LEE Filters system, polarizer and vignetting on EF 17-40.
Also check out www.leeduguid.com.au/blog/tips/filters-filter-holders-and... about this issue.
I have the LEE Filters system with EF 17-40 on a full frame EOS 5D II with the Wide Angle adaptor ring. With 3 2mm slots for the LEE resin filters, the Lee holder starts barely vignetting when the holder is turned about 40 degrees. Removing the Front cover plate will remove the vignetting with this setup of 3 slots. The Front cover plate only causing vignetting. Cutting away some into the middle of the Filter holder guides will also help a little with vignetting. Sanding down the guides may also help, moving the filters closer to the lens and the filters closer together. Imo LEE should have made the holder-system with better focus on vignetting so that one could use the full width of the 100mm filters. The distance across the holder between the Filter holder guides is only 92 mm. The guides should have been placed closer to the corner of the holder, with no part of the guides closer to the centre of the lens than 50 mm (2x50 is 100). The big problem with vignetting starts when you want to use a polarizer with the filter holder.
I am about to redesign the adaptor ring. The ring will be fastened to the lens where the lens hood is screwed on. An 86mm Heliopan slim polarizer will be screwed into the front of the adaptor. The filter glass will be about 0.7 mm from the front of the lens. The front of the filter will be protruding about 5.4 mm from the front of the lens. The reason I chose Heliopan 86mm is because it supposedly is the slimmest 86mm polarizer made. I hope I am right. This setup with some slimming and cutting of the guides should make it possible to use 2 LEE resin filters in addition to the polarizer without vignetting. I also have some Hitech filters made by Formatt UK that supposedly is a tad thinner than the LEE filters in case two LEE filters still causes vignetting.
I’ll keep you updated of the progress. Let me know if you would be interested in such an adaptor if it works the way I want it to. This would be an adaptor made specifically for the EF 17-40. Could anyone maybe help me with finding the exact, 0.01 mm margin, dimensions of the front of the EF 17-40, or any other lens for that matter? This to get as snug a fit as possible.