Upload & Sell: On
The 100 mm filter size is going to be a very close fit, and may not allow much room for any shift. Also, I think a holder is going to be difficult, but possible. All the standard holders have a round hole in them at about 100mm diameter. The 17 TSE would really benifit from a square hole near 100 mm in size, so that the full width of the filter can be used at the corners of the field of view. That would take a special holder, and a larger mounting system, perhaps square rather than round. I am considering adapting Lee filter holder parts to make such a filter holder. And that is one benifit to hand holding if you do it just right, because it is possible to make use of the corners. I just happen to hate hand holding.
The Colkin X Pro with its 5 1/4 inch width would be much easier to work with, but the number of filters available seems limited compared to 100mm width filters. I guess I need more research on the X Pro before going with 100mm. I do know my Colkin P filters will not work at all.
Also, the mounting method needs to have good alignment and position, so tht it can reliably hold the filter very close to the front element, but also prevent any occurance of making contact with it. The lovely glass element that sticks out forward almost 3/4 of an inch is very nice to look at, but I sure don't want to scratch the front surface. I have all ready ordered a spare lens cap for my 17 TSE so that I can try to make use of part of it for a secure mounting. The lens cap bayonet is the best choice to mount to if possible. It is fixed in relation to the front group of the lens as far as rotation. The rubber ring just behind it is the focus ring, and turns as you focus, so I sure want to keep it clear for easy use if possible.