Field of View Calculator - Camera FOV Calculator for Lenses | Free Tool

Field of View Calculator for Camera Lenses - FOV Calculator

Calculate camera field of view with our comprehensive FOV calculator. This field of view calculator supports multiple projection models including rectilinear and fisheye lenses, providing coverage predictions for machine vision, robotics, and imaging applications. Used by thousands of engineers for camera field of view calculations and optical system design.

Rectilinear Standard Projection
4+ Models Fisheye Projection
Free Tool No Registration

Camera Field of View Calculator

Calculate camera field of view using our interactive FOV calculator. Enter your lens focal length and sensor dimensions to determine horizontal, vertical, and diagonal field of view angles. This field of view calculator provides theoretical FOV based on standard optical formulas, with options for different lens projection models.

How to Use This FOV Calculator:

  1. Sensor Dimensions: Enter your camera sensor's active area width and height in millimeters
  2. Focal Length: Input the lens effective focal length (EFL) - not back focal length
  3. Projection Model: Select rectilinear for standard lenses, or appropriate fisheye model for wide-angle
  4. Calculate: View results for horizontal, vertical, and diagonal field of view
Important: This FOV calculator uses idealized optical models. Real lenses exhibit distortion, vignetting, and other aberrations that affect actual field of view. Results should be considered theoretical baselines for system design. Consult lens datasheets for measured FOV specifications.

Understanding This Field of View Calculator

Our field of view calculator implements standard optical formulas used in camera system design. The calculator provides theoretical FOV values based on geometric optics principles:

Calculation Methods by Lens Type:
  • Rectilinear Projection: FOV = 2 × arctan(d / 2f) where d = sensor dimension, f = focal length
  • Equidistant Fisheye: Image height = f × θ (angle in radians)
  • Stereographic Fisheye: Image height = 2f × tan(θ/2)
  • Orthographic Fisheye: Image height = f × sin(θ)
  • Equisolid Angle: Image height = 2f × sin(θ/2)

Key Considerations for Camera FOV:

Sensor Active Area: Use actual active dimensions, not total chip size
Effective Focal Length: EFL determines FOV, not back focal length
Image Circle: Lens must cover sensor diagonal to avoid vignetting
Aspect Ratio: Affects relationship between H/V/D FOV values
Real-World Variations: Actual camera field of view may differ from calculated values due to: lens distortion (typically 1-5% for standard lenses), manufacturing tolerances (±2-3%), temperature effects on focal length, and optical design variations. Always verify with manufacturer specifications for critical applications.
FOV Calculation Guide Browse M12 Lenses

How Does a Field of View Calculator Work?

A field of view calculator determines the angular extent of a scene captured by a camera system. The calculation depends fundamentally on the relationship between sensor size and lens focal length, but the specific formula varies based on lens projection type.

Rectilinear Lens FOV Formula
FOV = 2 × arctan d 2f
FOV:
Field of view angle in degrees
d:
Sensor dimension (width, height, or diagonal)
f:
Effective focal length of the lens
Valid only for rectilinear (non-fisheye) lenses with minimal distortion

This formula assumes an ideal pinhole camera model. Real lenses deviate from this model due to:

  • Lens distortion: Barrel distortion increases edge FOV; pincushion reduces it
  • Entrance pupil position: Affects the center of projection for angle calculations
  • Vignetting: Mechanical or optical vignetting limits usable FOV
  • Principal point offset: Shifts the optical axis from sensor center

Why Do Different Projection Models Matter for Camera FOV?

Camera field of view calculations change dramatically based on lens projection type. While rectilinear lenses maintain straight lines (at the cost of limiting FOV to less than 180°), fisheye lenses use alternative mathematical mappings to achieve wider coverage:

R Rectilinear Projection

  • Maintains straight lines in scene
  • FOV limited to <180° theoretically
  • Image height = f × tan(θ)
  • Standard for most photography
  • Increasing distortion toward edges at wide angles

F Fisheye Projections

  • Curves straight lines (except through center)
  • Can achieve 180° or greater FOV
  • Multiple projection models available
  • More uniform angular resolution
  • Used in surveillance, robotics, VR capture

How Do Fisheye Projections Affect the FOV Calculator?

Fisheye lenses require different formulas in the field of view calculator because they intentionally deviate from rectilinear projection to achieve wider coverage:

Fisheye Projection Types

  • Equidistant (f-theta): r = f × θ - Linear angle-to-radius mapping, common in measurement applications
  • Stereographic: r = 2f × tan(θ/2) - Preserves angles locally (conformal mapping)
  • Orthographic: r = f × sin(θ) - Provides orthographic view, compresses edges severely
  • Equisolid Angle: r = 2f × sin(θ/2) - Preserves solid angles, common in scientific imaging

Each projection affects how scene angles map to image positions, changing the effective FOV distribution across the sensor.

What Sensor Parameters Does the FOV Calculator Need?

Understanding Sensor Dimensions for Camera Field of View

Accurate field of view calculator results require precise sensor dimensions. Common confusion arises from:

  • Format designations vs. actual size: A "1/2.3-inch" sensor has ~6.17mm width, not 12.7mm
  • Active area vs. total size: Use only the photosensitive region dimensions
  • Aspect ratio variations: 4:3, 16:9, and 1:1 sensors with same diagonal have different H/V FOV

Common Sensor Formats for FOV Calculations

The field of view calculator requires accurate sensor dimensions. For comprehensive sensor format information and detailed specifications, visit our complete CMOS sensor size guide.

Camera sensor size comparison chart for FOV calculator reference
View Complete Sensor Guide Download PDF Reference

Note on Format Names: Historical "inch" designations (like 1/2.3") derive from video tube standards and don't equal physical measurements. Always verify actual sensor dimensions in manufacturer datasheets for accurate FOV calculator results.

OpenCV Distortion Models for FOV Correction

The OpenCV calibration framework uses a different distortion model than simple radial correction factors. OpenCV implements the Brown-Conrady model with polynomial coefficients that must be determined through calibration:

OpenCV Distortion Coefficients
Distortion = [k₁, k₂, p₁, p₂, k₃]
k₁, k₂, k₃:
Radial distortion coefficients
p₁, p₂:
Tangential distortion coefficients
Higher-order terms (k₄, k₅, k₆) available for severe distortion

Unlike simplified FOV calculators that apply uniform correction, OpenCV's model accounts for both radial and tangential distortion components. To obtain accurate distortion coefficients for your lens:

  • Use cv2.calibrateCamera() with checkerboard images captured at multiple positions
  • For wide-angle lenses (>120° FOV), use the cv2.fisheye module instead
  • Consider calibration tools like CamCalib for GUI-based coefficient extraction
  • Typical workflow: capture 20-30 calibration images → detect corners → optimize intrinsics

⚠️ OpenCV Fisheye vs Standard Model

OpenCV provides two distinct calibration models: the standard pinhole model (suitable for FOV < 120°) and the fisheye model (Kannala-Brandt) for wide-angle lenses. Using the wrong model will produce incorrect undistortion results. The fisheye model uses different distortion coefficients (θ-based rather than r-based) that better represent wide-angle projection.

Learn more about OpenCV camera calibration and distortion models in the OpenCV Camera Calibration documentation.

How Does Working Distance Relate to Camera FOV?

While the field of view calculator provides angular FOV, many applications need linear field dimensions at a specific working distance:

Linear Field of View Formula
Linear FOV = 2 × WD × tan Angular FOV 2
Linear FOV:
Scene width/height at working distance
WD:
Working distance from lens entrance pupil
Angular FOV:
Field of view angle from calculator
Assumes rectilinear projection; fisheye lenses require projection-specific formulas
🤖

Robot Navigation

  • Typical FOV: 120-180° horizontal
  • Sensor: 1/2.3" format typical
  • Lens: 1.8-2.8mm fisheye
  • Coverage at 2m: 6-12m width
🏭

Machine Inspection

  • Typical FOV: 20-40° diagonal
  • Sensor: 1" or larger
  • Lens: 16-35mm rectilinear
  • Working distance: 300-500mm
📹

Security Surveillance

  • Typical FOV: 80-110° horizontal
  • Sensor: 1/2.8" common
  • Lens: 2.8-4mm varifocal
  • Coverage: Full room width

What Are Common FOV Calculator Mistakes to Avoid?

Using Back Focal Length Instead of Effective Focal Length

The field of view calculator requires effective focal length (EFL), not back focal length (BFL). BFL measures the distance from the rear lens element to the sensor, while EFL determines the magnification and thus the camera field of view. These can differ significantly in complex lens designs. For help determining your lens's EFL, use our EFL calculator tool.

Ignoring Lens Distortion Impact on Actual FOV

Basic FOV calculator formulas assume zero distortion. Real lenses exhibit:

  • Barrel distortion: Common in wide-angle lenses, increases edge FOV by 5-20%
  • Pincushion distortion: Found in telephoto lenses, reduces edge FOV slightly
  • Complex distortion: Many lenses show "mustache" distortion mixing both types

⚠️ Critical for Wide-Angle Lenses

Wide-angle lenses (especially those approaching 180° FOV) cannot maintain rectilinear projection. The FOV calculator must use appropriate fisheye formulas for these lenses. Attempting to use the standard rectilinear formula will give incorrect results as focal length approaches zero.

Confusing Diagonal vs. Horizontal FOV Specifications

Manufacturers may specify field of view as horizontal, vertical, or diagonal. The FOV calculator computes all three, but be aware:

  • Security cameras often quote horizontal FOV
  • Photography lenses typically use diagonal FOV
  • Machine vision may specify both H and V separately
  • Fisheye lenses might give circular FOV (if not cropped)

How Do I Validate FOV Calculator Results?

To verify your field of view calculator results:

  1. Check manufacturer specifications: Compare calculated FOV with datasheet values
  2. Account for distortion: Published FOV may include distortion effects
  3. Verify sensor dimensions: Confirm you're using active area, not chip size
  4. Consider image circle: Ensure lens covers full sensor for claimed FOV
  5. Test empirically: Measure actual FOV using calibration targets when possible

Practical Validation Method

Place a measured target at known distance. Capture an image and measure how much of the target width/height appears in frame. Calculate actual FOV using:

Actual FOV = 2 × arctan(target_size / (2 × distance))

Compare with the FOV calculator prediction to identify any systematic differences.

Field of View Calculator FAQ

How accurate is this field of view calculator?
This FOV calculator provides theoretical values based on standard optical formulas. Results assume ideal lens behavior without distortion. Real lenses may vary due to distortion (typically 1-5%), manufacturing tolerances (±2-3%), and design variations. For critical applications, verify calculations against manufacturer specifications or empirical measurements.
Can I use this FOV calculator for fisheye lenses?
Yes, the field of view calculator includes multiple fisheye projection models (equidistant, stereographic, orthographic, equisolid). Select the appropriate projection type for your lens. Note that fisheye FOV represents maximum capture angle, but the image will show characteristic barrel distortion rather than rectilinear projection.
Why does my camera show different FOV than calculated?
Several factors can cause differences: (1) Lens distortion not accounted for in basic calculations, (2) Using sensor format size instead of actual active area, (3) Digital crop or binning reducing effective sensor size, (4) Confusion between horizontal, vertical, and diagonal FOV specifications, (5) Focus breathing changing effective focal length. Verify all input parameters and consider these factors.
What's the difference between EFL and BFL for FOV calculations?
Effective Focal Length (EFL) determines magnification and field of view - use this in the FOV calculator. Back Focal Length (BFL) is the physical distance from rear lens element to sensor, used for mechanical design. In simple lenses they're similar, but in complex designs (especially retrofocus wide-angle or telephoto) they differ significantly. Always use EFL for FOV calculations. Use our EFL calculator to determine effective focal length from lens specifications.
How do I measure actual FOV to verify calculations?
To empirically measure camera field of view: (1) Place a ruler or calibration target perpendicular to the optical axis at a known distance, (2) Capture an image and measure how much of the target appears in frame, (3) Calculate: FOV = 2 × arctan(visible_target_size / (2 × distance)). This gives you actual system FOV including all lens effects. Compare with calculator predictions to understand your system's characteristics.
Can this calculator handle anamorphic or specialty lenses?
This FOV calculator assumes symmetric lenses with equal horizontal and vertical magnification. Anamorphic lenses (with different H/V squeeze factors) require separate calculations for each axis. For specialty lenses like tilt-shift, telecentric, or pericentric designs, consult manufacturer specifications as standard FOV formulas may not apply.