It does depend on the CM and its printing and placement equipment. We currently use DEK printers
with both high and lower resolution cameras. The high resolution types have a relatively limited
field of view, so beyond 40 mils sometimes becomes an automatic search chore.

Typically, we use either 40 or 60 mil fids with appropriate dark backgrounds to ensure accruate
recognition using high resolution grey scale imaging. Corresponding fids, as apertures or circles,
are used on stencils with appropriate light backgrounds.

Some placement equipment is a big more selective. Our Fujis mostly enjoy eating what the DEK's
prefer.

Earl Moon