P:(Masking) Add a Depth of Field blur slider

[Matthileo]

Now that lightroom has masking advanced enough to take advantage of it, it would be nice if we could get a simple slider or set of sliders to add blur that looks like authentic defocus blur added directly to lightroom. 

[berliner_ffm]

Adding the global lens blur function is a good first step, but adding it globally is kind of counterintuitive.

The Lens Blur tool is by default a local adjustment since the focal plane has to be selected. However, we cannot take advantage of all local masking tools.

So to make it right I think, this tool should be split into two separate functions:

1. New Range mask that creates a depth map (not only like the existing one, that relies on embedded depth maps in the photo)
2. Local blur tool to add a blur effect to the selected mask

This would make the Depth Mask also available for other kind of local adjustments and the blur tool can also be used in conjunction with the other mask options, like Sky-, People- or Object-selection.

[Wurstkrapfen]

I would also be great to download the generated depthmap in greyscale to use it with other tools.

I can screenshot it, desaturate and invert it, but jus beeing able to save it as jpg would be so much easier (and better quality).

[Wurstkrapfen]

It's really fun to  play with https://depthy.stamina.pl/#/ just putting in any photo with an LR genereated depthmap.

[eye=art]

Thanks. But what's a depthmap useful for, in practical terms? How can one use it? 

[The paused momentum]

I want a feature that allows me to blur and denoise the selected area so that we can add effects like halation more accurately. 

[luxBorealis–TerryMcDonald]

Often, the Lens Blur tool provides a much too abrupt transition from un-blurred to blurred, particularly when the background falls away from, for example, a ground bird. I realize users can brush in various amounts of blur to reduce this transition, but a linear mask would be much more efficient.
For example: Within Masking, one could "Select Background" mask, then add a "Subtract Linear Gradient" mask, followed by invoking Lens Blur to the remaining mask. This would be highly beneficial and far more efficient.