31+ Days Of Photography Experiments – Depth Of Field – Changing Focus Points

Yesterday’s Topic: Depth Of Field – Changing Aperture

Let’s try a little Jedi training with you tonight. I’m not going to give you any supporting images to help you see what might happen.

“LUKE: (laughing) With the blast shield down, I can’t even see. How am I supposed to fight?

BEN: Your eyes can deceive you. Don’t trust them.”

Actually, Old Ben had it wrong, I want you to trust your eyes.

Oh, this is post 3 in the 31+ Days Of Photography Experiments. Catch others like it here.

Now then, yesterday you learned to change the depth of field in a shot using the Aperture. Today let’s see what happens when you change the focus point in a scene.

Here’s the experiment you can run:

1) Scene setup: You will need a long, flat surface, like a wall or a floor (if you want to get down on it). A table or counter will work as well.

2) Place a yard stick along the table or wall. Yeah, I know, the chances of actually owning a yardstick are slim. So set up an object every foot along the table for a total of six feet. Taper them slightly so you can see them all at once, much like you did yesterday.

3) Switch your camera to Aperture Priority. Choose ISO 400 and pick the smallest numbered aperture you can (e.g. f/4, f/1.8).

4) Switch your camera to select only the middle focus point. There are dozens of ways to accomplish this depending on your camera so I suggest you consult your manual to learn how to pick just one focus point and keep control of it. If you really can’t find it after reading for 15 minutes, leave a comment and I’ll help you.

5) Zoom in to 50mm or as close as you can get to that focal length. If you are using a point and shoot, zoom in half way from the nearest to the farthest zooms.

6) Focus on the first object and get as close as you can before your camera won’t focus any more. This will be somewhere around 1-2’/.3-.6m.

7) Make sure you can see all the objects on the table/floor/counter. You can use a wall that has some type of pattern on it. If you have no patterns, give your kids some crayons and tell them to go to town on the wall. Instant, random patterns.

Let’s just review where you’re at as we’re doing this all Obi-Wan style. Stuff spaced out at one foot/.3m increments on a table/counter/floor or some type of pattern on a wall. You have control of your Aperture and ISO and you will let your camera take control of shutter speed. You selected the smallest numbered aperture you can, likely f/3.5 or f/4, but maybe less. It’s not too important right now. Oh yeah, make sure there is decent lighting. And chocolate. It’ll help, trust me.

8) Take a photo while focused on that first object.

9) Focus on the second object. Do not move your camera front to back or too far left and right. Panning to the side (as if your camera is on a swivel) is best. Baby steps.

10) Take a photo.

11) Focus on object #3 as above and take a photo.

12) Continue this until you have shot all objects in turn.

Done! With the shooting.

Now review the images on your computer. Run through them one by one and look to see how many objects are in focus in each picture.

Remember, you changed nothing in between the photos as far as your camera goes except the point of focus. So how many objects were in focus when you focused on the first object and how many were in focus on #4?

I’m not going to give the answer to this one tonight, maybe tomorrow. I’m waiting for you to have your “LUKE: You know, I did feel something. I could almost see the remote.” moment.

What? Too many Star Wars references?

Tomorrow we will build on the Depth Of Field concept by changing distance and zoom.

31+ Days Of Photography Experiments is a series written by professional photographer Peter West Carey on The Carey Adventures.Com. The series is designed to unravel the mysteries of photography so you can take better pictures through practical experiments on the material found in 31+ Days To Better Photography. Subscribe here to receive all the updates and bonus material. Your comments are always welcome.

6 Replies to “31+ Days Of Photography Experiments – Depth Of Field – Changing Focus Points”

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      • Dave McCorquodale

        Hey Peter,
        That experiment stumped me 🙂
        I tried to keep all the items in the same frame and moved from one to the next, but to do that i had to stand at least 6/8 feet away? Was that correct?
        I also tried to stand within 2 feet as close i could get and still focus on one item then pivot to the next, refocus and shoot etc.,but obviously not keeping all the stuff in the frame.
        What was i doing wrong? thanks, Dave

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