Lens Equivalence Comparator

Format match

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Check the lens setup

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Setup preset:

Start from APS-C, Micro Four Thirds, Super 35, full-frame, medium-format, or compact-camera examples.

Source format:

Pick the body or crop mode you want to match from.

Source custom sensor:

Use the active image area after still/video mode crops.

x mm

Target format:

Target focal length and depth-of-field look are calculated for this format.

Target custom sensor:

Use the target active image area after still/video mode crops.

x mm

Source focal length:

This value is the physical lens marking on the source camera.

Source aperture:

Equivalent aperture is a depth-of-field look comparison; it is not an exposure multiplier.

Source extra crop:

Leave at 1.0 for stills, open-gate, or uncropped video.

Target extra crop:

Set the target crop if you are matching a video mode, stabilizer crop, or open-gate extraction.

Target lens set:

Choose the common focal-length list closest to the target kit you are planning around.

Close-match tolerance: {{ formatPlainNumber(match_tolerance_percent, 0) }}%

A smaller value is stricter about whether a real lens is close to the exact target focal length.

Metric	Value	Detail	Copy
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Format item	Source	Target	Note	Copy
{{ row.item }}	{{ row.source }}	{{ row.target }}	{{ row.note }}

Target lens	Frame read	Aperture target	Match status	Use cue	Copy
{{ row.target_lens }}	{{ row.frame_read }}	{{ row.aperture_target }}	{{ row.match_status }}	{{ row.use_cue }}

Chart renderer unavailable; use the Lens Match Table and Format Ledger for the same equivalence data.

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The number printed on a lens does not change when the lens is mounted on a different camera, but the recorded frame can change a great deal. A 35 mm lens remains a 35 mm lens on full frame, APS-C, Micro Four Thirds, Super 35, medium format, or a cropped video mode. The difference is the active image area behind the lens: a smaller sensor or recording crop captures a smaller rectangle from the projected image circle, so the same physical lens records a tighter view.

Lens equivalence is a translation problem. It asks what focal length on the target format gives similar framing, then asks what f-number gives a similar depth-of-field look after the framing is matched. Those answers help when replacing a lens after changing systems, matching A and B cameras, planning a prime set, or checking whether a stabilizer or 4K crop will turn a wide shot into a normal-looking one.

Physical focal length: The lens marking in millimeters. It is an optical property of the lens, not a format-adjusted label.
Active image area: The width and height actually recorded, after still-photo format, video mode, stabilization, or extraction crops.
Crop factor: A ratio based on the active image diagonal compared with the 36 x 24 mm full-frame reference.
Equivalent aperture: An f-number used to compare depth-of-field appearance across matched framing, not a new exposure value.

Two sensor rectangles connected by a lens scaling arrow for format equivalence

Full-frame equivalence is common because 35 mm film and 36 x 24 mm digital sensors became the shared reference point. The convention makes compact cameras, APS-C mirrorless bodies, cinema crops, and medium-format stills bodies easier to compare, but it can hide the real purchase or rental question. For a shot list, the useful answer is usually the target physical lens: the number printed on the lens you would actually mount.

Depth-of-field equivalence is the part most easily misread. If a 35 mm f/1.8 lens on APS-C matches the framing and blur impression of roughly 54 mm at about f/2.8 on full frame, the APS-C lens still meters as f/1.8. Setting the full-frame lens to f/2.8 gives the comparable look, but it also changes exposure in the ordinary way because the target aperture has actually been stopped down.

Equivalence does not make perspective, lens rendering, focus breathing, T-stop transmission, close-focus behavior, aspect-ratio coverage, or bokeh shape identical. Perspective follows camera position, and blur character follows the optical design as well as the f-number. Treat equivalence as a planning guide for framing and depth-of-field appearance, then test the actual lens and camera mode when a shot depends on exact coverage.

How to Use This Tool:

Start from the lens and camera setup you already understand, then translate that setup to the target format you want to shoot.

Choose a Setup preset that is close to your situation, such as APS-C to full frame, Micro Four Thirds to full frame, Super 35 cinema to full frame, full frame to Micro Four Thirds, 44 x 33 medium format to full frame, or a compact-camera example.
Set Source format to the camera or recording format where the known lens is used. Select Custom sensor only when you know the active width and height in millimeters.
Set Target format to the camera, crop mode, or active image area you want to match. For custom targets, enter the target active dimensions after any mode crop.
Enter Source focal length as the physical lens marking and Source aperture as the f-number selected on that lens. Do not enter a full-frame equivalent value in the focal-length field.
Use Source extra crop and Target extra crop for video crops, digital stabilization, open-gate extractions, or any mode that records less than the selected format. Leave the value at 1.00x when there is no additional crop.
Pick the Target lens set closest to the kit you are comparing against. Use Close-match tolerance to decide how strict the Lens Match Table should be when it labels candidate focal lengths.
Read the summary, then check Match Brief for target focal length and depth-of-field look, Format Ledger for crop factors and active dimensions, Lens Match Table for practical substitutes, and Format Match Map for a cross-format chart.

If Check the lens setup appears, fix the input before trusting the numbers. The usual corrections are a source focal length above 0 mm, a source aperture of f/0.7 or slower, positive custom sensor dimensions, and extra crop values of 1.00x or greater.

Interpreting Results:

Target focal length is the main planning number. It is the physical focal length to look for on the target format. If the result is 53.7 mm on full frame, a 50 mm lens is slightly wider and a 56 mm lens is slightly tighter; neither lens becomes the exact calculated value.

Depth-of-field look describes the f-number that gives a similar blur comparison after the framing has been matched. Read it beside Exposure note, because using that f-number on the target lens changes brightness according to normal exposure rules. Equivalent aperture is a look comparison, not a command to remeter the source setup.

The Lens Match Table compares real focal lengths against the exact target focal length. With the default 8% tolerance, Close match means the candidate is within 8%, Practical substitute means it is outside that tolerance but no more than 20% away, and Different framing means the lens should be treated as a composition change.

A clean result can still be misleading when the active area is wrong. Before choosing a lens, verify Active sensor, Diagonal crop factor, and Extra crop in Format Ledger, especially for video modes and stabilized recordings. Then confirm the suggested aperture is available on the target lens if depth-of-field match matters.

Technical Details:

Format equivalence starts with geometry. A lens projects an image circle, and the camera records a rectangle from that projection. The diagonal of that recorded rectangle is a compact way to compare common formats because it accounts for both width and height. A smaller diagonal raises crop factor; a larger diagonal lowers it.

The full-frame reference used here is 36 x 24 mm, whose diagonal is about 43.27 mm. The source-to-target scale is not a separate photographic property; it is the ratio between two effective crop factors. The same scale gives the target focal length for similar framing and the f-number for a similar depth-of-field look, while exposure remains tied to the actual aperture set on the lens.

Formula Core

The active image diagonal comes from the recorded width and height:

d = \sqrt{w^{2} + h^{2}}

Effective crop factor compares that diagonal with full frame and then applies any extra recording crop:

C = \frac{43.27 mm}{d} \times E

The source-to-target scale is the source effective crop factor divided by the target effective crop factor:

R = \frac{C_{source}}{C_{target}}

Target focal length and the depth-of-field equivalent f-number use that scale:

F_{target} = F_{source} \times R N_{look} = N_{source} \times R

When the matched-look f-number is compared with the source f-number, the exposure difference follows the usual two-stop-per-doubling f-number relationship:

stops = 2 \times \log_{2} (\frac{N_{look}}{N_{source}})

Lens equivalence formula symbols
Symbol	Meaning	Where it appears
w, h	Active image width and height in millimeters.	Selected format dimensions or custom sensor dimensions.
E	Extra crop from a recording mode, stabilizer, or extraction.	Source extra crop and Target extra crop.
C	Effective diagonal crop factor after extra crop.	Diagonal crop factor in Format Ledger.
R	Source-to-target scale used for matching.	Match multiplier in Format Ledger.
F	Physical focal length in millimeters.	Source focal length and Target focal length.
N	F-number used for aperture and depth-of-field comparison.	Source aperture, Depth-of-field look, and Exposure note.

Format Reference

Built-in formats use common active-frame dimensions. Custom entries are useful when a camera records a different active area from its still-photo format, or when a production note gives a precise crop.

Built-in camera format dimensions and approximate crop factors
Format	Active size	Approx. crop factor	Common context
44 x 33 medium format	44.0 x 33.0 mm	0.79x	Larger-than-full-frame stills reference.
Full frame / 35mm	36.0 x 24.0 mm	1.00x	Shared comparison baseline.
APS-H 1.3x	28.7 x 19.1 mm	1.25x	Legacy crop and specialty stills reference.
APS-C 1.5x	23.5 x 15.6 mm	1.53x	Many Nikon, Sony, Fujifilm, Pentax, and similar APS-C bodies.
Canon APS-C 1.6x	22.3 x 14.9 mm	1.61x	Canon crop-sensor stills bodies.
Super 35 cinema	24.9 x 18.7 mm	1.39x	Cinema-style framing reference.
Micro Four Thirds	17.3 x 13.0 mm	2.00x	Mirrorless stills and compact video setups.
1-inch type	13.2 x 8.8 mm	2.73x	Compact cameras and small video cameras.
2/3-inch video	8.8 x 6.6 mm	3.93x	Broadcast-style video formats.

Candidate Lens Rules

Candidate lenses are judged by their percentage difference from the exact target focal length. A candidate that is close in millimeters can still read as wider or tighter in the frame, so the status label should be read with the frame-read cue.

Candidate lens match status boundaries
Match status	Boundary	How to read it
Close match	Difference <= tolerance	Use first when the listed wider or tighter frame read is acceptable.
Practical substitute	Tolerance < difference <= 2.5 x tolerance	Works when you can crop, step back, move closer, or accept a changed frame.
Different framing	Difference > 2.5 x tolerance	Use as a different composition rather than a direct equivalent.

Validation Bounds

Accepted lens equivalence input bounds
Input	Accepted range	Why it matters
Source focal length	Greater than 0 mm.	A zero or missing focal length makes the framing scale meaningless.
Source aperture	f/0.7 or slower.	The depth-of-field comparison needs a positive, plausible f-number.
Custom sensor dimensions	Positive width and height, with controls intended for 1 mm to 80 mm.	Crop factor depends on a real active diagonal.
Extra crop	1.00x or greater.	Extra crop reduces active area; values below 1.00x would imply expansion beyond the selected format.

Worked Mechanism Path

A 35 mm f/1.8 source lens on 23.5 x 15.6 mm APS-C has a diagonal near 28.21 mm. Dividing the 43.27 mm full-frame diagonal by 28.21 mm gives an effective crop factor near 1.53x when no extra crop is added. Matching that setup to full frame uses a scale of 1.53, so the target focal length is 35 x 1.53 = 53.7 mm and the depth-of-field look is f/1.8 x 1.53 = f/2.8. The APS-C lens still exposes at f/1.8, while a full-frame lens set to f/2.8 exposes as f/2.8.

Accuracy and Privacy Notes:

Lens equivalence is deterministic geometry, but visual similarity is broader than geometry. The comparison does not model exact lens rendering, focus breathing, T-stop transmission, adapter optics, macro pupil magnification, changing stabilization crops, or the way different aspect ratios alter horizontal and vertical framing.

Use active recording dimensions when a stills body, video mode, or stabilizer crop records less than the named format.
Keep subject distance and camera position in mind; changing position changes perspective even when framing looks similar.
Depth-of-field look assumes similar framing and focus distance. Close-up and macro work can depart from the simple crop-factor comparison.
No image, EXIF file, or camera file is uploaded. Entered lens and sensor values are used in the browser to calculate the tables, JSON, and chart.

Worked Examples:

APS-C portrait moved to full frame. With APS-C 1.5x as the source, Full frame / 35mm as the target, 35 mm as Source focal length, f/1.8 as Source aperture, and both extra crops at 1.00x, Target focal length reads about 53.7 mm. Depth-of-field look reads about f/2.8, so a 50 mm or 56 mm target lens can be close depending on the desired frame.

Micro Four Thirds video with a source crop. A 12 mm f/2.8 lens on Micro Four Thirds normally frames like about 24 mm on full frame. If the recording mode adds a 1.25x Source extra crop, Format Ledger shows a larger effective source crop factor, and Target focal length moves to about 30.0 mm. Depth-of-field look moves to about f/7.0, but the original lens is still metered at f/2.8.

Full-frame portrait matched on Micro Four Thirds. An 85 mm f/1.8 source on full frame maps to about 42.5 mm on Micro Four Thirds and about f/0.9 for matched depth-of-field appearance. With the default tolerance, a 40 mm lens can be a Close match, while a 50 mm lens is usually a Practical substitute. If f/0.9 is not available, the framing can still be matched, but the target setup will show deeper depth of field.

Custom setup recovery. If a custom sensor width is cleared or the source focal length is set to 0, Check the lens setup appears before the comparison should be used. Enter positive custom dimensions and a source focal length greater than 0 mm, then recheck Active sensor, Diagonal crop factor, and Target focal length.

FAQ:

Should I enter the lens marking or the equivalent focal length?

Enter the physical lens marking in Source focal length. A 35 mm APS-C lens should be entered as 35 mm, not as its full-frame equivalent, because the comparison applies the crop factor.

Does equivalent aperture change exposure?

No. Depth-of-field look compares blur appearance after matching framing. Exposure is still based on the actual f-number set on the lens, which is why Exposure note keeps metering separate.

How should video crop modes be handled?

Use Source extra crop or Target extra crop when a video mode, digital stabilizer, or extraction uses less than the selected format. Active sensor and Diagonal crop factor show the effect.

What does Close match mean?

Close match means the target lens candidate is within the current Close-match tolerance of the exact target focal length. Raising the tolerance makes the label more forgiving; lowering it makes the label stricter.

Why might the Format Match Map be unavailable?

The chart can be unavailable when the chart renderer cannot draw or when the setup has validation errors. Use Match Brief, Format Ledger, and Lens Match Table for the same comparison data, then fix any alert values before checking the chart again.

Does the comparison upload my lens or camera data?

No image, EXIF file, or camera file is uploaded. The focal length, aperture, sensor dimensions, crop settings, and tolerance are used in the browser to calculate the visible results.

Glossary:

Active image area: The recorded sensor or crop area used for the comparison, measured by width and height.
Crop factor: The ratio between the full-frame diagonal and the active image diagonal, after extra crop is applied.
35 mm equivalent focal length: The focal length on a 35 mm film or full-frame camera that gives a similar angle of view.
Equivalent aperture: The f-number used to compare depth-of-field look across matched framing, separate from exposure metering.
Extra crop: An additional reduction in active recording area from video mode, stabilization, or extraction.
F-number: The focal length divided by the effective aperture diameter, written as values such as f/1.8 or f/2.8.
Image circle: The circle of light projected by a lens, from which the active image area records a rectangle.

References:

CIPA DCG-X002-Translation-2015: Specification Guideline for Digital Cameras, Camera & Imaging Products Association, 2015.
The DX and FX Formats, Nikon Imaging USA.
D850 Image Area, Nikon Corporation.
Aperture, f-numbers and depth of field, Sony.
Understanding Depth of Field in Photography, Cambridge in Colour.