The lens is smaller than the predecessor, the FT Zuiko 7-14mm f4 but a bit larger than the Panasonic µFT 7–14mm f4. I tried hard to build a filter holder for 100 mm filters and succeeded!
I built a protoype of the filter holder. Now, I’m happy with the prototype, so the holder is already in production. The current design has reached production quality and several batches have been shipped.
I couldn’t resist building a prototype for 100 mm filters. It works, although with a few restrictions. Placing the holder exactly on the lens takes some training. Slightly wrong placement leads to vignetting. Since the lens is software-corrected, the RAW image covers a wider field than the resulting JPEG. There is no vignetting in the JPEG but there will be visible vignetting in the uncorrected RAW, depending on focus distance.
The advantage of using 100mm filters rather than 130 mm filters is worth accepting vignetting in uncorrected images. Filter availability and pricing of 100 mm filter systems versus 130 mm filters are more than convincing.
Filters are held by friction. To provide suffficient friction, one or two o-rings are used, depending on thickness and production tolerances of the filters. I use o-rings of 48×1.5 mm dimension. You may also use rubber bands of normal household quality. They will wear off faster than o-rings though.
There’s good news for those, wanting to use more than one filter. Although the design is extremely tight, I managed to add an additional rail for a second filter! Actually, it’s half a rail, stabilizing the filter along the sides, when attached to the first filter by two rubber bands. A thin gap between the filters will prevent scratching.
To mount the filter holder tight on the lens without scratching it, two thin self adhesive felt pads are used. They should have a size of 50×10 mm.
Since the mold for dye-casting reached the end of its lifetime, I now offer the filter holder as SLS 3D-print at my Shapeways webshop. Please place orders directly there.