Problem Statement:
Mounting filters on LF wide angle lenses has always been problematic. Screw-on filters will tend to vignette or be extremely expensive in larger sizes. 100mm x 100mm/150mm square/rectangular filters provide a more universal and cost effec tive solution across a set of lenses, however they can also present unique probl ems when used with WA lenses. The use of a center filter which is often require d with WA lenses only compounds the problem. For example, Lee makes a fairly ex pensive adapter (FK100) designed specifically for the Schneider 72 & 90 SA XL le nses when used without a center filter. Indeed, this holder does the job. Howe ver, when a CF is used on these lenses, there isn't a non-vignetting solution av ailable when using 100mm filters. In fact, the filter element is larger than th e filter. To me, investing in a separate set of even larger filters (e.g. Cokin X-Pro) is something to be avoided if at all possible. The other part of the eq uation is the mounting of an effective compendium on WA lenses, both with and wi thout filters. Here again Lee Filters brought to market a wide angle lens hood with a self support bellows. Because Lee pretty much adapted components from ot her products in making this compendium, the end result is not really tuned for L F use where lenses get very wide and/or significant movements are possible. My experience has shown that if no filters are used, the hood can be somewhat helpf ul. If filters are required, it is almost impossible to keep from vignetting af ter fitting the hood. For my purposes, the hood with built-in slot(s) wasn't us eful because I'm often using grad filters or polarizers where independent rotati on of the filters relative to the hood orientation is required. If a CF is used , there is no solution.
These issues have made me brainstorm alternate filter holder/compendium design c oncepts geared towards the problems LF shooters face. I've made some crude prot otypes of a filter holder design and shot some film to verify their ability to n ot vignette. At this point, I have confidence that the holder design will work with two 100mm square/rectangular filters fitted over a 47XL, 58XL and 72XL thro ugh their complete movement range with a CF. Although I don't own one, it shoul d also work with the 90XL. I'd guess that three or more filters would be possib le with the 72XL and 90XL and maybe even the 58XL (although this is probably rig ht on the edge). I also have preliminary concepts for a design which would allo w independent rotation of multiple filters and a lens hood which would work with this range of lenses, CF's and 100mm filters.
Certainly more design/prototyping is necessary before it's ready for even a prof essionally built model made out of the actual materials I had in mind. I will n o doubt see some version of this concept through to a model for my personal use. However, I'm curious in understanding if a wide enough market exists for a bet ter holder/compendium to justify addressing this as a small business opportunity . This second step is a very large step because of the implications it brings ( more professional mechanical design, tooling, design for easy manufacturing, US and select international patent(s), cost, price, sales channels, distribution, . ..). Another approach I've though of is to setup a low volume custom manufactur er with this design who could then build them on a per order basis.
I'd be interested in a discussion of what I've presented here towards the goal o f critiquing the product requirements, and understanding if there is enough of a market to proceed with this idea in a commercial way. What price would someone would be willing to pay for such an item?
Some of the open product requirement issues in my mind are:
* Importance of independent rotation of multiple filters (e.g. using multiple gr ads or a grad and a polarizer).
* Importance of integrating a compendium into the design.
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