This is a handout that I came up with for one of my photography classes I teach (Page 2): Before commenting on my statement at the bottom of my handout, please take the time to read my...

grandpaw

Before commenting on my statement at the bottom of my handout, please take the time to read my two replies and it might save you time in trying to explain why it is a wrong statement. I addressed this in my replies.

Charlie157 Loc: San Diego, CA

rmalarz wrote:

Your statement is true. However, exposure deals only with aperture and shutter speed. If one wishes to capture an image then an photosensitive material becomes involved, and, thus, its sensitivity has to be taken into account.
--Bob

I assumed that when talking about iso, aperture and shutter speed we are talking about the use of photo sensitive material. Maybe I'm misunderstanding your response

Charlie 157

R.G. Loc: Scotland

grandpaw wrote:

.....it will amplify the amount of light.......

You risk causing confusion by wording it like that, and it's still wrong. ISO amplifies the sensor signal. You should keep your explanations factual.

JD750 Loc: SoCal

grandpaw wrote:

This is a handout that I give out in my class and explain all of this when I hand it out. I think you can see what I am trying to get across is how the settings affect each other. I try and make it a simple as to understand as possible. If I would have left out the last three words, "into your camera", and everyone would be happy.

Very nice visual guide.

As to the kerfuffle over the wording, you might consider saying “it will double the exposure value (ev).”

srt101fan

How the ISO settings in a digital camera affect the image file is a complex topic. I subscribe to the comments UHH member Ysarex has made on this topic, most recently in:

https://www.uglyhedgehog.com/t-710872-1.html

ISO does not change the sensitivity of the sensor.

And changing ISO does not affect the exposure directly, it just changes the amount of light required for a "correct" exposure. Based on that, the camera (in an automatic mode) or the photographer (manually) change the aperture or shutter speed to change the exposure. Granted, this part is a bit of dabbling in semantics.

I wish people would quit bringing film and ASA into these discussions. It just adds to the confusion.

JD750 Loc: SoCal

srt101fan wrote:

ISO does not change the sensitivity of the sensor.

And changing ISO does not affect the exposure directly, it just changes the amount of light required for a "correct" exposure.

I wish people would quit bringing film and ASA into these discussions. It just adds to the confusion.

Increasing ISO changes the gain of the circuit which effectively is the same as increasing the sensitivity of the sensor.

The downside is increasing the circuit gain also increases digital noise in the resultant image.

The comparison to film ASA is fair as similar effects are observed when increasing or pushing film ASA. I’m sorry if that confuses you.

srt101fan

JD750 wrote:

Increasing ISO changes the gain of the circuit which effectively is the same as increasing the sensitivity of the sensor.

The downside is increasing the circuit gain also increases digital noise in the resultant image.

The comparison to film ASA is fair as similar effects are observed when increasing or pushing film ASA. I’m sorry if that confuses you.

Please read Ysarex's comments....

BebuLamar

grandpaw wrote:

You are technically correct that ISO doesn't change the amount of light coming into the camera but it will amplify the amount of light or cut the amplification in half that is produced by the aperture and or shutter speed by moving to the left or right.

ISO whether it's the sensor amplification or the actual sensitivity of the film is not the exposure but changing it would require a different exposure to get the correct brightness. So instead of 3 items you should make it 2 sides. One side is the aperture and shutter speed the other is the ISO.

Lukabulla

But isn't ISO the cornerstone of any Speed / Aperture settings ?
Before any adjustments to exposure one must look at what iso has been chosen .

srt101fan

Lukabulla wrote:

But isn't ISO the cornerstone of any Speed / Aperture settings ?
Before any adjustments to exposure one must look at what iso has been chosen .

Not necessarily. I mostly have my camera set to the "M" (Manual) mode with Auto ISO turned on. I adjust shutter speed and aperture and then look at what ISO the camera selected.

rmalarz Loc: Tempe, Arizona

For photographic exposure, yes, you are correct. When I teach intro to photograpy, I use a balance scale where the weight upon one side is ISO and weights representing aperture and shutter speed are placed on the other side.
--Bob

BebuLamar wrote:

ISO whether it's the sensor amplification or the actual sensitivity of the film is not the exposure but changing it would require a different exposure to get the correct brightness. So instead of 3 items you should make it 2 sides. One side is the aperture and shutter speed the other is the ISO.

Country Boy Loc: Beckley, WV

Great teaching tool!

jerryc41 Loc: Catskill Mts of NY

Nice one

pgiraudin3

Then the next thing to teach is why you choose to move either the aperture or shutter speed to the left or right. Aperture can control depth of field, and shutter speed can control motion...stop action or create an intentional blur. Photographing a waterfall with a fast shutter speed gives the illusion of ice...not necessarily what you want.

grandpaw

pgiraudin3 wrote:

Then the next thing to teach is why you choose to move either the aperture or shutter speed to the left or right. Aperture can control depth of field, and shutter speed can control motion...stop action or create an intentional blur. Photographing a waterfall with a fast shutter speed gives the illusion of ice...not necessarily what you want.

That is one of the main reasons that this handout is set up the way it is. I can easily show that if you move the F-stop to the right to get more depth of field you need to compensate moving one or more of the other two values to the left to maintain the same exposure. Same thing if you need to change shutter speed to stop or show action then you need to compensate one or more of the other two settings to maintain the same exposure. It makes it very easy to see what is needed.