Starlight Notes

FE Lens Diffraction Comparison

Compare telephoto reach, teleconverters and Super 35 crops, and see how aperture relates to a chosen diffraction criterion.

Published

Reach · aperture · diffraction

Compare your telephoto options

Camera presets are approximate pixel-scale estimates. The Airy criterion is a comparison reference, not a hard sharpness cutoff. Read the assumptions ↓

Lenses
Teleconverters and crop mode

Original is always included. S35 uses a 1.5× crop; combinations are theoretical, without a compatibility check.

Filtering keeps the first TC tier above the criterion, then hides stronger tiers. If the original already exceeds it, all TC tiers are hidden. S35 follows its TC tier.

≈ f/8.75Physical aperture at the selected 2-pixel Airy criterion · 33 configurations.
Reach versus aperture
Telephoto reach and aperture comparisonCircles show full frame; squares show Super 35. Hollow points exceed the selected Airy criterion. Hover, click or focus a point to show its origin and values below the graph.0340680102013601700f/2.8f/4f/5.6f/8f/11f/16Full-frame-equivalent focal length / field of view (mm)Full-frame-equivalent f-number · full-stop spacingFull frame ≈ f/8.7570–200 mm f/2.8 · Original: 200 mm equivalent, physical f/2.8, equivalent f/2.8. At or below the selected Airy criterion.70–200 mm f/2.8 · 1.4× TC: 280 mm equivalent, physical f/3.92, equivalent f/3.92. At or below the selected Airy criterion.70–200 mm f/2.8 · 2× TC: 400 mm equivalent, physical f/5.6, equivalent f/5.6. At or below the selected Airy criterion.300 mm f/2.8 · Original: 300 mm equivalent, physical f/2.8, equivalent f/2.8. At or below the selected Airy criterion.300 mm f/2.8 · 1.4× TC: 420 mm equivalent, physical f/3.92, equivalent f/3.92. At or below the selected Airy criterion.300 mm f/2.8 · 2× TC: 600 mm equivalent, physical f/5.6, equivalent f/5.6. At or below the selected Airy criterion.400 mm f/2.8 · Original: 400 mm equivalent, physical f/2.8, equivalent f/2.8. At or below the selected Airy criterion.400 mm f/2.8 · 1.4× TC: 560 mm equivalent, physical f/3.92, equivalent f/3.92. At or below the selected Airy criterion.400 mm f/2.8 · 2× TC: 800 mm equivalent, physical f/5.6, equivalent f/5.6. At or below the selected Airy criterion.100–400 mm f/4.5 · Original: 400 mm equivalent, physical f/4.5, equivalent f/4.5. At or below the selected Airy criterion.100–400 mm f/4.5 · 1.4× TC: 560 mm equivalent, physical f/6.3, equivalent f/6.3. At or below the selected Airy criterion.100–400 mm f/4.5 · 2× TC: 800 mm equivalent, physical f/9, equivalent f/9. Above the selected Airy criterion.100–400 mm f/5.6 · Original: 400 mm equivalent, physical f/5.6, equivalent f/5.6. At or below the selected Airy criterion.100–400 mm f/5.6 · 1.4× TC: 560 mm equivalent, physical f/7.84, equivalent f/7.84. At or below the selected Airy criterion.100–400 mm f/5.6 · 2× TC: 800 mm equivalent, physical f/11.2, equivalent f/11.2. Above the selected Airy criterion.100–400 mm f/8 · Original: 400 mm equivalent, physical f/8, equivalent f/8. At or below the selected Airy criterion.100–400 mm f/8 · 1.4× TC: 560 mm equivalent, physical f/11.2, equivalent f/11.2. Above the selected Airy criterion.100–400 mm f/8 · 2× TC: 800 mm equivalent, physical f/16, equivalent f/16. Above the selected Airy criterion.600 mm f/4 · Original: 600 mm equivalent, physical f/4, equivalent f/4. At or below the selected Airy criterion.600 mm f/4 · 1.4× TC: 840 mm equivalent, physical f/5.6, equivalent f/5.6. At or below the selected Airy criterion.600 mm f/4 · 2× TC: 1200 mm equivalent, physical f/8, equivalent f/8. At or below the selected Airy criterion.200–600 mm f/6.3 · Original: 600 mm equivalent, physical f/6.3, equivalent f/6.3. At or below the selected Airy criterion.200–600 mm f/6.3 · 1.4× TC: 840 mm equivalent, physical f/8.82, equivalent f/8.82. Above the selected Airy criterion.200–600 mm f/6.3 · 2× TC: 1200 mm equivalent, physical f/12.6, equivalent f/12.6. Above the selected Airy criterion.400–800 mm f/8 · Original: 800 mm equivalent, physical f/8, equivalent f/8. At or below the selected Airy criterion.400–800 mm f/8 · 1.4× TC: 1120 mm equivalent, physical f/11.2, equivalent f/11.2. Above the selected Airy criterion.400–800 mm f/8 · 2× TC: 1600 mm equivalent, physical f/16, equivalent f/16. Above the selected Airy criterion.400 mm f/4.5 · Original: 400 mm equivalent, physical f/4.5, equivalent f/4.5. At or below the selected Airy criterion.400 mm f/4.5 · 1.4× TC: 560 mm equivalent, physical f/6.3, equivalent f/6.3. At or below the selected Airy criterion.400 mm f/4.5 · 2× TC: 800 mm equivalent, physical f/9, equivalent f/9. Above the selected Airy criterion.600 mm f/6.3 · Original: 600 mm equivalent, physical f/6.3, equivalent f/6.3. At or below the selected Airy criterion.600 mm f/6.3 · 1.4× TC: 840 mm equivalent, physical f/8.82, equivalent f/8.82. Above the selected Airy criterion.600 mm f/6.3 · 2× TC: 1200 mm equivalent, physical f/12.6, equivalent f/12.6. Above the selected Airy criterion.
Where this point comes from
Hover, click or keyboard-focus a point to see its lens, teleconverter and crop configuration. Overlapping points list every matching configuration.

● Full frame   ■ S35 crop   ·   Hollow points exceed the physical Airy criterion. Dashed lines mark the criterion; crop mode has a separate equivalent line. Hover, click or focus points for details.

70–200 mm f/2.8300 mm f/2.8400 mm f/2.8100–400 mm f/4.5100–400 mm f/5.6100–400 mm f/8600 mm f/4200–600 mm f/6.3400–800 mm f/8400 mm f/4.5600 mm f/6.3
Calculated results (33 configurations)
All values are theoretical estimates. Diffraction status uses physical aperture.
LensConfigurationOptical focal length (mm)Equivalent focal length (mm)Physical apertureEquivalent apertureAiry criterion
70–200 mm f/2.8Original200200f/2.8f/2.8At or below
70–200 mm f/2.81.4× TC280280f/3.92f/3.92At or below
70–200 mm f/2.82× TC400400f/5.6f/5.6At or below
300 mm f/2.8Original300300f/2.8f/2.8At or below
300 mm f/2.81.4× TC420420f/3.92f/3.92At or below
300 mm f/2.82× TC600600f/5.6f/5.6At or below
400 mm f/2.8Original400400f/2.8f/2.8At or below
400 mm f/2.81.4× TC560560f/3.92f/3.92At or below
400 mm f/2.82× TC800800f/5.6f/5.6At or below
100–400 mm f/4.5Original400400f/4.5f/4.5At or below
100–400 mm f/4.51.4× TC560560f/6.3f/6.3At or below
100–400 mm f/4.52× TC800800f/9f/9Above
100–400 mm f/5.6Original400400f/5.6f/5.6At or below
100–400 mm f/5.61.4× TC560560f/7.84f/7.84At or below
100–400 mm f/5.62× TC800800f/11.2f/11.2Above
100–400 mm f/8Original400400f/8f/8At or below
100–400 mm f/81.4× TC560560f/11.2f/11.2Above
100–400 mm f/82× TC800800f/16f/16Above
600 mm f/4Original600600f/4f/4At or below
600 mm f/41.4× TC840840f/5.6f/5.6At or below
600 mm f/42× TC12001200f/8f/8At or below
200–600 mm f/6.3Original600600f/6.3f/6.3At or below
200–600 mm f/6.31.4× TC840840f/8.82f/8.82Above
200–600 mm f/6.32× TC12001200f/12.6f/12.6Above
400–800 mm f/8Original800800f/8f/8At or below
400–800 mm f/81.4× TC11201120f/11.2f/11.2Above
400–800 mm f/82× TC16001600f/16f/16Above
400 mm f/4.5Original400400f/4.5f/4.5At or below
400 mm f/4.51.4× TC560560f/6.3f/6.3At or below
400 mm f/4.52× TC800800f/9f/9Above
600 mm f/6.3Original600600f/6.3f/6.3At or below
600 mm f/6.31.4× TC840840f/8.82f/8.82Above
600 mm f/6.32× TC12001200f/12.6f/12.6Above

Cropping changes framing and output equivalence. It does not change physical f-number or the Airy-disc size on the sensor.

Reading the comparison

Choose lenses, teleconverter configurations, a camera estimate and a wavelength. Original configurations stay visible whenever their lens is selected. Zoom lenses are evaluated at the listed long-end focal length. The three 100–400 mm entries represent different lenses, with the listed f-numbers used for their calculations at 400 mm.

The horizontal axis shows full-frame-equivalent focal length, which describes framing. A 600 mm lens with a 1.4× teleconverter has an optical focal length of 840 mm. A further 1.5× crop gives framing equivalent to 1260 mm on full frame; it does not turn the lens into an optical 1260 mm lens.

Switch the vertical axis between physical and equivalent aperture. With that same 600 mm f/4 lens, a 1.4× teleconverter gives physical f/5.6; with a 1.5× crop, the equivalent f-number becomes f/8.4. Exposure and the Airy-disc calculation still use physical f/5.6.

Circles indicate full-frame configurations; squares indicate S35 crops. Hollow markers exceed the selected physical Airy criterion. In equivalent-aperture view, the S35 criterion line is multiplied by 1.5, so crop points are compared on the same basis. The graph uses full-stop spacing vertically, with smaller f-numbers at the bottom. Hover, click or keyboard-focus a point to show its original lens, teleconverter/crop configuration and calculated values in the panel below the graph. Overlapping points list every matching configuration. The details stay visible until you inspect another point or change the comparison. Expand Calculated results for the complete table. Labels may overlap when many configurations are selected; clear lenses to inspect a smaller group.

The optional TC filter retains the first teleconverter tier above the criterion and hides stronger tiers. If the original aperture already exceeds the criterion, it hides every TC tier. Cropped configurations follow the same TC rule because cropping does not change the Airy-disc diameter at the sensor. This filter is a viewing aid, not a recommendation to use or avoid a particular teleconverter.

Sharing a comparison

Choose your settings, then click Copy link to these settings above the graph. Opening that link restores the camera, Airy-disc criterion, wavelength, selected lenses, teleconverters, crop modes, aperture display, point labels and TC filter. The link is also shown for manual copying if clipboard access is unavailable. Copied links use the public website address, so they can be shared with other people once the changes are published.

Copied links use one short settings code to reduce problems with forum link formatting. Paste the complete link into your post; a forum may shorten the visible text without changing the destination. The browser address updates as you change settings, so you can also bookmark your current comparison. Reset returns to the original comparison and updates the address accordingly.

Assumptions and camera presets

All results are estimates, not lens measurements. The camera selector supplies approximate reference f-numbers for an Airy-disc diameter of two pixels at 550 nm: f/8.75, f/7.62, f/6.18, f/5.56 and f/5.35, respectively. They are calculation presets, not manufacturer-specified diffraction limits or independently verified pixel pitches. The Sony A7R VI 67 MP preset uses the f/5.35 reference. For a two-pixel reference, the implied pixel pitch is 2.44 × 0.55 × reference f-number / 2 in micrometres.

S35 is modelled as a fixed 1.5× crop of the same sensor, retaining the same pixel pitch. It is not a simulation of a separate APS-C camera or a specific video readout. Real crop factors and resampling can differ. Teleconverters multiply optical focal length and physical f-number by 1.4 or 2; no extra transmission loss, aberrations or autofocus changes are modelled. Selecting a combination does not establish lens/teleconverter compatibility.

The equivalent f-number describes output equivalence at matched framing and output size; it is not the exposure f-number. Diffraction grows gradually. A two-, two-and-a-half- or three-pixel Airy diameter is a chosen reference, not a boundary between sharp and unusable images. Lens aberrations, focus, motion, demosaicing, processing and final viewing size all affect the result.

How diffraction is calculated

For an ideal circular aperture, the Airy-disc diameter between the first minima is approximately:

Airy diameter = 2.44 × wavelength × physical f-number

Use matching units for wavelength and diameter. This relation and its wavelength dependence are described by Edmund Optics. Here the calculation scales each two-pixel, 550 nm camera reference as follows:

Criterion f-number = reference f-number × (chosen pixel diameter / 2) × (550 / wavelength in nm)

For example, the f/8.75 preset becomes approximately f/6.88 at 700 nm with the same two-pixel criterion. This is the aperture at which the ideal Airy diameter reaches the selected pixel count. It does not predict measured lens resolution or how much extra subject detail a teleconverter will resolve.

For a geometric comparison of framing alone, use the Field of View Calculator.

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