Acacia was conceived as a tool for the 1st AC and 2nd AC.  "Acacia" has not one, but two ACs in it. :)

The most common problem is that you are not configured to use a motion-picture or digital video camera.  The type of camera selected is important, and affects what options are available!

Go to the Equip screen, and tap Manage under the Camera section to add a new camera, or edit an existing one.  Make sure that under "Camera Type", you have selected either Film Cine, Digital Video, or Analog Video.

As of the 0.8.0 release, the slate also requires that you have configured a Lens, Medium and Project.

This seems to be a sticking point for a lot of users.  Acacia may eventually have a facility to do this, possibly through some sort of web interface, but it's not high priority right now.  

The key point here is "other DOF calculators" - Acacia aspires to be far more than that. To provide camera defaults in most apps, all you do is list all the cameras you can think of with a particular sized sensor, and lump them all together.  Easy.  Acacia, on the other hand, provides facilities for logging shots, specifying frame rates and managing media and so forth..  That means that each camera has to be entered with all its parameters. That's a lot of research and error-prone data entry.  I'm not really inclined to do that for an app that I give away for free.

Lenses are even more problematic - there are thousands of models out there, and Acacia provides facilities to make the Optics screen layout roughly represent the equipment you actually use - so minimum focus distance, focal length range and markings and aperture range would all need to be diligently entered, checked and rechecked.  Then someone would still complain that his favorite lens - a Soviet-era 35mm lens that was remounted to PL-mount - was missing.

Furthermore, for shot logging, the idea is to log the exact equipment (perhaps by serial number) for reference.  This may be useful in identifying faulty equipment when reviewing dailies.

They're not!  These are actually the correct numerical values, given by 2^n/2.  Since Acacia displays aperture as a decimal value, it seems to make sense to actually display the correct value.  As a consolation, I made the F-stop spinners display the conventional label, with edit boxes to supply precise custom values.

In the future, there may be an option to display aperture as standard F-stops, plus a fraction  (i.e. 22 +1/3).  Or maybe there won't be.  I have no idea.

Most of these problems appear to be related to the change in database layout in 0.7.0.  While I'm trying to address these properly, the fastest way to get a working installation again is to uninstall, then re-install.  This does, however, have the undesirable effect of losing all your saves cameras, lenses and shot data.

Acacia gets its viewing angle data from your device's camera from the camera itself.  Since I'm not sure if this feature is supported by all devices or how accurate it is, you can manual configure this yourself.

There might be wizard-thingy to help you with this at some point, but in the meantime, you can be your own Wizard of trigonometry:

A paid version has been released, but there will always be a fully-functional version with no ads.   One of the features I'm considering would be web integration, which may be offered on some sort of paid model.

The free and so-called "beer-fund" versions are functionally identical, and you're welcome to use either.  If you find it useful, and would like me to continue adding features (and boy, is there a long list right now!), buying me a beer would be welcome encouragement.

The only real material advantage of buying Acacia would be that new releases will first go out to the free version.  Once deemed stable, the Beer Fund version will follow within a few days. This should help the Beer Fund users avoid the occasionally broken releases.