Depth of Field (DoF) and Hyperfocal Distance

12th September 2015
I was talking to a friend today, and we got chatting about Hyperfocal Distance... and I thought... good Blog ... so here I am.

Anyone that's into photography will understand the concept of Depth of Field (here on in called DoF to save me typing a lot).
Where what you have in focus (sharp) in your photo is controlled by a couple of factors - mainly your aperture setting.
Still using Fully Auto or "P" mode ? Don't get off there and onto Av - Aperture Priority.
Good.

Right, well if you're shooting a photo of a friend, and you want them to stand out against the background... you want the background blurry. So set an aperture that is wide open like F2.8 (yeah I know, some lenses only go as wide as F5.6 etc so go as wide as you can.
Another way of getting a smaller depth of field is to zoom in.

If you zoom in on a subject the same aperture will render less in focus (smaller DoF) , zoom out to wide angle... you'll get more IN focus (larger DoF).

One thing to always remember... when you focus on something with your camera, almost all of the time there will be a short range before your focus point that will be sharp, and a larger area beyond your subject that will be sharp.
This is the DoF you have to work with. You can completely forget about it most of the time, but just keep it in mind.
It will look something like this crude photo with Post-It-Notes I made on a ruler...




So let's say you're out at night and you want a photo of a local landmark with the starts and moon in focus too. You might be stuck with a wide aperture so you're struggling to get everything in focus.
But if you look again at the crude photo of my ruler and post its... there's really a bit of wasted space in front of the subject.
Here's what I mean with another crude drawing of a bridge, and the far away moon. And you're focusing on the bridge...



As you can see, the moon & start will be out of the focus range and soft and blurry ... BOOOO !

But if you use the Hyperfocal distance, or at least the principle about it you CAN get everything you need. You focus BEYOND the bridge (there will be an exact distance to give pure Hyperfocal distance) and bingo! Everything is sharp that you want.



So there you go. An easy way to understand Hyperfocal Distance and DoF.

There are loads of good Apps for smartphones that show the exact details for each lens length, camera body, focus range, aperture etc.
I use DoF Calc and Photocalc.



If you found this useful, please leave a comment below, and if you'd like to ask a question about anything else photography... again , ask away !


G.x

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