KNOLL LENS FLARE - Centre Point

[marc conduit]

Can you control the centre point of a KNOLL Lens flare? I know how to control the flare location. But having made the swap from other lens flare plugs I am battling to see how to control where the centre of the flare is located. It just seems to all point to the middle of the screen, Any help would be awesome! Rick Gerard​ you mentioned having some insights?

[Rick Gerard]

I am not exactly sure I understand exactly what you are trying to do. All lens flare effects that I know of are based on basic optical principals. The flare position would be placed where a light source would be in the scene. The refraction, the look of the flare, is calculated by predicting the color and placement of the refracted light based on the actual behavior of light passing through a lens. The center of the lens is the center of the lens and there's not much that you can do about that.

If you move the light source (flair center) then the refracted light is going to move in the frame. If you need a halo to be in a certain position then you have to move the source point to a spot in the frame that will put the halo where you want it.

Please include a screenshot showing us what you are trying to accomplish. That would help us give you some tips.

[marc conduit]

okay will send a screenie now..

[marc conduit]

So I optical flares that I used for may years you could move the

centre point.. the area that the little falloff flares happen. with

knoll that I am learning I can't see how to move this area.. see the

drawers to describe this. does it make sense? 

[Rick Gerard]

Optical Flares does have a center point. This creates an unrealistic lens flare that is some times useful for doing things like reflections on objects in the scene. Let's say that you have a pitcher of water with a light source behind and to the left. You would get one flare from the lens, which is always around the optical center of the camera, and you could get another flare actually on the picture of water that is not centered around the optical center of the camera lens, but on the optical center of the lens formed by the glass and the water. This flare would not extend past the surface of the pitcher of water but would have to be masked to be realistic.   While you could accomplish that effect using Knoll Light Factory (if my memory serves) you would have to pre-compose and mask the effect, then add another copy of Light Factory to the scene to give you a lens flare caused by the light source.

Did you follow that? Video Copilot's Optical Flares is a little more versatile in that way.

Once again, if we had a screenshot and an explanation of what you were trying to achieve then we could give you a better idea of how to handle the problem. It might be as simple as creating a black solid that is larger than your composition frame, moving the layer position so the new center of the layer (default anchor point) is where you want the new optical center to be, then positioning the light location where you want it to be. Then you could either check Render Alpha or set the blend mode to Add or Screen to composite the flare into your scene.

[marc conduit]

so with some flare plugins you can cheat the centre point and move this around (purple screen grab), I found i used this a lot instead of just having the flare orientate to the centre of the screen. uses like secondary flares through glass etc that did not need to have a 'true'  centre point.

It seems you can not to this with knoll? It is accurate I am aware, but a little cumbersome for some cheats. All flares go towards centre of screen9 orange screen) You can not position this centre so to speak.

I am trying to understand if this is the case in hwich case i need to figure a workaround, or if i am missing a simple solve to position the centre of the flare

All of this is not speaking of the flare position. That is simple enough.

Does this make sense?

[marc conduit]

[Rick Gerard]

Funky lens flare with center offset as in your second example:

Oversized layer, check the info in the Project Panel, gives me. the ability to reposition the anchor point of the layer which simulates a new optical center, rotation, and scale to simulate an anamorphic lens. Exactly what you want to do with even the simplest or Lens Flare effects. Making the layer 3D gives you even more control of the shape and position of the flare:

These effects are completely unnatural and could not be re-created with a real camera and light, but they may be an effective part of a realistic design if you were to use them as reflections on other geometry in the scene. You can precisely recreate both of these frames by observing the modified properties of the layers in the screenshots.

[marc conduit]

In recon give users control of the centre point. Honestly.

What you think?

Marc Ziman - CONDUIT.

www.conduit.co.za

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[Rick Gerard]

I used Knoll Light Factory for years and I can't ever remember feeling the need to offset the optical center. My primary lens flare tool now is Video Copilot's Optical Flares. It does have the option to move the optical center position, and I use it occasionally. Most of the time I'm trying to create realistic effects so manipulating the optical center is pretty low on my list of requirements. If I'm building reflections I usually just go old school with a colored solid, a mask, a feathered edge, some blur, and a blend mode.

Light Factory is a good tool for some designs but I don't find it as flexible or as easy to work with as Optical Flares. If you want the ability to change the optical center you should send a feature request to Red Giant.