Aperture shutter speed and iso review

• F4  – looks the best at  1/125sec of a second shutter speed. Background is very blurry
• F5.6 – looks the best at 1/60sec of a second shutter speed. Background is really blurry
• F8  – looks the best at 1/60sec of a second shutter speed. Background is a little blurry 
• F11  – looks the best at 1/60sec of a second shutter speed.Background is barley visible
• F16  – looks the best at 1/30sec of a second shutter speed. Background is visible but not clear
• F22  – looks the best at 1/30sec of a second shutter speed Background is visible

Questions.

1.)At a slow shutter speed the picture becomes darker.

2.)The photographer should find some better lighting 

3.)If there is a tree in the background i want to tell that it is a tree but dont want to see the leaves