The Olympus 7-14 Pro has a 114 degree field of view at 7mm making it super wide and the full frame equivalent of 14mm. At such a wide FOV the optimum size of filters is approx. 125mm which are not manufactured. To avoid having to use bulky and expensive 150mm filters the adapter is designed to maximize the wider range and more popular 100mm filters.
Mechanical vignetting from the holder intruding into the image area has been reduced to the minimum possible for the size of filter and the lens FOV.
Although three slots can be used with no angling of the v6 holder without vignetting, altering the holder to two rails gives more flexibility to angle the holder and still allows the use of two filters which is usually enough.
The field of view at 7mm changes slightly depending on the focus distance. At a close focus distance the FOV is slightly wider than on infinity, which has an impact on vignetting. Sample images shown were taken with a close focus distance of approx. 2 meters, with the camera set at the max 4:3 ratio.
Vignetting at approx. 2-meter focus distance, impact on image corners.
2 slots used vertically – no vignetting
2 slots angled to 12.5 degrees – slight vignetting removed at approx. 7.5mm
2 slots angled to 45 degrees – slight vignetting removed at approx. 8mm
Minor Vignetting is easily removed by slight cropping.