Putting Your Lens Flare On The Spot
This tip lets you precisely position the center of the Lens Flare filter by using the Info palette and a little-known feature of the Lens Flare dialog. First, open the Info palette (found under the Window menu), then put your cursor over the precise spot in your image where you'd like the center of your lens flare to appear. Look in the Info palette, under the X and Y coordinates, and write down those two coordinates (I knew one day I'd find a use for the X and Y coordinate readings). Then go under the Filter menu, under Render, and choose Lens Flare. There's a fairly large preview window in the center of the dialog. Hold the Option key (PC: Alt key), click once on the preview window, and it brings up the Precise Flare Center dialog. Enter those X and Y coordinates you wrote down earlier (you did write them down, right?), click OK, and your lens flare is precisely positioned.
In CS3 all you have to do is click the spot in the photo with your mouse pointer then go to Filter -> Render -> Lens Flare. The lens flare will be positioned where you clicked.
Also, you can just reposition the lens flare with your mouse in the preview window.
Unlike true lens flare, this artifact is not visible in the eyepiece of a digital SLR camera
Lens flare is created when non-image forming light enters the lens and subsequently hits the camera’s film or digital sensor.