Photographer John Robinson uses the Universal Lens Calibrator

Phase one digital back users have been taking advantage of Capture One's unique LCC (lens cast calibration) feature for a number of years. What's it all about then? Digital back sensors have always had incredible resolution making them capable of resolving the coating on lenses which leaves a non uniform colour cast on the resulting images. Digital SLR cameras have caught up, offering a high enough resolution to produce the same side effects, although subtle it is difficult to remove and to add further salt into the wounds your digital sensor will also pick up the colour cast of your filters, sensor dust and vignetting while technical lenses with tilt and shift movements, when utilized cause light fall off, a darkening at the edges of the frame. All of the above are unwanted side effects which are difficult and time consuming to remove. That's were the combination of Capture One Pro and the Universal Lens Calibrator comes in.

The kit comes in a protective cover and consists of an instruction manual and two calibration cards, 1 large 150x150x3mm card for wide angle lenses and another 100x100x3mm card for standard lenses. The latter fits directly into your filter holder giving you more freedom.

The kit is very simple to use. My approach to the images I make was no different other than the fact I had to remind myself to hold one of the white cards in front of the lens after I had set up my composition and camera settings, i.e., shutter speed, aperture and any tilt, shift movements of the lens. As a side note the manual states that your exposure for the lens cast calibration shot should be two stops over your base exposure, to do this you would simply adjust the shutter speed by two stops, leaving the aperture settings unchanged. After taking an image of the card readjust the shutter speed back to your original settings. Now you would proceed to capture your image as normal as you have the file required to correct unwanted side effects when you have the images in Capture One Pro.

After downloading my images and choosing which image to work on, I would then select the LCC (lens cast calibration) image of the white card which I had taken while in the field. From there I would select the lens tab in Capture One Pro and open the drop down menu for the LCC tab where you are provided with a few options. I chose analyse technical wide angle due to using lens movements (a combination of tilt and shift on technical lenses).

This results in Capture One Pro analysing the image, removing any colour cast which had been introduced by the lens/filter combination in use. Capture One Pro also provides two more options which will remove unwanted light fall off and dust removal. The former is something I didn't use as this will remove the effect of any neutral density graduated filters I had used in the field, while the latter was used and removed sensor dust from the image.

John Robinson

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