Chromatic Aberration?

March 24, 2011 by 4 Comments

 

Zoom lenses covering large zoom ranges often compromise image quality in various ways – but almost all show some degree of chromatic aberration.  Especially zoom lenses going ultra wide have a tendency to show lots of chromatic aberration in the wide end of the zoom range.

The Lens Tool in Capture One Pro 6 can automatically fix chromatic aberration in any RAW file by analyzing the content of the image.  This ensures the best possible correction customized for your images compared to corrections based on a few lenses in a lab.

With tool presets for the Lens Tool, you can create presets for your own lenses.  Lens Tool presets work very well even if your capture conditions are not 100% identical.

The two pictures above show a 200 % zoom of the left side of a picture which has been shot with a prosumer zoom lens at its widest zoom range. The left image shows a severe amount of chromatic aberration with lots of magenta and green colors along all vertical structures in the image. This level of chromatic aberration is quite disturbing and should be fixed. To the right, you see the same area after it has been fixed in the Lens Tool in Capture One Pro 6. All the false colors have been removed and the image looks natural.

 

Create your own presets to deal with chromatic aberration

To fix a problem with chromatic aberration, open the Lens Correction Tool found in the Lens Tool tab.  Under the drop down menu for chromatic aberration select analyze.  After a few seconds, a correction based on the result from the analysis will be applied.  If you have zoomed into an area of the image with severe chromatic aberration, you will immediately see the fantastic effect of the tool.

When photographing landscapes with wide primes, I usually shoot at f5.6-f10. With the lenses I use, I find that the amount of chromatic aberration is practically constant in that f-stop range which means that you can make presets that works perfectly.

When using zoom lenses, the amount of chromatic aberration is highly dependent on the zoom rate (focal length) which makes it more difficult to use presets. Nevertheless, I find them quite useful.  For my carry-around zoom lens, I find that I only need to fix chromatic aberration for the widest end. I have made three presets: one for 17mm, one for 20mm and one for 23mm.   

The benefit of using a well-made preset is that you can correct a series of shoots very fast by copying and pasting the correction from the preset to a selection of images.  Remember that the Search and Filters functionality in Capture One Pro 6 can help you find all shots made with a specific lens and focal length.

When selecting an image for making a preset, you should select an image which has been shot at your typical shooting f stop and focus distance. It is also important that your target image contains structures all the way from the center to the edges of the image. If you plan to shoot an image for making a good preset, consider turning your camera to insure good coverage from corner to corner like in the image below.

Often you will see that zoom lenses with large zoom ranges also suffer from barrel distortion and some sharpness fall-off. When making your presets, you can off cause add these types of corrections to your preset.

Filed under Capture One Tips & Tricks Tagged with , , , ,

The Secret HDR Tool

January 13, 2011 by 37 Comments

 

Used in the right way, the LCC Calibration feature in Capture One’s Lens Tool can be used to create beautiful HDR images.

The LCC feature is designed to calibrate and compensate for unwanted Lens Color Cast as well as Light Falloff in the lens. It is the Light Falloff compensation feature we will demonstrate here.

For HDR purposes, the trick is to use the file you want to work with as the reference file for the LCC Calibration.  In this case, the LCC Calibration file generates a gain map of the different lightness variations in the image. Bright parts of the image will not be gained, but dark areas will get a high gain factor.  When the LCC Light Falloff compensation is set to 100%, the system tries to even out the lightness differences in the image.  Of course, this does not make sense, but if you set the Light Falloff compensation to something between 10-35%, you will achieve a very useful effect.

Combine this with some negative Exposure compensation and you can achieve some really amazing HDR images.

 

Create Beautiful HDR Images

The image on the left has come straight out of the camera and shows a too wide dynamic range. The foreground is much too dark, and the sky is almost blown out. The image on the right is the result of applying a LCC Light Falloff compensation of 35% combined with some negative Exposure compensation. Surely a stunning improvement of the image.

 

A step by step instruction:

Step 1:

Create a LCC Calibration file in the Lens Tool.  Use “Exclude Dust” as dust in the image is inappropriate here.

The Color Cast and the Light Falloff check boxes are both automatically checked after the LCC Calibration file has been generated. 

Step2:

Uncheck the Color Cast check box and adjust the Light Falloff slider to somewhere between 10% and 35%.

With Light Falloff at 35%, the image looks much more natural with plenty of details in the originally dark foreground.

Step 3:

In order to recover the highlight details and to restore the original twilight feel of the image, I add some negative Exposure as well as some Saturation.

Two more examples of how the LCC tool can be used as a very efficient HDR tool:

Capture One also has a specially designed High Dynamic Range Tool, which is used to handle images with High Dynamic Range.  Normally, I will try to see if I can achieve what I want using this tool.  However, sometimes I find that I can do even more dramatic corrections by using the LCC feature or by combining both techniques.

Filed under Capture One Tips & Tricks Tagged with , , ,

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