FRENEL FoV & DoF Calculator

• Angular Field of View (°): The angular cone of light captured by the sensor, determined strictly by active sensor size ($d$) and focal length ($f$).
• Linear Frame Coverage (m): At a subject distance $D$, the physical width and height of the scene captured in-frame is Width = D × (Effective Sensor Width ÷ Focal Length). For example, on a 36mm Full-Frame sensor with a 35mm lens at 3.0m distance, your horizontal frame width is roughly 3.09 meters.
• Why Cinema Matches Horizontal FoV: Because cinema sensors vary in aspect ratio (3:2 Open Gate, 4:3 Anamorphic, 17:9 DCI, 16:9 UHD), matching by Horizontal FoV ensures actor blocking and left/right set edges match identically between A and B cameras.

• What DoF Actually Is: True optical focus exists at only one mathematical plane. Depth of Field is the zone in front of ($D_{\text{near}}$) and behind ($D_{\text{far}}$) that plane where out-of-focus blur circles remain smaller than the sensor's Circle of Confusion (CoC).
• Why "1/3 Front, 2/3 Rear" is Only a Rule of Thumb: At close-up/macro distances, Depth of Field splits almost 50% in front / 50% behind the subject. As you focus further out toward the Hyperfocal distance, rear DoF expands rapidly until it reaches 100% behind at Hyperfocal. Check Box #4 above (DoF Split F/R) to see the exact live front/rear percentage for your shot!

When a point of light is out of focus, it projects a blurry disc ("blur circle") onto the sensor. The Circle of Confusion (CoC) is the maximum diameter that disc can have before a viewer sitting at standard theater distance perceives it as unsharp. Because a smaller Super 16 sensor ($14.9\text{mm}$ diagonal) must be enlarged nearly $3\times$ more than Full Frame ($43.3\text{mm}$ diagonal) to fill a cinema screen, its CoC limit is nearly $3\times$ stricter (0.010mm on S16 vs 0.029mm on FF).

Hyperfocal Distance ($H$) is the closest focus distance at which the lens can be set while keeping Infinity ($\infty$) acceptably sharp. When a 1st AC sets the lens barrel to $H$, everything from H ÷ 2 to ∞ is in focus. If you set the lens barrel directly to $\infty$, you waste half of your foreground depth of field!

• F-Stop ($f/N$): The mathematical ratio of focal length to entrance pupil diameter ($N = f / D_{\text{pupil}}$). F-stop governs physical Depth of Field.
• T-Stop (Transmission Stop): Measures actual light transmitted through the glass elements to the sensor (accounting for internal reflections and glass absorption). Cinema primes are calibrated in T-stops so swapping from a 14-element zoom to a 6-element prime at T2.8 yields identical exposure.

Every cinema lens projects a circular image onto the sensor plane. For a lens to cover a sensor mode without dark corners (mechanical portalling or optical vignetting), the lens's Image Circle (Ø) must be equal to or larger than the active mode's Physical Diagonal (Ø). For example, Cooke Mini S4/i primes (Ø 33.5mm) easily cover Canon C80/C400 S35 Crop (Ø 29.6mm) and ARRI ALEXA Mini 3.2K (Ø 30.3mm), while Full Frame Open Gate (Ø 43.3mm) requires Full-Frame/VV glass like Cooke SP3 (Ø 43.3mm) or DZOFilm Arles (Ø 46.5mm).

Perspective (the relative size of foreground to background objects) is determined 100% by camera-to-subject distance, not by focal length. If you keep the camera in the exact same spot on the dolly track and swap from a 50mm on Full Frame to a 35mm on Super 35, perspective, background compression, and actor geometry are 100% identical.

Calculated DoF tables assume standard viewing conditions. On set, a seasoned 1st AC mentally treats the usable focus zone as 30%–40% narrower than calculated when:
• Shooting on high-acuity 6K/8K sensors viewed on 4K OLED monitors.
• Pulling focus on high-contrast specular highlights (catchlights in an actor's eyes, wet skin, or practical bulbs), which reveal defocus blur immediately.
• Using vintage or high-speed lenses wide open (T1.3–T1.5), where spherical aberration and focus breathing shift the apparent plane of sharpest focus.

Front-anamorphic lenses use cylindrical glass elements that squeeze the horizontal axis by $1.33\times$, $1.5\times$, or $2.0\times$ while leaving the vertical axis spherical. This creates two distinct optical behaviors on set:
• Vertical Oval Bokeh & Dual DoF: Out-of-focus highlights stretch vertically by the squeeze factor, and the horizontal axis has a wider angle of view (deeper horizontal DoF) while the vertical axis has a longer effective focal length (shallower vertical DoF).
• Close-Focus Breathing & Diopters: Traditional variable-diopter anamorphics lose squeeze ratio at close focus ("anamorphic mumps"). Mounting a positive +1/2 or +1 diopter in the matte box lets you keep the anamorphic lens barrel near infinity where its squeeze ratio and astigmatism are sharpest!

Suppose Camera A is a Canon EOS C80 (Full Frame) with a 50mm @ T4.0, and Camera B is an ARRI ALEXA Mini (S35) with a 35mm @ T2.8 to match both Field of View and Depth of Field. Because Camera B's lens is opened 1 full stop wider (T2.8 vs T4.0) to match background blur, you must either engage 1 stop (0.3) of internal ND on Camera B or lower its EI/ISO by 1 stop so both cameras match exposure!

• Sensor Windowing (ARRI RAW, RED Komodo, Blackmagic BRAW): When shooting RAW, every pixel maps 1:1 to a physical photosite. Dropping resolution from 6K to 4K or 2K physically windows (crops) the center of the sensor, narrowing your Field of View.
• Full-Width Oversampling (Canon EOS C80 / C400 / C50, Sony FX6 / FX3): When you select Full Frame 4K DCI or 2K on a Canon C80 or C400, the camera reads the entire 6K Full-Frame width (36.0mm) and downsamples it internally. Your Field of View does not crop unless you explicitly switch the Sensor Mode menu to Super 35mm (Crop) or Super 16mm (Crop).

On the Canon EOS C80 and EOS C400, the native sensor array is 17:9 DCI (6000 × 3164 pixels = 36.0 × 19.0 mm). Switching from 4K DCI (4096×2160) to 4K UHD (3840×2160) keeps the full 19.0mm vertical height and trims the left/right edges to 33.8 × 19.0 mm (a 1.06x horizontal crop).

Although the Canon EOS C80 and EOS C400 share the same 6K Full-Frame BSI Stacked CMOS sensor, the EOS C400 includes a dedicated 2K Super 16mm (Crop) mode (13.1 × 6.9 mm), whereas the EOS C80 features Full-Frame and Super 35mm (Crop) modes only (no dedicated S16 crop mode).