Lets give the word to zy0rg, the creator of post_depth plugin:

That variation is used to create the depth blur effects in 3d fractals.
Unlike Apo's native depth blur, with this plugin you can use any variation (I'd recommend sineblur) for blurring.
The drawback compared to native blur is that you need to place the blurred object "manually" (i.e. using ztranslate, rotate_x and rotate_y) so it might be a bit tricky to use. But I think that the result is 99.98% worth it.

You can download post_depth (and a few cool blurs) here:



A few examples of post_depth results:

Basic Usage

To use post_depth, you will need parameters without a final transform. As an example, I will use this lovely work by SuicideBySafetyPin:



For best results, you need to first set to 0 all the Apo default 3d settings: Depth Blur, Pitch, Yaw, Height. Your Adjustment window should look like this:



Now, in the editor, add a final transform. Remove linear, and set post_depth to 1. Add some sineblur (0.01 - 0.1 should be good).
Then, use pre_rotate_x, pre_rotate_y and pre_ztranslate to rotate and move your flame to give it a 3d look again.
If the flame is entirely blurred, try changing pre_ztranslate values.



The result should look similar to this (I changed the resolution to fit the journal better):



To add bokeh, add a transform and remove linear (try adding some pre/post_rotate_x, pre/post_rotate_y, pre_ztranslate and ztranslate to it, nothing else). Tweak the weight of this transform until you get the bokeh strength the way you want it.
Here are the parameters for my tweak (extra bokeh version): Post Depth Example 1

Advanced Usage

Reminding, to use post_depth you need a "free" final transform. So what if your parameters already have a FX and it cannot be removed? This can happen, for example, when creating blooms. Lets take a look at those parameters by C-91:
You may want to use Apo 7x15a or b to tweak those.



First, go through the parameters and note down the transforms with:

• opacity different from 0 (visible transforms)
  
• blur as main element (blurry transforms)
  

In the parameters for the bloom above, all the transform have non 0 opacities, and only transform 1 is blurry.

Set the opacity of all transforms to 0. Your preview should display plain background after you`re finished (left picture).

Add a new transform. Set its Color Speed to 1.
On the Xaos tab, set all "to" values to 0, except the ones to the blurry transforms, which should remain 1 (right picture).
Also, set all "from" to 0, except the ones from the visible transforms (transforms 1-4 in this example).



Next, go to the blurry transforms - only transform 1 in this example, and set all "from" Xaos values to 0, except the one from the last transform.
This will keep your render a bit cleaner.

Finally, time to move the FX. On the last transform, remove linear, and copy all the final transform setup:

• Same variations in identical amounts to ones used on the FX
• All variables used set to same values
• On transform tab, all 12 values (both transform and post transform) should be set to same values as ones on the FX

Once youre finished, just remove the final transform. Your fractal should look identical to the version with final transform.



Here, the params for my tweak: Post Depth Example 2
Now just add some fancy post_depth to it . Also, keep in mind that you may need some extra brightness after those changes.



Also, if you plan using post_depth in your work, consider using the technique described above directly. When creating your fractal, instead of adding a final transform, add a new transform with described Xaos setup, and use it as final transform straight ahead

A Notepad Shortcut

To copy your FX setup, you can also use a small notepad hack. This may look scary at first, but is really handy when you have a final transform with 5-6 variations and 20 variables. And way faster than inputting everything manually
Copy your parameters from Apo and paste them into notepad, and then locate the following part (look for finalxform):

   <xform weight="0.5" color="0" symmetry="1" linear3D="1" coefs="1 0 0 1 0 0" chaos="1 0 0 0 0 " opacity="1" />
   <finalxform color="0" symmetry="1" zscale="0.156" zcone="-1E-005" julia3D="2" pre_circlecrop="1" coefs="1 0 0 1 0 0" julia3D_power="-3" pre_circlecrop_radius="40000" pre_circlecrop_x="0" pre_circlecrop_y="0" pre_circlecrop_scatter_area="0" pre_circlecrop_zero="1" />
   <palette count="256" format="RGB">
      100F092626194A402A663B277C4F28885B2CA05E38AD5048
      B65046D24D47D15243CA3026E35836D36636E27F32EA8F38

This is the code for your last transform and your final xform. Now, replace the underlined part with the bold part, and erase everything from "<finalxform" to "/>".
The bold part should have the following elements:

• all variations used (zscale, zcone, julia3D, pre_circlecrop)\
• all their variables (such as pre_circlecrop_radius and julia3D_power)
• coefs

The copy and paste corresponds to copying all variations, variables and transform setups. Erasing the "<finalxform ... />" element is same as removing the final xform in the editor.
You should end up with this this:

   <xform weight="0.5" color="0" symmetry="1" zscale="0.156" zcone="-1E-005" julia3D="2" pre_circlecrop="1" coefs="1 0 0 1 0 0" julia3D_power="-3" pre_circlecrop_radius="40000" pre_circlecrop_x="0" pre_circlecrop_y="0" pre_circlecrop_scatter_area="0" pre_circlecrop_zero="1" chaos="1 0 0 0 0 " opacity="1" />
   <palette count="256" format="RGB">
      100F092626194A402A663B277C4F28885B2CA05E38AD5048
      B65046D24D47D15243CA3026E35836D36636E27F32EA8F38

Now just paste the resulting params into Apo.