Enlarge the rang of aperture - by: max

Hi,

I try to use a small len 100mm/f3.5 to guide my cannon 200mm/f2.8 Len , this would be a very small setup. But ekso keep saying it only accept aperture value start from 50, but my is 100/3.5=28.57, can you enlarge the rang of acceptable aperture value ?

Thank you .
Max