Real Lens Flares

LENS PANE

VFX Real Lens Flares provides a tremendous amount of control over lens flare effects, but it isn’t entirely a build-everything-from-scratch affair (yet). The 36 bundled lens prescriptions deliver considerable variety and flexibility; the lens pane offers additional control over some lens aspects. However, you cannot (today) build a virtual lens from the ground up. In this User Guide section, we will explore the options you have for modifying the program’s existing prescriptions.

We recommend approaching the lens pane as you would think about an actual digital camera. You have a light source, a lens, and a sensor. The characteristics of the glass elements within the lens shape and affect how light travels through the lens and thus what artifacts those elements might create. Within the lens, the aperture restricts that light flow in certain ways, creating more artifacts, interactions, and image changes. The size of the sensor and its distance from the lens also impact the image.

By clicking on items in the lens pane, you expose detailed settings available in the inspector pane. Note that there may be more than one way to achieve an effect. For example, to tint an image blue, you could filter the light source or put a coating on one or more lens elements. Brightness may be controlled at the light source or the aperture. Differences may be subtle and up to your artistic perceptions and interpretations.

Light Source

The light source control group tied to the lens pane contains the same settings as when we first encountered the group via the presets browser. The only difference is that the lens pane’s light source now adds a read-only spectral graph. The graph provides a deeper view on color dominance within the original light source. This can be helpful if trying to match the profile of a certain light type, such as tungsten, LED, or fluorescent. Also, you might think of modifying the color filter as placing a gel over a light.

Note that increasing light source size can help soften a lens flare.

Aperture (detailed)

Clicking the lens barrel aperture (above) brings up the detailed aperture control group in the inspector pane (below). Because the aperture is one of the most critical components in lens flare creation, it will be worth your time to study and experiment with the following settings to achieve truly remarkable flare results.

F-stop values can span from 0.9 to 22.

VFX Real Lens Flares requires at least three aperture blades, which produce a triangular flare shape. You can scale up to a maximum of 17 blades, which will appear nearly circular. In the following image, you’ll see how using four aperture blades results in squarish lens reflections.

Some apertures use curved blades with twists and notches where the blades overlap. VFX Real Lens Flares provides control over each of these variables.

• Curvature. Values span from -100% to 100 percent. Adding curvature spreads out spikes. A 100% curvature creates a glowball while negative curvature yields scalloped spikes.
• Twist. Values span from -100% to 100 percent. In effect, switching between these extreme values inverts the aperture shape. Twists tend to produce a scalloped aperture shape.
• Notch. The notch can be set from -45° to 45. Pronounced notches tend to produce a “sawtooth” appearance.
• Notch angle. Even the skew of the notch can be adjusted, with values from 0° to 45 degrees.
• Angle. This adjusts the rotation of the aperture.

Taken together, these options can provide some distinctly unusual geometries for lens flare effects.

Diffraction is a recent addition to VFX Real Lens Flares. The feature simulates how light waves bend around the aperture’s edges. This subtle effect creates a ripple effect in reflections. The higher the diffraction value, the more noticeable the ripples. Let’s nerd out on this for a moment.

Can you see the ripples? Perhaps not, depending on how you’re viewing these images, so let’s spotlight the differences.

See it now? The ripples are clearer on the larger reflections to the right, but also note the changes to the smaller reflections on the left. At 100%, we’ve exacerbated the diffraction effect far more than you’d likely ever encounter it naturally in a lens. However, all lenses exhibit some amount of diffraction, and Maxon’s default value of 35% may or may not be close to the true diffraction found in the physical version of your simulated lens. Experimentation could get you closer to “reality,” if desired.

Fun science note: Why ripples? Think back to high school or undergraduate physics. Essentially, a lens aperture is a single-slit diffraction experiment. Read the linked Wikipedia article for a refresher. The upshot is that all waves diffract as they pass around obstacle edges. The rippling effect is a manifestation of light waves exhibiting this phenomenon.

Next, the detailed aperture control set offers three settings related to imperfections. No machining process is perfect, and every real-world aperture blade contains microscopic edge inconsistencies. These imperfections can be modeled as algorithmic noise. The perlin noise manipulations used in core projections have similar application here. Observe in the comparison below how accentuating imperfections results in more diffuse starburst spikes.

Finally, the detailed aperture control set offers two advanced functions:

• Rotate with stop. In physical lenses, the aperture shape appears to rotate as the user adjusts the f-stop. Rotate with stop controls the proportion, or “speed,” of that rotation. Values can range from -50 to 50. A value of 0 means no spin when the stop is adjusted.
• Reduce curvature with stop. Values range from 0% to 100 percent. At 100%, curvature approaches zero as the f-stop value approaches its maximum.

Lens Elements

Each lens prescription contains several lens elements. As mentioned, users have no control over the number, size, and shape of these elements yet (apart from picking a different lens prescription), but you can control certain characteristics of each lens’s coating. The coating determines the amount of color transmission through that lens. This ultimately determines what color the reflections appear as.

Coating changes won’t affect core projections, but they do influence reflections. By adjusting the thickness and anti-reflective (AR) properties for the front and back of each lens element, you’ll see subtle reflection changes emerge. Remember that lens elements operate in tandem; experimentation across multiple elements may be needed to see even subtle results.

The refractive index, which controls how fast light moves through the lens, can be set from 0.00 to 2.00.

Chroma dispersion, which ranges from 0% to 100%, influences how the lens element is prone to chromatic aberration.

Image Plane

The image plane is the surface upon which the lens focuses an image for capture. These days, the image plane is commonly called the sensor, but VFX Real Lens Flares includes prescriptions for both digital and film camera lenses, so a more generic term is most accurate.

You might have noticed that changing the light source’s color results in a changing of the light path’s color as represented in the Lens Pane. Similarly, changing the image plane’s position in the Inspector Pane will scoot the sensor toward or away from the lens. For convenience, VFX Real Lens Flares incorporates a pull-down list of common camera types to help mimic real-world accurate image plane settings.

The closer a sensor is to the lens, the less projected that image will be. A closer position tends to result in a reflection pattern that hugs closer to the flare’s light source. Greater distance means the projected image has more chance to expand, and so reflections may seem to occupy less space. Conversely, the smaller the sensor size, the more reflections tend to diffuse and fill the image. Larger sensor sizes create more space around flares.

Be aware that modifying image plane settings alters the look of reflections, not core projections, as illustrated in the following comparison.