ImageReasonSensor and Lens Resolution
Is my detail target inside the ideal diffraction and sampling limits?
Enter an image-plane spatial-frequency target and compare it with the ideal diffraction cutoff and sensor sampling Nyquist frequency, kept explicitly separate from a measured lens result.
Answer
Want to learn more? Sensors, Diffraction, Sampling, and Resolution
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Calculate to see the frequency axis (ideal limits, not measured MTF).
| Quantity | Value |
|---|
| Aperture | Diffraction cutoff |
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Calculate a result to generate a copyable plan.
A common plane for comparing limits
Resolution targets need a common plane. This planner works in line pairs per millimetre at the image plane, where an optical diffraction cutoff and a sensor sampling limit can be compared. It does not turn a distant bird feather, a document character, or a landscape branch into a number automatically. That conversion needs subject size, distance, magnification, projection, and output assumptions that belong in a different model.
The diffraction cutoff is calculated from wavelength and f-number. The sampling cutoff is calculated from pixel pitch. The lower of the two is a conservative ideal envelope for the simplified comparison. If your target exceeds that lower limit, at least one entered ideal constraint is below the target. If it is inside both limits, that does not prove the lens resolves it. Focus, motion, aberrations, subject contrast, color filtering, demosaicing, processing, and crop can reduce practical detail.
At 550 nm and f/8, the ideal diffraction cutoff is about 227 lp/mm. A 6 um pixel pitch has a sampling Nyquist frequency of about 83.3 lp/mm. For a 50 lp/mm target, the sampling figure is the lower ideal constraint but the target is inside both. That is a reason to test a real system, not a reason to label it sufficient.
Use this page when you have a stated image-plane requirement from a controlled reproduction, technical chart, or careful system test. Use the diffraction planner when the decision is which aperture to choose for depth and output. Use the MTF interpreter when you have properly documented measured information. Keeping these jobs separate prevents an ideal physics number from becoming an unsupported camera ranking.
FAQ
- Does an ideal cutoff prove my lens resolves that detail?
- No. It is one ideal constraint. Real lens, focus, motion, processing, and contrast can reduce detail.
- Can I enter subject detail in millimetres?
- Not on this page. It needs an explicit reproduction model to become image-plane spatial frequency.
- Why is the lower cutoff used?
- Both diffraction and sampling must support the target in this simplified comparison, so the lower ideal limit is the tighter condition.