What is your depth of field (DOF) preview button for? Answered here!

Posted on October 6, 2007 | 4 Comments

I have had this question asked to me many times and it has been on my list of things to talk about for quite some time. There are a great deal of Digital SLR (DSLR) photographers out there who have probably never used it, or even havn’t even noticed it!

Depth of field buttonBasically, the depth of field (DOF) preview button is for visually checking how much depth of field you have in the photo (I have a depth of field tutorial here if you are unsure). If you in aperture priority mode, because you want to use a certain aperture – an example might be that you are taking a photo of something and want to try and get a certain part in focus and another out of focus (OOF) – so most people would snap off a couple of shots like this and look at the results of the photo on the display screen to see whether the shot worked out. There is a much easier way to do this, by pressing the depth of field preview button and looking through the viewfinder you can see exactly what will be in focus and what will be blurry. It will look a little darker but hold on, we’ll get to that!

Why when I press the DOF preview button and I look through viewfinder does everything go dark?

When the DOF preview button is not pressed the aperture will stay as wide as the lens will allow, so if you click the button nothing will happen. As soon as you stop down (make the aperture smaller) the ‘eye’ gets smaller to restrict the light entering, so if you set your camera to Av (Aperture priority) mode and select f/11 and NOW press the DOF preview button, you can see that it darkens and you can actually hear the noise of the aperture getting smaller. If you have another look in the viewfinder (although a little dark) you can see EXACTLY the DOF that will be in the final picture!

So in summary:

The DOF preview button is simply to view the ACTUAL depth of field that will be in the final photo – BEFORE you take it -based on the size of the aperture that you have set. When you hold the button, the camera physically adjusts the apeture into exactly the right size as you asked it.

Go and test it, set your camera to Av (Aperture Priority mode), choose a F stop such as f/11 and walk around your house looking through the viewfinder and pressing the button!

Related posts:

  1. RAW vs JPG – A brief guide – Which one is good for you?
  2. Tethered shooting with Lightroom and Canon 40D
  3. What is camera ISO?, SLR Digital and film ISO explained
  4. Simple guide to shutter speed
  5. What is SRAW file format?

Follow Chris Ridley by RSS Reader

You might also like:



4 Responses to “What is your depth of field (DOF) preview button for? Answered here!”

  1. Sylvia Wee
    December 23rd, 2008 @ 3:56 pm

    Thanks for this….This is the thing that I couldnt get right :0 when I choose Aperture Priority.

  2. carolb
    February 3rd, 2011 @ 6:02 am

    thanks!

  3. Scotty
    July 26th, 2011 @ 4:38 pm

    My girl friend is a “photographer” and I always ask her what she is doing when she plays around with the setting on her camera. Your blogs have helped me understand a lot better as to what goes on. In fact I think she needs a couple more pointers her self. Thank you so much for these insights and helping me not look like an idiot. lol

  4. Chris Ridley
    July 27th, 2011 @ 7:44 pm

    I’m glad it’s useful – thanks for stopping by, much appreciated!

Leave a Reply





This post appears in: All Photography Blog Posts, Techniques & How To
Tags: - - -

  • buy photography magazines and digital magazine subscriptions
Recent Stories: Cambodia

An awesome adventure temple hunting in Cambodia, stunning location & beautiful people.
View this story »

Cambodia Stock Photography
Find me
About Chris

I'm passionate about photography, a true obsession that seems to embolden as the years pass. I'm entirely self taught through reading, experimenting and just old fashioned practise for hours....
Read more »