DOF and Motion Blur in Animation

[cristoforo]

Anyone have any tips on using DOF and Motion Blur in animations?

[Morbid Angel]

your question can be asked:
can you give any tips on rendering?.. yes you can, infact many. If you can be more specific, then we can answer.

Usuaylly in film, we match motion blur to the live action plate, and they provide us with cameras information which is then input into vray. For example, realworlds camera shutter speed can be 1/24th 1/48th and so on, then this is input into vray with a conversion where 1/48th would be 0.56 motion blur duration.
regarding the dof, usually its output as a zdepth pass and composited. This allows for more control. If your dof is embedded, then you have no control. Also render time would be quite affected.
If you are hard pressed for render time, then motion blur can be output as a motion vector for post composite as well.

[cristoforo]

I'm not matching the animation to other footage....so I imagine that setting of .56 will work the same for me? Is motion blur only for objects in motion or does it also work well for say a tree in the foreground that you quickly walk by? Does this affect render time much? I'll have to read a bit on the zdepth.....Is this rendered out while I am rendering each frame or must a do a separate sequence? I can composite this later in Adobe Premiere? Thanks for help!

[Morbid Angel]

I see, well 0.56 seems to be a good setting all around.
When motion blur is on, all objects become motion blurred. That is the way it works. But that doesnt mean that all of them will motion blur if the camera is static, for instance, only moving ones will.
Render time will be affected. But depending on your scene complexity. Usually double the time, as it needs to calculate 1 sample on current frame and 1 sample for the next frame.
Zdepth is a gbuffer option, it will be calculated on render time, so all you need to do is specify to output it.
I wouldnt recomend compositing in premier, its not a compositing packedge. If you are not familiar with compositing, after effects can be a good start, simple and robust. But more complex compositing is done in programs like shake or fusion.
The problem with the post zdepth is that it wont look as good as the vray one. Since its a post process it all depends on the plugin which uses zdepth to blur pixels. If your plugin supports options like bokeh then you might get a good result, check out richard rosenman's dof tool.
Have fun.

[cristoforo]

Thanks for all your help....I'll have to look into after effects. I should probably just leave out DOF and motion blur for this project since it is my first animaiton with vray.....do not need to make the render times any longer now! Thanks again!