Your Challenge was to take two photos of your favourite subject (fluffy toy?) at different ISO settings.
Say hello to Bunnie!
The two photos were shot at ISO 100 and ISO 6400. Can you see the difference? Can you tell which one is ISO 6400?
Let's look at a close up crop portion of each photo.
Notice that in the ISO 6400 image, the background in particular is grainy, the colours are a bit dull and the whole picture is less contrasty. It lacks crispness and "pop", for want of a better word.
High ISO is not necessarily evil, but be aware of the effects.
In the ISO 100 image Bunnie! seem to stand out more. There is another problem though. Because the the amount of light the sensor can absorb was low, and it was a dark, overcast day, I had to lower my Shutter Speed. We will discuss Shutter Speed in a couple of weeks, but you already know that the longer the shutter remains open, the higher the likelihood of camera shake. Dear Bunnie! is a bit blurry in the ISO 100 image because I wasn't holding the camera still enough.
The lowest ISO, even though it gives the richest image quality, isn't always the best choice either. Most of the time we are probably using something between ISO 400 and ISO 1600.
Could you, at a glance, tell which photo was shot at ISO 6400? What is the upper limit ISO setting on your camera? Tell me your answers in the Comments below, or send me a personal message on the Contact page.