big fogged out flares

Ian Coad · February 7, 2009

i've got a second year advanced project coming up in a month or two that i'll be dp'ing.

i'm interested in doing - for lack of knowing its true terminology - what i would call, 'big fogged-out flares'. see the attached photos for references of what i'm talking about. essentially, its where the flare floods the entire image frame. i'm trying to pinpoint, or understand the physics of the way light - or a particular kind of light - hits the lens and fills the image with this fog like effect. please understand that fog fx, or a fog machine will not be on set, and from what i'm seeing it would be unnecessary - this should be a result obtained solely through flaring the lens.

one thing though, i do seem to be seeing that this effect for some reason occurs more often and more naturally on longer lenses. the images i included were taken with my canon rebel xti with a 50mm 1.4 lens.

thanks.

- ian.

Ian Coad · February 7, 2009

oh and one other thing i wanted to know is if particular filters reduce the probability of getting such a flare.

Satsuki Murashige · February 8, 2009

That type of flare is called veiling glare. It's caused by a combination of a strong backlight source just out of frame and the use of older lenses with less efficient coatings. It's been my experience that a longer lens is more likely to exhibit veiling glare than a wide angle, don't know why though. Maybe it has something to do with the design? Try shooting wide open as well, since those older lenses sharpen up and get more contrasty when stopped down. You can even find cine lenses that have been stripped of their coatings at certain rental houses (Panavision has a set called "flare" lenses).

Phil Rhodes · February 8, 2009

Most lenses will do it to a certain extent if you fire light into them, although some more than others. It is seen as undesirable and big, expensive lenses like digiprimes and Cooke S4s don't seem to do it much, but my experience at the super high end is limited - most video zooms do it very readily.

Fog filters will give you a sort of kind of approximation, but if you illuminate them too strongly you'll end up veiling the whole frame, with concomitant problems of casting visible shadows on the filter and causing highlights to flare regardless.

Most of this, I suspect, is about putting big lights pointing at the camera, just out of shot.

P

Ian Coad · February 8, 2009

that was very helpful. thank you so much guys.

Satsuki Murashige · February 8, 2009

I've noticed veiling glare mostly with older 35mm SLR lenses, 70's vintage Nikkors and Pentax. You could try to find old cine primes like the Cooke Speed Panchros or B&L Super Baltars. Or even older zoom lenses like the Cooke 18-100 and Angenieux 25-250.

Most lenses will do it to a certain extent if you fire light into them, although some more than others. It is seen as undesirable and big, expensive lenses like digiprimes and Cooke S4s don't seem to do it much, but my experience at the super high end is limited - most video zooms do it very readily.

Now that you bring it up Phil, I've noticed that a lot of the newer Zeiss lenses like the Digiprimes and Ultra 16's will flare green around a point source. I find it really ugly and prefer the red halo that you get around point sources with the older Superspeeds. Strangely, I've noticed that the Master Primes have the same red halo flare as the Superspeeds, although they presumably share the same coatings as the Digis and Ultra 16s. I wonder if they were designed that way? I remember reading in American Cinematographer that Dan Sasaki (former lens guru at Panavision) was able to make custom 'scope lenses for "The Prestige" that flared in a very precise way by tweaking the coatings of various lens elements.

Satsuki Murashige · February 8, 2009

*EDIT: Filters should increase the likelihood of flares because there is now an additional layer of glass in between the subject and the image plane, thus increasing the chance of additional reflections. Flares are really reflections off of glass elements in the lens (or in front of it). The lens coatings help to suppress those reflections by absorbing light, thus rendering a more contrasty image. Of course, if you're using filters then you're probably using a matte box which shades the lens from stray light and negates a lot of the reflections creating the flare in the first place, so unless you need the ND to shoot at wider apertures, it's probably better to just shoot without the matte box at all.