Hi Stu,
I might explain now more than you need, but bear with me, as this is a public thread ;o)
Lens-flare is given based on the inter-reflections of the lenses, in detail: each glass element in a lens has the option to reflect the light back and forth.
This is not a static quality—in other words, each lens model will create its own unique lens-flare. (If they are build equally and coated in the same way, they might not differ at all)
As a rule of thumb, the older the lens, the more likely it is, that the lens flare is stronger. Basically related to the quality of the coating of each lens, coating these days are so much better, hence lens flare and stronger contrast. There are some people (today!) who take the coating for one or more elements of the lens away. (Duclos Lenses or Dog-Schidt have offers for that). Each lens old, new or treaded has a unique flare as I mentioned, and especially Panavision/Cinemascope lenses show a very specific one. Film-makers test lenses especially for that, or even record in a black studio those, for compositing work later on.
The light source for a lens flare doesn’t need to be in the visible frame of the camera! It can be produced by any light that hits the front element of a lens (hence the lens hood to avoid it). One of the main users in the last decade was certainly J.J. Abrams—who often even shows his manually flaring with handheld light source in “behind the scene” clips.
In the past twenty years it has become a “trademark” for CG creation, as it produces the aesthetic of practical camera work. However, if done carefully, it can provide a look and feel, that provides perhaps more information about the scene itself, than any direct light in the scene itself. I make a difference here in a) fog like flaring (more atmospheric) and b) classical lens flare, the line of many single colorful reflections (disc-like) which supports more the indication of the motion of the camera (or just simulates it)
A good camera work in the past was always based on keeping the Lens clean, wich meant to use Matte-Boxes with “French-Flags”, to keep the spot light out. Older glass had enough to do to deliver a contrast rich image based on the weaker coatings of the elements. With newer lenses, the look is more clean and perhaps sterile, hence the artificial flaring these days.
Either way, it produces an aesthetically effect—which should be used wisely, as it transfers more than just being cool. Film and animations depend on a temporal-contrast as well—we get used very quickly to anything in the frame, if I might speak as a cinematographer—with a love for motion graphic. Here is the reason why most film-makers, me included, have many lenses in many versions, long story, and not limited to flare of course. Each lens has its own qualities. It fills days or years of discussion.
Dust by itself shows and doesn’t show at all perhaps. But if wide open (aperture) anything in front of the lens will show (eventually). You might have seen in the blooming (Bokeh) sometimes sand like inclusions, which can come from Black-Diffision filters, etc., also a long story. An increase in dynamic range is sometimes a target (as the blacks get more light, the camera can be shifted to towards the highlights.)
Long story short, as I mentioned it in some of my series, Lens Flare starts in the lens (sound logically)—which means nothing can be in-front of it. Here starts the problem if you compose images (CG with CG or Practical with CG, and Practical with Practical). In the moment you have your flare baked in the image, you need to re-porduce it very carefully for any extra foreground element. Sometimes nearly impossible to do in a certain amount of time.
As we have the luxury in C4D to separate such things, to a certain degree, in Multipass or several pass renderings, I would suggest to analyses the scene as well as the post production, and go from there.
To your question,
In C4D the light source by default will not produce any lens-flare. You might set a light source up to visible for an atmospheric effect, which doesn’t need to illuminate anything. Or you can set up Lens flare in the Attribute manager of the Light source itself. If there are 10 strong light sources, then chances are that there are ten options for lens-flares.
Again, get clear what you want and need. Just to place lens-flare for no reason, will water down the effect and you have to make it much stronger where you need it perhaps. It should be based on a decision, not on an automatic or always on. Too much never helps, the right amount is always based on a masterful eye.
All the best
Sassi
P.S.: I can expand on that, in a series, if there is enough interest. Starting with example among many lenses, captured with my RED Epic, and then discuss the options based on the practical exploration in CINEMA 4D and of course in post production. For film and as MotionGraphic enhancer. (Tutorial Request Forum :o)
