Lens stacking is fun, and works quite nicely for me! A 150mm with reversed 50mm will give 3:1 macro, or an approximately 8mm wide frame on a Pentax ASP-C camera. In my experience, this ratio works pretty well for many of the smaller jumping spider one finds on the brick walls of homes in my area (Montreal, Canada), but is not enough for the
really tiny jumpers. (Here's
a zebra jumping spider shot with a very similar setup - Pentax-M 150mm F/3.5 plus reversed Pentax-A 50mm F/1.7) I also think that some of the more spectacular Australian jumpers - like those of the Maratus genus - are in the 3-5mm range, making them reasonably appropriate for a 3:1 setup, if perhaps a bit on the tiny side... When approached carefully, jumpers tend to be curious and inquisitive, and will often jump on the lens rather than run away, which can be equally infuriating. Now go get'em!