Learning to see and use light is one of the hardest and most important parts of photography. The other day I was taking some snapshots of the grandkids while they were playing. I decided to experiment with light and using available light (truth be told I was too lazy to go find my external flash or setup my studio light)
This 1st shot I took of them from where I was sitting but since they had a bright window behind them they are just shadows.
This is way too dark so I turned on my camera flash, I have the light now but I didn’t like the way it looked, notice the harsh shadows.
I turned the flash off and turned my ISO up to 800 and made sure my focus points were only on the kids and not the window, the light turned out much better but of course the kids decided they wanted to move so the focus is off (using a 3 year old and 6 month old as a practice model is a little difficult) A higher ISO will give you more grain and not as clear focus, also since I am using only the available light in the room it gives me a slower shutter speed which does not work very well with active kids.
Now another problem with using light from the window behind them is that their eyes are not very bright and you can barely see the color in them, a quick easy fix for this is to get a piece of white poster board and hold it in front of the child so the light bounces back into their face.
Now you can see the color of her eyes, but our focus is still not very good.
To get the best use of window light is to turn the kids around and have them face the window so the light is directly on their face instead of their back. In this photo my granddaughter is sitting facing the window so there is lots of nice light on her face and I used the white poster board to bounce some more light into her eyes so they look really bright, since I had lots of light I was able to lower the ISO and I have a nice clear focus image.
The best way to learn about light is to experiment, take photos in different light sources and different angles until you are use to seeing how light affects your photos and how you can add more light to get the look you want.