ID 314113 - The Defocus node's Bokeh result at a low value looks like a rounded square

Problem summary
When using the Defocus node at low values, the shape of the Bokeh result appears to be a rounded square instead of a circle.

When compared to the ZDefocus node's Bokeh result at the same value, it is a much more circular.

Example:

Defocus 4

ZDefocus 4
​​

​

The Defocus does shape into a more circular shape at a higher size.

Customer reported version
nuke.10.0v6

Customer reported platform
centos6

Steps to reproduce

1) Copy the following and paste it in your Node Graph:

set cut_paste_input [stack 0]version 11.0 v2push $cut_paste_inputNoise { gain 1 center {1101 576} name Noise2 selected true xpos -982 ypos -51}ColorCorrect { highlights.gamma 0.2 highlights.gain 4 name ColorCorrect16 selected true xpos -982 ypos -16}set N2f63ae00 [stack 0]ZDefocus2 { legacy_resize_mode false show_legacy_resize_mode false name ZDefocus1 selected true xpos -901 ypos 40}push $N2f63ae00Defocus { defocus 4 name Defocus45 selected true xpos -1077 ypos 42}

2) Set your viewer 1 to the Defocus node and zoom in close

3) Set your viewer's second input to the ZDefocus

4) Switch between both viewer inputs to see the differences

Result: The Defocus node looks more 'Square' compared to the ZDefocus.

Workaround
Use the ZDefocus node for smaller sized focus levels.

Reproduced by support
Nuke11.0v2 - Windows 7 - Mac10.12 - CentOS6.9
Nuke11.0v1 - Windows 7
Nuke10.5v6 - Windows 7 - Mac10.12 - CentOS6.9
Nuke10.5v1 - Windows 7
Nuke10.0v6 - Windows 7 - Mac10.12 - CentOS6.9
Nuke10.0v1 - Windows 7
Nuke9.0v9 - Windows 7 - Mac10.12 - CentOS6.9
Nuke9.0v1 - Windows 7
Nuke8.0v7 - Windows 7 - Mac10.12 - CentOS6.9
Nuke7.0v10 - Windows 7 - Mac10.12 - CentOS6.9

Earliest version tested
Nuke7.0v10

Expected behaviour
The Defocus node Bokeh result should be more circular

Actual behaviour
The Defocus node Bokeh result looks like a rounded square