Need Help with iso and exposures

[amolitor]

Think of it like a bridge.. No, wait. Don't.

 

[Helen B]

Or a pillow - a soft, fluffy pillow with a little kitten playing on it.

 

[Rafterman]

Here, this should give you all the answers you need: Google Image Search

I advise you save and/or print some of those for future quick reference.

In a nutshell though, doubling the ISO will allow you to cut your shutter speed in half at the same aperture, or close your aperture by one full stop at the same shutter speed.

For example, these settings will essentially take 4 pictures that all look similar to each other (if all other factors remain the same):

• ISO 100, 1/250th, f/4
• ISO 200, 1/250th, f/5.6
• ISO 100, 1/500th, f/2.8
• ISO 200, 1/500th, f/4

 

[Jad]

Corrected terminology, Thanks Helen.
ISO or ASA is based on a factor of two, as are all of the other elements of the exposure triangle (shutter speed, aperture and sensitivity), so that when a number doubles, so does the sensitivity. Only the apeture and the shutter speed controls the amount of light coming into the camera.

 

[480sparky41 40]

........... So the best way to express a change from ISO 100 to 400 would be a (4x) or 400% increase in light sensitivity required to make an image on either film(less silver grains in the film) or a sensor (fewer pixels needed to record an image). Only the apeture and the shutter speed controls the amount of light coming into the camera. SPAM LINK DELETED

Sorry, but when you use a higher ISO film, you are increasing the number of silver grains in the emulsion, not using less........... and when you increase the ISO on a digital camera you don't use fewer pixels, you are simply increasing the amount of digital processing done to the data produced by those pixels.

 

[480sparky41 40]

............Your digital camera lets say is rated at 20 megapixels. It will only use the full megapixel capacity of the camera when used at the lowest ISO rating. You could turn your $3,000 camera into a 1 megapixel camera if you put the ISO to the highest setting. Thems just the facts my friend JAD

Um........... no.

A 20mp camera will produce a 20mp image at ISO 1 or ISO 1,000,000.

 

[Helen B]

........... So the best way to express a change from ISO 100 to 400 would be a (4x) or 400% increase in light sensitivity required to make an image on either film(less silver grains in the film) or a sensor (fewer pixels needed to record an image). Only the apeture and the shutter speed controls the amount of light coming into the camera. SPAM LINK DELETED

Sorry, but when you use a higher ISO film, you are increasing the number of silver grains in the emulsion, not using less........... and when you increase the ISO on a digital camera you don't use fewer pixels, you are simply increasing the amount of digital processing done to the data produced by those pixels.

You are wrong in what you have stated. A film made with a ISO 100 rating has more silver in the emulsion than the a film rated at 400. Less silver, less light need to record an image.
Your digital camera lets say is rated at 20 megapixels. It will only use the full megapixel capacity of the camera when used at the lowest ISO rating. You could turn your $3,000 camera into a 1 megapixel camera if you put the ISO to the highest setting. Thems just the facts my friend JAD

It's mostly the size of the silver halide crystal or grain (not silver grains) that affects film sensitivity, not the amount. The larger the crystal, the more sensitive it is because, in simple terms, the number of photons required to create a stable latent image centre is largely independent of crystal size. The larger the crystal, the more photons it can catch.

 

[Jad]

............Your digital camera lets say is rated at 20 megapixels. It will only use the full megapixel capacity of the camera when used at the lowest ISO rating. You could turn your $3,000 camera into a 1 megapixel camera if you put the ISO to the highest setting. Thems just the facts my friend JAD

Um........... no.

A 20mp camera will produce a 20mp image at ISO 1 or ISO 1,000,000.

Sorry for the confusion

 

[Jad]

Sorry, but when you use a higher ISO film, you are increasing the number of silver grains in the emulsion, not using less........... and when you increase the ISO on a digital camera you don't use fewer pixels, you are simply increasing the amount of digital processing done to the data produced by those pixels.

You are wrong in what you have stated. A film made with a ISO 100 rating has more silver in the emulsion than the a film rated at 400. Less silver, less light need to record an image.
Your digital camera lets say is rated at 20 megapixels. It will only use the full megapixel capacity of the camera when used at the lowest ISO rating. You could turn your $3,000 camera into a 1 megapixel camera if you put the ISO to the highest setting. Thems just the facts my friend JAD

It's mostly the size of the silver halide crystal or grain (not silver grains) that affects film sensitivity, not the amount. The larger the crystal, the more sensitive it is because, in simple terms, the number of photons required to create a stable latent image centre is largely independent of crystal size. The larger the crystal, the more photons it can catch.

Again you are correct Helen. It is mainly the clumping of the silver halide crystals in the emulsion that establishes the sensitivity of the film and the grain pattern. I still think that there is more silver in a low speed film when compared to the ultra high speed film. You are not going to make me look like a monkey in a zoo again, are you?

 

[Helen B]

Sorry, I only meant it as a sort of clarification.

 

[Joves]

............Your digital camera lets say is rated at 20 megapixels. It will only use the full megapixel capacity of the camera when used at the lowest ISO rating. You could turn your $3,000 camera into a 1 megapixel camera if you put the ISO to the highest setting. Thems just the facts my friend JAD

Um........... no.

A 20mp camera will produce a 20mp image at ISO 1 or ISO 1,000,000.

Sorry Boss, but I think you are wrong with your statement. I am not much of a techno geek when it comes to shop talk about camera equipment. If the mega pixel count doesn't change with the ISO setting, then why is there more noise in the high ISO images compared to the ISO 100? I am no expert, but I still think to make the sensor more sensitive to less light means there are less pixels exposed at the higher settings. If what you say is true then there is no advantage to image quality using a slow setting of ISO 100.

Actually it is a case of using all of the pixels. In digital you are merely changing the gain on the sensor through the amplifier to make it more sensitive to light. This is why you end up getting noise, more gain equals more amplifier noise. Digital really has no relation to film in its ISO settings and performance. The ISO ratings are merely a equivalent of a known, and long standing value.
As Helen stated for film it is the size of the silver grains that makes it more sensitive to light. Which is why the higher the ISO the grainier the photo, which is akin to noise on a digital image. Also it is why you were better off pushing your film than buying higher ISO films back in the day.

 

[Jad]

Um........... no.

A 20mp camera will produce a 20mp image at ISO 1 or ISO 1,000,000.

I am not much of a techno geek when it comes to shop talk about camera equipment. If the mega pixel count doesn't change with the ISO setting, then why is there more noise in the high ISO images compared to the ISO 100? I am no expert, but I still think to make the sensor more sensitive to less light means there are less pixels exposed at the higher settings. If what you say is true then there is no advantage to image quality using a slow setting of ISO 100.

Actually it is a case of using all of the pixels. In digital you are merely changing the gain on the sensor through the amplifier to make it more sensitive to light. This is why you end up getting noise, more gain equals more amplifier noise. Digital really has no relation to film in its ISO settings and performance. The ISO ratings are merely a equivalent of a known, and long standing value.
As Helen stated for film it is the size of the silver grains that makes it more sensitive to light. Which is why the higher the ISO the grainier the photo, which is akin to noise on a digital image. Also it is why you were better off pushing your film than buying higher ISO films back in the day.

That makes sense so I will take your word for it. I just know from a picture taking stand point a high ISO setting makes my 5D look like a low quality point and shoot camera. I have always stayed with a rating of 100 for film and digital and rarely have I ever touch ISO setting on my digital equipment.

 

[Jad]

Sorry, I only meant it as a sort of clarification.

I am only joking with you. Your answers are very accurate and informative.