What pens do you use for marking focus wheels? I always used a mechanical pencil on Prestons, but I've been finding it's not visible enough on the hi 5 (I think because of the backlit ring vs Prestons front-lit ring).

I've heard good things about Staedler Lumocolors, does anyone use those? What size?

I like that pencil can be easily erased but won't smudge easily, and won't stain the ring if left on for too long...so ideally looking for a marker with the same properties.