Depth of Field question

[andyH]

Anyone know what the relationship is (if any) between the f stop parameters in the Camera Object Properties -> Multi-Pass Effect and the Mental Ray Renderer -> Camera Effects?

 

When selecting Depth of Field (mental ray) in the Camera Multi-Pass Effect roll out is it overiden by the f-stop value in the Mental Ray Renderer Camera Effects rollout?

 

Any insight would be appreciated.

 

Thanks.

[erickdt]

I'm not sure about Mental Ray in particular as I do not use it but in photography in general, a larger aperture (higher F number) will produce a more pronounced DOF effect.

 

E

[aaronrumple]

You may want to do your DOF in post with a ZDepth pass. You'll have more control and can get a more pronounced effect. You have to use a very large F stop to get an effect with the camera.

[erickdt]

I would second that suggestion.

 

E

[andyH]

You may want to do your DOF in post with a ZDepth pass. You'll have more control and can get a more pronounced effect. You have to use a very large F stop to get an effect with the camera.

 

OK Sounds like a plan, now I need to go and google ZDepth pass and figure out how to do that

 

I wouldnt mind knowing how the two f-stop paramaters interract tho, so if anyone else has any ideas I would still appreciate some insight.

 

Thanks for the replies so far.

[aaronrumple]

OK Sounds like a plan, now I need to go and google ZDepth pass and figure out how to do that

 

I wouldnt mind knowing how the two f-stop paramaters interract tho, so if anyone else has any ideas I would still appreciate some insight.

 

Thanks for the replies so far.

 

From the help file:

Multi-Pass DOF:

Important. This effect is for the default scanline renderer. The mental ray renderer has its own depth-of-field effect. See Depth of Field Parameter (mental ray Renderer).

[andyH]

Well the multi-pass dropdown box actualy has a selection for "Depth of Field (mental ray)" so I am pretty sure that the help is a bit missleading there. I am at work so cant check at the moment.

[aaronrumple]

I see what you're asking now. The camera setting is applied to a specific camera view. The renderer setting is applied to perspective views (no camera).

[andyH]

I see what you're asking now. The camera setting is applied to a specific camera view. The renderer setting is applied to perspective views (no camera).

 

Ahh I see, so if rendering a camera view then the f-stop that is configured on the camera applies, and if rendering a perspective view the one in the mr render settings special effects roll-out...

 

Bingo, and thanks for the reply...

 

It does look as though a zdepth pass is the most efficient way to go tho, so I will probably be using that in the future...

 

thanks a lot for clearing that up!

[Crazy Homeless Guy]

I don't use a lot of DOF myself, but I would caution to make sure you are using it appropriatly. It is rare that is is used in arch vix effectively without looking awkward. A good rule to start off might be to only use DOF that could be created by a physical lens. This means you will need to study how DOF actually works with a physical lens to make sure that you are not overdoing it in your scene.

 

Also, DOF/Bokeh from a lens is more sophisticated than simply applying a gausion blur to a Z-Depth pass. I would research plugins that specialize in recreating Blokeh to use in combination with your Z-Depth pass.

[aaronrumple]

Also, DOF/Bokeh from a lens is more sophisticated than simply applying a gausion blur to a Z-Depth pass. I would research plugins that specialize in recreating Blokeh to use in combination with your Z-Depth pass.

 

Correct. Photoshop's Lens blur is a much better tool to use.

[andyH]

Noted on all of those points chg.. the current project I am working on is actually a product visualization, and i need some dof for the closeup shots to add a bit of realism. So i think a zdepth pass will probably work as the effct will be quite subtle. I will take a look at the Blokeh plugins (whatever Blokeh is!) as it would be good to know how to use dof correctly for arch viz if I need it in the future.

 

I will also take a look at the ps lense blur tool,

 

Thanks for the input everyone.

Edited April 13, 2010 by andyH