Manual Tutorial #3 ~ ISO

I can be honest with you, right?  I'm about to admit something completely embarrassing and you have every right to laugh at me.  Back in the film days, I always thought the number on the film was how good the film was.  Perhaps it was because a higher ISO film always cost more, so I just assumed it was "better"?!?  I would purposefully choose film that was 400 or 800 and then wonder why my photos were grainy.  Granted if I were shooting indoors, that would have been a good choice.  But the majority of my photos were taken outdoors on bright sunny days... yeah, totally not necessary to have that high of an ISO.

ISO is not a higher quality of film, but rather how sensitive the film (or digital sensor) is to light.  In the film days you were limited to choosing one ISO number for your entire roll of film.  Now with DSLR's we have the option to change our ISO at our whim and desire.  ISO has gone from a thorn in my side to being my best friend.  It is the easiest of the three components of exposure to understand, but it is also the most important (in my opinion).  When you fully embrace and understand ISO your creative opportunities will open up.

The higher the ISO number, the higher the sensitivity to light.  Think about being in a dark room with one small light on.  If you wanted to capture anything in your photo other than a black room, you will need to have a high ISO number.  By putting up your ISO, your camera is more sensitive to light and you will be able to see more in the photograph.

The lower the ISO number, the lower the sensitivity to light.  Think about being walking outdoors on a really sunny day, WITHOUT sunglasses ~ yeah...  You are going to squint your eyes so tightly, they may as well be shut completely.  This is the same thing with ISO... You would want a lower ISO number (100 or 200 usually).  This makes your camera less sensitive to light.

Sounds good, right?  Well, here is the catch... Yes when you raise up that ISO you are able to see much more in the photograph, but that means more digital "noise" or "grain" in your photos.  There are ways to process some of it out through computer software ~ but often times it is just the price you pay.

Comparison of Different ISO Settings

Look at the comparison of these three photos.  Can you see the grain (noise) in the yellow background?   How about the black of the police officer's uniform?  In the first photo it is solid black but by the time you get to the last photo it is pixelated and spotty.  Do you see any other differences between the photos?

I am going to take this a step further and give a few different examples.  Lets look at the chart I used in Tutorial #2 again.

All three componenets of exposure intersect and affect each other.  When you change one, you have to also adjust the other parts in order to have a perfectly exposed photograph.  One of the reasons why you would adjust the ISO is to have a higher shutter speed.  For example, say you are taking a photograph of your child indoors.  If you were going to have a perfectly exposed photograph, that would put your shutter speed lower than you can handhold it (remember 1/60th of a second is the lowest you want to handhold it ~ any lower and you really need to have it on a tripod.)  In order to take this photo without pulling out the tripod, you decide to raise your ISO.  By raising your ISO, you are able to also raise your shutter speed.  Problem solved.

A general rule of thumb is that you really don't want to have your ISO higher than 400.  Any higher than that and you will begin to see noise in your photos.  But you can make that decision in the moment as to what is more important.  Sometimes there is just not enough time to pull the tripod out.  Or you have the time to pull out the tripod, but your "subject" won't stay still... causing blur in your photos.  By raising your ISO you are able to have a shutter speed high enough to freeze the action.

Homework for Tutorial 3:

1) If you haven't already done this, locate where ISO is on your camera and how to change it.  Pull out your owner's manual and get comfortable with it. 

2) Put your camera in "P" mode.  This will figure out all your settings for you, but you can adjust the ISO and a few other things.  Don't get comfortable here (remember our goal is to be in Manual Mode), this is just for now...  Put your ISO to 100 and see what settings your camera says.  Write them down.  Then change your ISO to 400.  Look at your settings again and write those down as well.  Look at how they compare.  Go ahead and write your settings in the comments below along with any other observations you may have.

I hope this is starting to make a little sense, but if it isn't don't worry, you are not alone!  If you have any questions at all, PLEASE comment, email, message me.  I am here to walk you through this and help you understand these concepts in any way that I can!

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Continue forward to Shutter Speed

Capturing the Moment,

Corrie <3

Link to Manual Tutorial #1
Link to Manual Tutorial #2