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Aperture – What is in focus?

© Joe Randeen :: 3 Penguins Photography
F 2.2 – 1/4000 – ISO 500 | © Joe Randeen :: 3 Penguins Photography

When I teach photography, one of the common questions is that of aperture. It’s a part of a larger subject – exposure. Exposure is the relationship of aperture, shutter speed and ISO. We are not going to tackle that in this short post.

The other day I was shooting an event. I saw these 3 sisters and asked them to gather together. If you notice, they are staggered from front to back. I opened up my aperture to f 2.2, which is relatively wide. As such the only thing that will be in focus is what I focused on and anything on that same plane.

I focused in on the sister in the center, resulting that they other two sisters are out of focus. I did this on purpose, for effect. I had plenty of light (speed was 1/4000), so I could have closed my aperture down to 8 or more and had all three girls in focus.

Depth of Field

So, what this photograph illustrates is that the larger the aperture the smaller the focus depth.

If you’re taking pictures of more than one person, you’ll have to either have both people on the same plane or reduce your aperture size.

Hope this helps.

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