Smart Filters allow you to change the settings of filter effects in Photoshop at anytime, providing a significantly more flexible nondestructive file structure. Smart Filters can only be applied to Smart Objects. Convert a rasterized layer or group of layers to a Smart Object by highlighting it/them and going to Layer > Smart Objects > Convert To Smart Object.
You can do many things with Smart Filters—switch them on or off, change their Opacity or Blend mode, mask them or combine multiple filter effects (you only get one mask for all of the Smart Filters applied to one Smart Object); using Layer Blend If sliders isn’t one of them.
Use Smart Filters sparingly, as the price you’ll pay for this flexibility is a significant increase in file size, as much as four times, which slows processing and saving time—but don’t write them off because of this.
Blur Tools filters—Tilt-Shift, Field Blur, Iris Blur—offer simplified interfaces, easier filter setting selectivity (though limited to hexagonal iris shapes), stronger intensity and faster performance than the Lens Blur filter. Not only can these filters be easily applied as Smart Filters, but they’re best applied as Smart Filters; apply one filter, and two new palettes will appear, Blur Tools and Blur Effects, which can be further adjusted in the future if the effects are applied as Smart Filters.
The Blur Tools palette allows you to activate one, two or all three of these filters and adjust the sliders that control each effect. The Blur Effects palette offers three sliders: Light Bokeh (this slider brightens bokeh effects), Bokeh Color (this slider increases the saturation of affected areas) and Light Range (this slider adjusts the range of levels affected, allowing you to target effects into shadows, midtones or highlights—more effectively than Lens Blur’s Threshold slider—and it intensifies the tonal range between the sliders, producing a more realistic effect).
Sooner or later, you’ll wonder how applying a filter selectively through its controls is different than applying a filter to a duplicate layer uniformly and then adding a mask. Sliders that provide selective application of an effect offer variable intensity, blurring an area more or less, while a layer mask selectively reduces the opacity of a uniform effect revealing the focused image below. The effect produced by these two methods can be significantly different.