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ISO explained

ISO explained

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This is a continuation from a week ago when I wrote about Aperture.  Today I will explain in the best terms that I know what the ISO is and means.  You will find very quickly that if you change one setting (say the aperture) then you will probably need to change the other settings too (ISO and shutter speed).  I sort of like to think of them as a triangle.

(to find out how to control your specific cameras ISO setting… please refer to your cameras owners manual)

Today I will talk about ISO:  Sensitivity to light.  In the days of film cameras the ISO numbers were in relation to film.  You could by different film speeds that would give you different results for each one.  If you remember the days of film- if you were to roll that film out of the roll what would happen?  The film would absorb up the light and the film turned a whitish color (meaning that you just ruined your film!)!  The ISO numbers were to show how quickly this would happen.  So if you had an ISO sensitivity of 100 the film would absorb it slower than one with an ISO of 800 or more.

In digital photography, there is obviously no film, so what does ISO mean?  Pretty much the same thing, but instead of working with film we are working with an image sensor.  The numbers are in the same order …the lower the number- the less sensitive.  The higher the number- the more sensitive.


So how do you know what setting to place the ISO on?

As a general rule of thumb… the lower numbers are best.  I like to try and stick to 100 to about 400.  In low light situations I sometimes bump it up to 800-1600.  Most cameras- even digital SLR’s do better below 1600.  Above 800 you are likely to get lots of noise (sometimes called grain) in the pic.  Sometimes noise is a good thing in very artistic or moody photos.  Imagine a party with candles and people waiting for the birthday boy or girl ready to blow them out.  A high ISO might actually set the mood here.  Most likely you will want it set to the lowest possible to get the clearest images possible.

In broad daylight with the sun lighting up everything in your view: stick to an ISO of 100.

example:  these eggs were right in the sunlight.

In the shade with a little sun shining through you can bump this up to 200-400.

example: the girls were sitting under an awning.  I had some light coming through, but not enough to get a good exposure without bumping up the ISO to 400.  This ensured that my sensor was absorbing every bit of light that was available.

These next two images were taken in a low light setting, but I set the ISO from the lowest to the highest to show the difference in the film grain/ noise.   The ISO on the pic to the left was set to 500  the pic on the right was set to the highest the ISO would go… 25600!!!   Notice the image on the left looks slightly burred.  That is because when you set the ISO lower (less sensitivity)- there needs to be more light coming in.  To make that happen you can change the aperture or the shutter speed.  Since I wanted to have a good depth of field (see my aperture post)…  I had to change the shutter speed in correlation to the ISO.  Shutter speed is the easiest to understand in my opinion and I will explain that in detail in the next photography tutorial.  For now, just think of it like this: The shutter speed determines how fast or slow the aperture stays open.  So obviously at my low shutter speed there was more light being let in, but the tiny movement of my hands blurred the picture a bit since the aperture was open longer.

 Clear as mud right?  LOL  If you are new to all of this the best thing that I can suggest is to go out and play with your camera!   For our aperture lesson I had you use the Aperture Priority setting on your camera.  Now you can start trying out the “m word” MANUAL setting.  Just remember that you are working in a triangle.  One setting will affect the rest.  Next week I will dig deeper into the shutter and what it can do for your photos!   I promise that it gets easier as you practice!!

 So what have you been up to this week?  Share all of your great ideas here.  I love getting to see your work every week!!!

Remember to make this fun for all:

1. comment on at least 2 other projects that are linked up

2. grab one of my buttons to put on your post or on your blog somewhere (A text link is ok too)

3. Become a follower of BNC

Thanks and I hope you enjoy the party!!!

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