In the beginning, the lens created the depth of field… or, if you are a “creationist”, perhaps the depth of field created the lens. 
For people who haven’t read my book on Stereoscopic Religion, let’s look at two 17mm lenses, spaced *about* 63mm apart, give or take a few mm’s. This ain’t rocket science, peeps.
Yes, you’ll probably need a beamsplitter to get them that close together. Or if you’d like, just throw away the camera(s) and use your real eyeballs… same-o, same-o. 
Let’s go with a .0333 Circle of Confusion. Sound familiar? The “333′s” again. OMGawd!
Please trust me on this one and use f/5.6.
You can start with a near point at .22m and a far point at .29m.
You should have 1.2mm of 36mm or 3.33% (yes, 1/30) “max gap”, not coincidentally a stereo calculator default. There are no coincidences. I will assume you are using a standard 35mm camera equivalent in the landscape mode. LOL.
Rocket scientists who are doing this with their eyes should measure the distance between their pupils and see if it is exactly 6.43cm. Please measure your interaxial (stereo base). It should be exactly 6.43cm. The rest of us can just “get close” to 63mm and live happily ever after.
Now change your near point to .39m and your far point to .70m. Rocket scientists can change their interocular/interaxial/stereo base to exactly 6.21cm.
Speeding up, now, so pay attention…
Also do:
Near point: .52m
Far point: 1.32m
Stereo base: 6.06cm
f-stop (always for this experiment) at f/5.6
then:
Near point: .63m
Far point: 2.37m
Stereo base: 6.06cm
Lastly:
Near point: .80m
Far point: 11.6m
Stereo base: 6.07
Welcome to Infinity
Any near point farther than .92m, you can just use “Infinity” for your far point.
This actually defines “optimum depth” around this neck of the woods…
everything in clear focus. No “limited depth of field”.
3.33% Max Gap.
We have close to a 100deg stereo hFOV… more like 96deg or something, but that’s not a big deal… just use something close to 100 deg.
100 deg / 30 = 3.33 deg.
OMGawd! Another coincidence?
No way, dude.
Thanks,
Roger Maddy
Blog: http://rogermaddy.com/
Twitter: http://twitter.com/rogermaddy