change it to ISO 100 in ACR.

 

[unpopular]

Increasing the ISO makes the sensor more sensitive to light. ...........

Technically, incorrect.

Raising the ISO simply changes the algorithms used by the camera's processor on the data the sensor produces. The sensor will 'see' the exact same thing, whether the ISO is set to 50 or 512,000.

Also incorrect. ISO changes the analog gain of the amplifier, rather than applying digital algorithms to recorded data. This is done on the analog side of the camera, not the digital side. There are no algorithms involved. Changing ISO is not the same in the RAW processor as just boosting up the "exposure" slider in your raw image processor.

 

[fjrabon]

Given this, I've never understood why you can't change ISO in post if you shoot RAW? I mean I guess I understand that you can somewhat, but it almost seems to me like ISO should be 100% adjustable in post.

Because its about the electronics of the camera. It is what is was. You can't take a picture of a fish and change it into a dog in ACR. You can't take a picture at ISO 4000 and change it to ISO 100 in ACR.

I understand that. My point is that ISO doesn't actually change what the sensor records (or at least that's the way I interpreted what Sparky said). ISO doesnt make the sensor more sensitive, it just changes how the image was processed, which, as I've understood RAW, it doesn't make use of the processing, it simply records what the settings were. This is just like how white balance is more or less completely adjustable in post if you shoot RAW, because while the camera does note what it thought the settings were white balance wise, it doesn't change what the sensor recorded.

Shutter speed and aperture are physical characteristics of the lens, while ISO is about how the image was processed. Given that, it seems like to me you should be able to completely adjust 100% in post. ie it seems like if you shot an image at ISO 100 that was 4 stops underexposed, you should be able to bump it up to ISO 400 in post, and it would look exactly the same. I've never 100% understood why that isn't the case. Sure, we can basically do it for 2 stops, and everything mostly looks the same, but much more than that, and you see way more noise than you would if you had shot it at a higher ISO in camera.