Lens Correction

Capture One has numerous tools to deal with lens distortion, including automatic detection and correction using lens profiles.

Overview of correction profiles

The Lens Correction tool includes predefined corrections or profiles for many popular lenses from major lens manufacturers. The profiles include corrections for distortion, chromatic aberration, diffraction, and both sharpness and light fall-off.

In addition to lens specific profiles, the Generic or Generic Pincushion Distortion profiles available in the Lens Correction tool address the most detrimental issues related to any simple spherical lens. Complex distortion however, can only be fully corrected with the lens specific profiles. Where possible the lens type will be automatically selected in the Profile menu. A selection of the most suitable lens correction profiles can be found under the Recommended Lenses heading, or you can manually select a lens correction profile from the available list.

If a specific lens model is not supported in the Lens Correction tool, you can create a Lens Cast Calibration (LCC) profile to correct a number of issues. For more details, see the section on Create a LCC profile.

Apply a specific lens profile

When Capture One detects a lens model with a correction profile in the database, the profile is selected and, typically, chromatic aberration and distortion correction adjustments are automatically applied.

If the lens model has not been detected, follow the steps below to locate the profile manually or to select a profile for a similar lens. To manually apply correction, follow the steps under the Apply a generic lens profile section, below.  

  1. Go to the Lens Tool Tab and select the Lens Correction tool.
  2. Select an image from the browser and choose a specific lens from the Profile drop down menu. (A selection of the most suitable lens correction profiles can be found under the Recommended Lenses heading or select one from the available list).
  3. Once a lens is selected, a check mark will appear in the Chromatic Aberration check-box and Capture One will automatically apply the correction based on the lens profile.
  4. If the image still shows some chromatic aberration, click the Analyze (...) button to the right to start Capture One's built-in analysis and correction algorithms. This will nearly always result in improved correction of chromatic aberration, as the adjustment is based on the actual lens (and image sensor) used during capture.
  5. Adjust the Distortion, Sharpness Falloff and Light Falloff sliders as necessary. Diffraction correction may also be necessary, see below for more details.

Apply a generic lens profile

When a lens is not recognized by Capture One, you can either select a profile for a similar lens from the list that will apply corrections automatically (see above), or correct the lens using the following steps.

  1. Go to the Lens Tool Tab and select the Lens Correction tool. 
  2. Select an image from the browser and choose the Generic option from the Profile drop down menu.  (All sliders in the tool are reset; there are no default settings for a generic lens).
  3. Check mark the option boxes, as desired 
  4. Select the Chromatic Aberration option to start chromatic aberration analysis and correction on the selected image. Multiple images can be corrected after selecting the Edit All Selected Variants option from the Edit menu or Toolbar.
  5. Click on the Analyze (…) button to restart the process, if necessary.
  6. Adjust the Distortion, Sharpness Falloff and Light Falloff sliders to the desired settings. See below for more details.

About chromatic aberration and purple fringing

Chromatic aberration occurs because light of different wavelengths takes different paths through the lens that may not be in focus on the sensor. As most light is a mix of several wavelengths, the lens will focus the colors differently and create color fringes on edges of high contrast areas.

Since chromatic aberration results from colors that have shifted, a white or light color on a dark background will have colors on either side. The most common effects are seen as red/cyan and blue/yellow fringes but others are possible. One of the more unsightly is green/purple but this should not be confused with purple fringing.

Steel, chrome and other metallic products often give rise to extreme contrast that can generate purple fringing. Purple fringing is, like chromatic aberration, an artifact that occurs because a lens interacts differently with light of varying wavelengths. Unlike chromatic aberration, purple fringing will not usually show fringes of different colors. Purple fringing is mostly visible on the edges of very high contrast image areas, such as metallic products or branches on a tree against a bright sky.

Purple fringing is often seen on images that also show chromatic aberration. Wide-angle lenses are more likely to show this artifact.

Removing chromatic aberration

Capture One’s chromatic aberration analysis function can be used to remove troublesome fringing from multiple images, not just single photos. This option will override chromatic aberration correction from a lens profile and, as each individual image itself is analyzed, often results in improved correction.

  1. Go to the Lens Tool Tab and select the Lens Correction tool.
  2. Select multiple images from the browser.
  3. Press the Analyze (…) button to start the correction process.

Removing purple fringing

Capture One features a specifically designed tool to remove purple fringing. It includes a familiar slider allowing control over the intensity, as well as the usual options to save the resulting setting to the adjustments clipboard or as a preset. Both allow the setting to be applied to multiple images. Although the Purple Fringing tool is offered as a standalone control for global corrections, purple fringing removal can also be applied locally, using an adjustments layer. As a result, the Purple Fringing tool can be found under both the Lens Tool Tab as well as the Local Adjustments Tool Tab.

  1. Go the Lens Tool Tab or Local Adjustment Tool Tab as necessary, and select the Purple Fringing tool.
  2. Zoom to at least 100% in an area displaying a fringe with a purple hue along a high contrast edge. Note the inclusion of complementary cyan, magenta or yellow-green fringes usually indicates chromatic aberration.
  3. To reduce the intensity of the purple fringing, drag the slider to the right. If the fringing is severe it may not be possible to remove it entirely.
  4. The setting can be copied and applied to other image files as a Style or Preset, if required.

Diffraction correction

Overcoming diffraction is challenging for photographers trying to maximize sharpness through the use of extended depth of field, and it is especially burdensome in close up work and landscape photography, where small apertures are crucial. Diffraction first reduces micro-contrast and then resolution, as you stop down beyond a certain aperture, which is known as the diffraction limit. Stopping down beyond that point will only reduce the resolution.

Capture One’s Diffraction Correction option enables you to close down at least one stop further than you would be able to do so without it. Selecting this option helps mitigate the effect using a sophisticated deconvolution algorithm to sharpen the image and restore some of the fine detail that was lost during capture. Note this feature is not enabled automatically as it is processor intensive when images are viewed at 100% magnification and, when the time comes to output files, it extends processing times. Enabling this tool and the application of Sharpness Falloff correction can be considered the first stage in capture sharpening. Note this feature is compatible with RAW files only.

  1. Select an image or multiple images from the browser.
  2. Go to the Lens inspector and select the Lens Correction panel.
  3. From the Lens tab, enable Diffraction Correction with a check mark to apply the correction.
  4. The setting can be saved as a component of a Lens Correction User Preset and applied to multiple images.

Diffraction correction with a manual lens

When enabling the diffraction correction option in the Lens Correction panel, Capture One doesn't rely on the lens profile it reads the EXIF metadata in the image file to optimize and apply the deconvolution algorithm instead. If some of that data is missing, such as when using adapted lenses and manual, mechanical lenses without a data interface, you can add it manually in the Movement tab and still benefit from the diffraction correction feature. Accurate record keeping is required for the focal length and aperture used at the time of capture.

  1. Select an image or multiple images (if they were captured with the same focal length and aperture) from the browser.
  2. Go to the Lens inspector and select the Lens Correction panel.
  3. Click on the Movement tab, and manually enter the focal length and the taking aperture.
  4. Click on the Lens tab and enable the Diffraction Correction with a check mark to apply the compensation.
  5. The setting can be saved as a component of a Lens Correction User Preset and applied to multiple images.

Distortion correction

Capture One’s Distortion slider can be used to fine-tune either barrel or pincushion distortion correction, depending on the lens profile selected. The slider functionality automatically changes to suit the type of distortion. This is particularly convenient when the profile contains data for both barrel and pincushion distortion such as that found with zoom lenses.

When there is no suitable lens correction profile available, the user must select the Generic profile when barrel distortion is present, or choose the Generic Pincushion profile to remove pincushion distortion. Note, complex or waveform distortion can only be corrected by a lens profile.

  1. Navigate to the Lens Correction tool, and check the profile for your lens has been be selected automatically, otherwise search for a suitable profile from the drop-down menu.
  2. Adjust the Distortion slider for that profile to 100% to fully correct this issue (if there is one).       
  3. Alternatively, when there is no suitable profile available, select from either the Generic (i.e., barrel) or Generic pincushion distortion profile, depending on the distortion visible in the selected image.
  4. Adjust the Distortion slider while observing the effect on the image against the displayed grid in the main viewer. 
  5. Switching between the two Generic profiles during adjustment will reset the slider to zero.
  6. The setting can be saved as component of a Lens Correction User Preset and applied to multiple images.

Correcting soft corners

Softness or a loss of sharpness can occur in the corners and outer zones for many reasons and is quite common in wide-angle and ultra wide-angle lenses. Soft corners are often seen as a desired retro-focus effect. However, with the Sharpness Falloff slider, Capture One can help correct this effect if it is unwanted.

  1. Select an image that you want to correct.
  2. In the Lens Correction panel, check the profile for your lens has been be selected automatically, otherwise from the drop-down menu, search for a similar model or use the generic profile options instead.
  3. Adjust the Sharpness Falloff slider for that profile to 100% to fully correct this issue (if there is one).
  4. Alternatively, experiment with the image at 100% to get an appropriate setting. Higher values than 100% are possible and increase the effect of the correction.
  5. The setting can be saved as a component of a Lens Correction User Preset and applied to multiple images.

Reduce light falloff

Light falloff arises because an image is exposed more at the center of the frame than at the corners. The distance light has to travel from the lens to the sensor is greater at the edges than it is at the center and, therefore, less light reaches the sensor from the lens at those more oblique angles. In addition, some of the outer off-axis light is restricted by the lens barrel, which is known as vignetting. This effect is most common with wide-angle lenses that are used at the initial aperture (i.e., wide-open). Falloff due to vignetting can usually be reduced by stopping down.

  1. If you have a profile for your lens, set the amount to 100% to result in a completely flat and even-looking image.
  2. Alternatively, use a generic profile and manually set the desired amount with care. Higher values than 100% are possible and increase the effect of the correction.
  3. The setting can be saved as component of a User Preset and applied to multiple images.

Recording and entering shift movements

When capturing images with shift movements, the shift value can be manually added to text fields in the Lens Correction tool's Movement tab. In addition to being used by that tool to optimize various corrections, the LCC tool can also adopt that data to optimize the LCC profile for illumination fall-off.

Vertical shift 

Vertical movements, sometimes referred to as rise and fall must be entered in the Y field. Rise should be recorded as positive (+), and fall as a negative (-) value, with the minus (-) sign being be used to indicate movement in the opposite direction; in this case indicating fall. The field will not recognize the + sign, thus it’s unnecessary.

Note, for the purpose of adding data in the Movement tab, a parallel downwards shift of the IQ digital back is the same as a parallel upwards shift of the lens and, therefore, should be recorded as a positive value.

Horizontal shift

Horizontal movements, left or right, should be entered in the X field. When operating the camera from behind (i.e., when looking at the subject), movements to the left should be recorded as positive (+), though as with vertical shifts, there’s no need to add the + sign. Movements to the right should be recorded as negative, and the (-) minus sign used. 

Compensating for camera orientation 

The shift X/Y entry fields in the Movement tab take image rotation into account. However, you may need to take note during capture if you’ve mounted the camera in a vertical position, especially when making horizontal movements, left or right. If a vertical image isn't automatically re-oriented in the Browser from the file's metadata, for example, then shift values for horizontal left/right movements must be entered in the Y field instead.

  1. Go to the Lens Correction tool and click on the Movement tab in the tool.
  2. If the focal length and the taking aperture can be detected, the values will automatically be shown in the corresponding fields. Otherwise manually enter the information.
  3. Enter the shift data for the X and Y axis. Changing the shift parameters will have a positive benefit on the distortion and light falloff corrections in particular.