Looking at the shoot I noticed this scene where the photographer is holding a filter at a diagonal angle as if he was trying to catch some light.
Does this technique have a name? And what kind of effect can I hope to achieve with it?
He is purposefully reflecting light from an off-camera light source onto the lens front element to create "lens flare" for 'artistic effect'.
(There's a small chance that he is doing something else but very probably not).
The hand held 'reflector' allows him to control the effect.
Aims are all the charming things you can get with lens flare when you don't want it, BUT now controlled (you hope) to enhance the image. Incomplete list of examples -
Effect name? "Lens flare" I guess :-)
He has a large off-camera light source which, based on various views in prior frames appears to be above him and somewhat off centre.
There is a flash of light on the model's head and hair very briefly as she flicks her hair just before the point you mention. Very hard to be sure of source direction but quite intense.
A reasonable explanation of his action given the above and the angle and probable source-direction is that he is purposefully creating "lens flare" by illuminating the front surface of his lens selectively.
This effect is briefly described in this SCRIBD ebook Fashion Flair for Portrait and Wedding Photography on SCRIBD pages 128-129 = book pages 111-112. ('Flair' and 'flare' being different here, of course :-) ). He says:
Lens Flare
When you start in photography, you learn that lens flare is bad. In truth, it often is.
Lens flare
occurs when unwanted light scatters within the lens, usually creating unwanted highlights or artifacts. This often washes out or desaturates the image, or it creates undesired rays of light within the final frame. That’s why we often use a lens hood to protect the front element of the lens, or we have someone hold shade over the camera to block unwanted light. There are even camera accessoriesmade specifically to help photographers block out the light.
Lens flare, however, can be used as an artistic tool. Commonly, fashion photographers utilize lens flare to make an image feel dreamlike or to emphasize the warmth of an environment. You can use this technique to make an image soft or dreamy, particularly when shooting near sunset. When you’re in the studio, you can purposefully create lens flare to build a surreal, glowing effect. In Figure 6.14, I achieved the lens flare by placing three strobes at full power on the background.The light bounces back, wraps around the subject, and refracts within the lens,creating this softening effect.
See above link for his version. Here's some approximate equivalents of mine. Bridesmaids were getting ready in front of large windows with very strong morning sunlight dominating the scene from behind. Along with "more normal" shots I tried numerous "into the sun" ones resulting in many that were just overexposed or so badly flared to be unusable. Plus a number that worked 'well enough. These two chosen for the into-the-lens light effects.
Here is an example of purposeful flare being used with sunlight to they say here {Wikipedia} "Enhance the sense of ascending - staircase at Borobadur. FWIW I have taken photos of the same scene without flare and I prefer mine - each to their own :-).
Here is an agh!!! iPhone post shot flare adding app - at least it's cheap :-).
Same app - now you can also add light leaks and glare and ... still 'only' 99 cents.
Extreme example where th ecreated flare is a major part of the end image.
Purposeful - Wikipedia - 'Perception of Christ Ascending to Heaven' Dome of the Rotunda of the church of the Holy Sepulchre Jerusalem Victor Grigas 2011 -1-19.jpg <- Full res via this link