Lens Scores

What do the scores mean?

Information about Scores

FoCal IQ provides a score for a set of attributes of a lens. Each score is the result of a group of measurements, and is a value between 0 (worst) and 100 (best).

The following sections give a brief explanation of the meaning of each score.

Note: You can quickly jump to the appropriate section from the details pages by clicking on the help icon .

Overall

The overall score is the average of all the other metric scores detailed below.

For zoom lenses, within the lens detail page there will be an overall score for the Wide and the Telephoto ends of the zoom range, but within the lens filter page the average of these two values will be used to create a single, overall lens score.

Calibration

The calibration information shows how well calibrated this lens is likely to be new, out of the box. A higher score (close to 100) indicates that you are less likely to need to calibrate the lens. The score takes into account the likely amount of calibration required, the variation in calibration across many lenses as well as the likely improvement between an uncalibrated and calibrated lens. For zoom lenses, we also use parfocality, which is a measure of the difference in calibration required between each end of the zoom range.

Focus

The focus information shows how consistent and accurate the focus is for this lens, measured across all camera bodies.

Performance

Performance is a composite score which averages the Wide and Peak scores.

The Performance value is not displayed in the table on a specific lens summary page (as the individual values for wide and peak performance are shown), but it is used for brevity in the complete Lens Database table.

Wide Performance

The wide information shows the performance of the lens when wide open. The measurements are comparisons with the values at the aperture of best image quality, and include measurements of quality, astigmatism and colour-specific quality.

Peak Performance

The peak information shows the performance of the lens at the aperture of best image quality.

Quality

Quality is a composite score which averages the Vignetting, Aberrations and Physical Quality scores.

The Quality value is not displayed in the table on a specific lens summary page (as the individual values for vignetting, aberrations and physical quality are shown), but it is used for brevity in the complete Lens Database table.

Vignetting

The vignetting information shows how the light is attenuated in the corners of the frame across the aperture range.

Aberrations

The aberrations information shows details of the astigmatism and colour quality changes across the aperture and focus range.

Physical Quality

The physical quality information combines consistency and quality metrics to indicate the overall physical (electrical, mechanical and optical) quality and consistency of the lens.