DoF calculations

Joined: 18 Feb 2005 Posts: 60 Location: Arlington, VA

Hi all,

Does anyone have a good back-of-the-envelope way to calculate depth of field for given f/stop, distrance from subject and focal length?

I've been running into portrait situations where my DoF is too shallow, but that only shows up when looking at the full picture.

Thanks all,
-Dave

Posted: Sun Nov 05, 2006 8:29 pm

My lenses all have a depth of field scale on the focusing ring.

You can print out a depth of field calculator from the Internet. Google: Depth of field Calculator. You will find several.

If you make a note on the print what f/stop and focal length you used you will quickly learn what to expect and you will not need the calculator any more.

Joined: 18 Feb 2005 Posts: 60 Location: Arlington, VA

Packard -- thanks. I will look for one online that prints out... have found lots that will calculate on the fly but haven't yet run across a printing one.

The lens that I specifically have in mind is the 50mm f/1.8 Mk II -- no scale on it.

best,
-Dave

Joined: 09 Sep 2006 Posts: 114 Location: Boston, MA

aside from what Packard said..do you use your DOF preview feature on your camera? Since 1.8 is a very large aperature, if you are shooting at anything about it your DOF is going to increase..also....and this will help because its all I use now..

no matter what lens, no matter what aperature, no matter what format..optical physics says that you will have 1/3 of your DOF in front of the point of focus and 2/3 of your DOF behind the point of focus.. so depending on your focal length, and how physically close to the subject you are you can gauge what you are going to have sharp and what you are going to have soft.. wide angle lenses give you a greater area of sharp focus at wider aperatures than do telephotos and the farther away from a subject you are the great your DOF will be...

Use the preview, I know the viewfinder gets dark, just let your eyes adjust.
If its something I have to do everyday as a pro, then I feel its worth the time to tell everyone else to do it too.

Posted: Wed Nov 08, 2006 9:09 am

Print from this site. Set the format and the focal length first.

http://www.dofmaster.com/doftable.html