Physical Defocus

Hello folks…

Just tagging an issue with PD (physical defocus). The node is almost excellent! Works well with cgi passes in creating DOF with nice custom bokeh, all jolly good!! EXCEPT… it destroys detail when you pass the matte into the mix. The work around is to double up the node and use it on the matte and fill independently, works… but doubles the render time (it’s a heavy slow node for rendering). I can handle that… fine, no drama BUT… it softens the image in the “focused” area! It also seems to offset it slightly as well. I guess this is all bugs right? Anyone else get this?

Here is the example, a cgi robot (scenelinear) with z-depth etc etc…

Image 1 is a simple A over B for reference.
Image2 is via the pyhsical defocus with near and far focus set to 0, and the matte piped in.
Image3 shows the “focus area” in magenta
Image4 shows the settings…

It shows how much detail get chewed up, also show how soft the ‘in focus’ result is. The pictures I’ve taken are very very tight (the actual render is much wider than appears), but it shows well the amount of softening that happens.

(running 2021.2/Linux/P5000)

I agree with you about needing to treat the matte separate with a duplicate of the node.

I haven’t been using Physical Defocus myself. I was going to set half a day aside and go through all of the various 3D depth of field options available and figure them out. There seems to be about half a dozen options. Your in focus doesn’t look very in focus does it?

I have always been very favorable to y_lens_blur
@andy_dill mentioned Frischluft’s LensCare as an OFX which excited me. What was the defocus tool the Nuke boys were using on Thor?

Cheers @PlaceYourBetts … it’s a fickle node (ignoring the issues above)… but once you iron out the quirks works really well.

I don’t think I have it. Was it a new addition? I am only on Flame 2020.3.1

This is what I have in my tool belt:

must only be 2021…

yeh its very close to being amazing! another issue is alphas that have any transparency/motion blur get eaten up when using the matte input along with the front and Z. again the hack seems to be treating the front and matte separately

If someone can show me how to actually use the 3D Blur node to properly composite I’d be forever grateful. My defocusing skills are super sus.

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My issue with the Physical Defocus is it seems to soften even the “sharp” slice. Maybe that’s just on shitass old macs, but I ran into that and jumped ship.

@randy, I can show you the 3d blur, but half of the demo will be me making arguments about why to not use it.

If I have to use a depth map I use the DOF node most of the time (at least until I wise up and buy Frischluft).

I believe the Nuke one everyone likes is “PG Bokeh”

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@andy_dill … so we agree that Physical Defocus softens the “sharp” slice… it’s not just your shitty old mac… not a great ‘feature’ of a blur node!


This is sad news. My hope was that specific shortcoming was hardware based.

I’ve always wanted to have access to Frischluft or any other OFX option. There’s another one that looks great but I can’t remember the name of it right now (not helpful, sorry). Anyways, I think Flame has to support the plugin for it to work so maybe we just need to make a feature request.

@andy_dill Sad indeed, as it does give excellent results otherwise… how it handles the blur ‘behind’ an object works much much better than crok DOF or the like…

Did the Frischluft OFX work well for you? I’m willing to cough up $250 if it works as advetised.

I remember trying the physical defocus on a job in beta. It didn’t seem to work as well as depth of field.

@andy_dill why don’t you like 3D blur? It’s fiddly but pretty much the same as dof no? I sometimes use it with that matchbox that has all the bokeh samples. Or grab my own.

PG Bokeh in my experience has all the same limitations as DOF in flame. I certainly haven’t found it any easier or quicker. You get the same edges issue and slices issue.

I must admit I can’t recall frischluft very well. I think it was so slow in Nuke that I gave up. You can test it in demo mode. Love to hear what others think.

YBlur I’d really like to love more but it too has limitations. I’ve used it on graphic type stuff with great success but on real film it struggles to get the fall off right.

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I haven’t tried it lately. There is a watermarked demo, and I’m gonna take a look at it on Monday. Cos yeah, I’ll gladly pay $250 for reliable DoF

Is it strange that reliable dof will drive me to always precomp if possible in Nuke? That, and Flame with CG passes makes me want to pull every hair from my fucking head…

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It’s strange but I don’t mind comping cg in flame. Having all the data and pipes hidden in Nuke really irritates me at times. However I do like the split out feature in Nuke (tilde isn’t it?). Having to press f4 to cycle through all the layers of a multi exr is less than perfect.

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I found Physical Defocus, to look great until the render, made the image wobble like heat haze… so i dropped it

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@jones Same here… switching the focus mode from “auto” to “static” helped get rid of almost all of that issue… almost all… the slices sample has to go up pretty high to really bury it.

@andy_dill Frischluft OFX works very very well. Does not chew up the render. Does not soften the image in the ‘sharp’ area. Spits out a dof’d matte (so no need to double up the node) does an excellent job all round. Also @jones it does not ‘wobble’ at all. You can plug in custom bokeh as well. I’ll be handing over the money asap.