Exercise: Focus at different apertures

f/4,2 1/25" ISO 200

27 mm focal length 

Nikon d90 with Nikkor 18.0-55.0 mm f3,5-5,6 lens 

f/8 1/8" ISO 200

26 mm focal length 

Nikon d90 with Nikkor 18.0-55.0 mm f3,5-5,6 lens

f/11 1/4" ISO 200

26 mm focal length 

Nikon d90 with Nikkor 18.0-55.0 mm f3,5-5,6 lens

f/29 1,30 sec. ISO 200

26 mm focal length 

Nikon d90 with Nikkor 18.0-55.0 mm f3,5-5,6 lens

For this exercise, I’ve put three different candles on a table. One of them is very close to the camera, while the other two are in the back part of the image. I’ve set my camera in aperture priority mode and made several pictures, starting from the biggest aperture (f/4,2) and finishing with a smaller one (f/29).

In the picture taken with the biggest aperture, we can see that the sharpen area is reduced only to the closest area. The foreground candle is sharpen but the rest of the images is very blurry/out of focus. The conclussion is that, the smaller the aperture is the sharper and deeper the picture will be. In this case, I needed a f/29 aperture so that everything in the scene is in focus.

As I changed the aperture, I also needed to change the shutter speed to get the same exposure, but in this case my camera made the changes by itself because I set it in aperture priority mode, which means that for whichever aperture I choose the camera metering will select the correct shutter speed.