Specify focus question

[Streetwise]

How is specify focus different from depth of field? If specify focus is checked, but DOF is unchecked, does specify focus even work? If so, what exactly does it focus on if the distance is different than the target distance? In other words, does it focus on the closest point, but then not drop off like DOF would? I'm just trying to understand how it works.

[Svetlozar Draganov]

Focus Distance is just another way to tell V-Ray where to focus in addition to the Target Distance.
By default V-Ray uses Target Distance as a focus distance but if you would like to link Camera Target to a specific object in the scene and at the same time to change to focus distance you could only do that by activating Focus Distance option.

The Focus Distance value will change Camera Brightness and FOV even if DOF is disabled.
The Focus Distance is displayed in the viewport by the middle line of the camera cone-icon:

[Streetwise]

The Focus Distance value will change Camera Brightness and FOV even if DOF is disabled.
The Focus Distance is displayed in the viewport by the middle line of the camera cone-icon:

That's interesting about the brightness changing. I never would have thought that connected to focus... But I'm still confused about Focus Distance as it would appear that it (and/or target distance) can be set on just about anything and the image still appears to be overall sharp. Am I missing something?

[vlado]

The DOF blurring depends on the f-number, the lens focal length, the system units, and the focus (or target) distance - make sure they all have realistic values.

Best regards,
Vlado