Out of Focus Lights/Bokeh Specifics

[Michael Notar]

was noticing on a recent film, background out of focus points of light, perfectly round, has small speckles/dust... what causes that?

[Matt Ryan]

dust and or dirt on the sensor or the back element of the lens.

My best guess is dust on the rear element or inside the lens or on the front element.

[Tom Savige]

You may also find that softening filters such as Pro Mists or Classic Soft will give you the same effect. I would say that in most cases, it is probably a Softening Filter.

[Rob Ruffo]

100% it's a diffusion filter.

[Matt Ryan]

Well it depends? Is it consistent across the entire bokeh? or is it just a few random specks?

[Dr. Sassi]

Sometimes a (large) fabric like net is placed behind the actors to "filter" the brightness from the background, which causes a pattern in the bokeh. As you have not posted an images, I'm not certain if we have the same in mind, as you mentioned a more random pattern.

[Matt W.]

100% it's a diffusion filter.

Yep.

[Michael Notar]

its random in some spots but not others. its not my footage but movies i see on tv. perhaps a dirty window on set...? doesnt look like sensor dust (like what you would see in digital still photos).

[Adrian Correia]

I'd say it's diffusion filter too - I saw it particularly in Abraham Lincoln Vampire Hunter

[Matt Ryan]

If it's a filter though it will have a consistency across all the bokeh and not just random specks.