Quick formula for estimating DOF?

[Luke Nolan]

I've had my 50D for awhile and have had some amazing results so far. I have a 50mm f/1.8 II which is awesome for the price, hope to get a 1.4 soon. I've been taking lots of portraits of my son and love the background blur. I've also had some shots ruined by not stopping down when I should have for group shots. Obviously with a fixed focal length and similar aperture the DOF is also affected by distance to subject.


Is there a quick metal formula for estimating DOF? Like, at 50mm and f/1.8 with the subject 48 inches from the camera DOF will equal x inches but at 20 feet from the camera DOF will equal y inches. Are there any other good tricks for knowing how wide open is too much?

[btaylor]

I don't think there's an easy way to be honest (unless you're a mathematician). I've got the DOF Master application on my iphone that gets pulled out occasionally but apart from that I don't know of another way.

[jcrowe87]

A lot of people used to carry around charts for primes, though since zooms are so popular now it is a little tougher to cover all the bases. I also have a DoF app on my phone, it works wonders and is always with me, taking care of all the calculations I would ever need.

[neuroanatomist]

Are there any other good tricks for knowing how wide open is too much?

Don't forget about the simple physical method that's already a feature of your camera - the DOF Preview button.

[iND]

This is an area that I have been working on for some time.


I know the preview is acceptable but I want to plan my shots and have a working idea of DOF in the preshot process.


My suggestion is that since it IS A CALCULATION


Why can canon not build it into the menu screen and have it read out next to aperture, speed, iso, lens focal lenght.


It really is doable.


I also looked for a pocket chart that I could carry.


This is what I have found is the best solution:


There are several online depth of field calculators that you can use to make your own pocket charts for dof.


The site I use is:


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


good luck