Depth of Field

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Depth of Field

Postby zukazuka » Mon Jul 12, 2010 5:38 am

I've been playing around with Depth of Field - very cool - this is the first time I've tried it...

A few questions:

AutoFocus - this focuses on the first face that that is hit from a beam shot from the center of the camera.

Object - focuses on the center point of an object.

It would be cool if there was another mode like "FrontObject" where it focuses on the closest face (front) of the object specified instead of the object center.

In 0.7 (with luxblend 0.7) I can't get the "use f/stop" to work it seems to have no effect, but the lens-radius method works great...
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Re: Depth of Field

Postby zsouthboy » Mon Jul 12, 2010 8:49 am

RE: your request: note that most people just add an empty to the scene and use that as the target object for focus. You can then position the empty wherever you'd like, at the front of another object if you'd like :)
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Re: Depth of Field

Postby zukazuka » Mon Jul 12, 2010 8:53 am

zsouthboy wrote:RE: your request: note that most people just add an empty to the scene and use that as the target object for focus. You can then position the empty wherever you'd like, at the front of another object if you'd like :)


Good idea! never thought of that!
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Re: Depth of Field

Postby SATtva » Mon Jul 12, 2010 10:31 am

zukazuka wrote:In 0.7 (with luxblend 0.7) I can't get the "use f/stop" to work it seems to have no effect, but the lens-radius method works great...

How's that? When using f/stop it gets converted to lens radius on export. If lens radius works, f/stop should too (don't forget: smaller the f/stop -- heavier the DoF effect).
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Re: Depth of Field

Postby zsouthboy » Mon Jul 12, 2010 1:47 pm

Good point, two possibilities:
1) The scene scale is way, way off.
or
2) The fstop he's choosing is very high, and he's choosing other high-numbered apertures to compare against. It's going to be completely unobvious of any difference between f/16 and f/22 in a normal indoors scene, depending on scale and focal point.

zukazuka, can you show or tell us what you were setting specificially ?
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Re: Depth of Field

Postby zukazuka » Mon Jul 12, 2010 5:14 pm

Hi, I'm experimenting with more wide angle aperture settings like F2.8 and smaller number (wider aperture).

I created a simple model with 3 cubes about 2 units which I'm guessing is always equal to meters - (standard new blender object), camera about 5.56 units away from first cube (cubes spaced further and further away for distance) - YES I do notice depth of field now... But I've got it set down to like F0.5 and I was expecting the depth of field to be so thin that only a little is in focus.

Just for reference I have a 50mm F1.2L canon lens for my camera - at F1.2 the depth of field is so razor thin you have to be really really accurate with your focus. I'm finding that if I set lens radius to about 0.3 it gets the type of results I'm trying to achieve. So yes it is working, and yes I guess you could say I'm working at the more extreme ends of the scale... Even at F2.8 I would expect the depth of field to be a lot thinner than it actually is...
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Re: Depth of Field

Postby zukazuka » Mon Jul 12, 2010 5:20 pm

Here's a sample I'm playing with:
dof.jpg

dof.blend.zip
(37.7 KiB) Downloaded 34 times

At F0.5 I would expect the further cubes to be totally blurred...

I added a point light in the middle, trying to get some boake effects...
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Re: Depth of Field

Postby zukazuka » Mon Jul 12, 2010 5:23 pm

This is more what I would expect F0.5 to look like:
blurred.jpg

I achieved this result by setting the lens radius to 0.2-0.3
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Re: Depth of Field

Postby zukazuka » Mon Jul 12, 2010 5:32 pm

I tried creating an empty and setting the that object as the focus target. This is working good, but in a few cases maybe the camera angle or something is making it not seem to focus where I want. If the empty is in the corner of the camera image would this distort it? does the empty have to be relatively near the center of the camera field of view or are there any other limitations that you can think of?

This is some cool stuff man! I can't believe I haven't tried DOF earlier... redoing all my models now with some DOF hehe...
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Re: Depth of Field

Postby zsouthboy » Mon Jul 12, 2010 6:48 pm

Ah, as I suspected: your scene scale is HUGE. In luxrender, you HAVE to use the right scale for your models.

The blender default cubes are 2 meters long/wide/deep. (measurements in luxrender are expressed in meters, for the most part).

Try shrinking your entire scene by a factor of 10; there is a worldscale setting in luxblend that you can adjust (set it to 0.1).

The reason you get such a strong DoF effect on that second scene is that your aperture size is 0.2 m!
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