Oval, cat's-eye-shaped blur circles at frame edges caused by mechanical vignetting at wide apertures — an optical artifact some cinematographers embrace, others avoid.
What is Cat's Eye Bokeh?
Cat's Eye Bokeh (English: Cat's Eye Bokeh or Lemon Bokeh) refers to oval, cut-off out-of-focus circles at the edge of the frame that resemble cat's eyes. It is caused by mechanical vignetting at wide apertures – the light is clipped at the edges by the lens housing.
Technical Definition
| Aspect | Details |
|---|---|
| Cause | Mechanical vignetting |
| Position | Frame edges |
| Shape | Oval, flattened |
| Occurrence | At wide apertures |
How is Cat's Eye Bokeh Created?
The Principle
| Element | Description |
|---|---|
| Image Center | Light passes unimpeded |
| Frame Edge | Light is clipped |
| Aperture | Wider = stronger effect |
| Result | Oval instead of round circles |
Factors
| Factor | Influence |
|---|---|
| Aperture Opening | Wider = more Cat's Eye |
| Lens Design | Retrofocus often affected |
| Focal Length | Wider angles more so |
| Filter Thread | Can amplify |
Appearance
Characteristics
| Aspect | Description |
|---|---|
| Center | Round bokeh circles |
| Edge | Oval, "squashed" circles |
| Direction | Pointing towards the image center |
| Transition | Gradual from center to edge |
Variations
| Name | Description |
|---|---|
| Lemon Bokeh | Lemon-shaped |
| Football Bokeh | American football shape |
| Oval Bokeh | Neutral description |
Evaluation: Flaw or Character?
As a Flaw
| Argument | Explanation |
|---|---|
| Distracting | Draws attention |
| Uneven | Inconsistent image |
| Modern | Clean look preferred |
| Commercial | Often undesirable |
As Character
| Argument | Explanation |
|---|---|
| Vintage | Authentic look |
| Organic | Less sterile |
| Recognizable | Lens signature |
| Artistic | Deliberate choice |
Lenses and Cat's Eye
Strong Cat's Eye
| Lens Type | Example |
|---|---|
| Vintage | Canon FD, Minolta MD |
| Budget Fast | Inexpensive f/1.4s |
| Wide-Angle | 24mm and wider |
| Retrofocus | Typical construction |
Minimal Cat's Eye
| Lens Type | Example |
|---|---|
| Master Primes | ARRI/Zeiss |
| Signature Primes | ARRI |
| Modern Cine | High-end |
| Aspherical | Corrected designs |
Avoidance and Usage
Minimizing Cat's Eye
| Method | Description |
|---|---|
| Stopping Down | f/2.8 instead of f/1.4 |
| Lens Choice | Corrected optics |
| Composition | Highlights in the center |
| Cropping | Cut off the edges |
Deliberately Using Cat's Eye
| Application | Effect |
|---|---|
| Period Pieces | Authentic look |
| Music Videos | Stylized |
| Indie Films | Character |
| Portraits | Framing bokeh |
Related Bokeh Phenomena
| Phenomenon | Description |
|---|---|
| Swirl Bokeh | Spiral movement |
| Onion Bokeh | Onion rings |
| Soap Bubble | Soap bubble edges |
| Nervous Bokeh | Unsteady structure |
The Legacy
Development
- Early Optics: Cat's Eye was normal
- Modern: Correction possible
- Digital: Visible again
- Today: Deliberate stylistic choice
Influence
Cat's Eye Bokeh has evolved from a technical flaw to an aesthetic tool – an example of how imperfection becomes a stylistic element.
Today
| Aspect | Details |
|---|---|
| Frequency | Depends on lens choice |
| Avoidance | Through lens design |
| Usage | Deliberate stylistic choice |
| Trend | Retro looks appreciate it |
Modern Situation
High-end cinema lenses minimize Cat's Eye, but the trend towards vintage looks has made the phenomenon popular again – as a deliberate stylistic device rather than a mistake.
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