Well I'm not sure what a radial guider is, but i use single filters when i do prime focus photography using my DSLR.
With both the 300mm Lens, and the Tak 106 the filter fits in behind the rear element of either.
The 300mm has a drop in slot, and the Tak screws in behind the element, and every thing else needed for imaging fits over it. (the filter).
This may be of some help to you.
Leon
