Nuke Photography Effects

I have lately been interested in trying to learn more about different effects to add to CG composites in Nuke to give them more real world properties.
I rendered all these images in Arnold, using a HDRi and key light, then took that into Nuke, and did a rebuild of the passes to get the beauty. The background was added on using the HDRi mapped onto a sphere in a 3D scene.

One thing I was interested in trying was different filters on the ZDefocus node, this can give a little more interesting bokeh, that of you would find with using different physical camera lenses. Here is a short article about it.

This is the basic ZDefocus node blur, with no changes to the filter:


Different camera lenses can produce differently shaped bokeh, due to the number of aperture blades within the lens, for example, 3 blades produces triangle blurred highlights:


or 4 blades produces squares:


The ZDefocus node has 3 filters; disc, which is most basic, bladed, which gives more control over the characteristics of the blur, and image, where images or nodes can be plugged in for even more control over shape and colour.

Here using the filter pipe I have added slight chromatic aberration to the blur:


This gives each bokeh ball a slight red and green highlight on the edges, best seen near the dragons mouth. 
This is the filter I used to get that effect, created in Nuke:


Lenses can produce a wide range of little properties, such as the Helios 44-2. Some produce bokeh balls which appear to have a highlight around them, like below:


Here I have re-created that effect in Nuke:


using this filter image:


And here's how that plugs into the node tree:


I created the filter using a roto node, any shaped can be used but I wanted to stick to circles for this. The circle shape is copied, scaled down, graded darker, blurred and merged back on top of the original shape. 
This particular effect can also be achieved just using the bladed filter type. 

I really like shooting photos with vintage lenses because of the properties like this, they give a really unique feel, so I would love to transfer that into my CG work. Even using the ZDefocus node and setting a real world aperture value, such as 9 which is a somewhat standard in professional lenses, would give a nicer effect than a simple blur.

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