Fixed Portrait Shoot

ISO: 100

Aperture: 5.0

Shutter Speed: 1/100

ISO:400

Aperture: 3.2

Shutter Speed: 1/8

 ISO:800
Aperture: 6.0
Shutter Speed:1/00

 ISO: 1600
Aperture: 5.0
Shutter Speed: 1/00

 ISO:3200
Aperture: 5.6
Shutter Speed: 1/30

1. The best ISO setting for my portraits was 100.
2. My best picture would have to be my first one because its clear and you can see the model even though its dark.
3. Yes I was able to create equivalent exposure by changing the aperture and shutter speed.
4. When the ISO's are different I can still take a clear picture by changing aperture and shutter speed.