Skill Discussions

Rangefinding is the strength skill. When scanning, a higher strength gives a better resolution, meaning that your probes don't have to be as close to the signal to get a high quality result. At higher skills, it's relatively easy to hone in on a signal while skipping bands. To be honest, once you pass the threshold of "scannable" -- which is about strength 80 for signatures -- then main benefit is that you don't have to narrow your range as far. For instance, I can easily pin low sec 6/10s without ever hitting .25 AU with a strength of 120 something.

Deviation is a bit harder. To my knowledge, the exact deviation formula has never been worked out. What we do know is that deviation is a random variable that makes a signal appear further from its actual location. Reducing deviation means that your signals appear closer to where they actually are -- which, again, allows you to hone in on them more efficiently.

Whether taking either to 5 is worthwhile is, of course, up to you. Rangefinding is nice at 5 because it allows you to fit T2 rangefinding arrays to boost signal strength on unbonused ships (like, say, an exploration Ishtar) and still be able to hit tough signals (like, say, 10/10s). With pinpointing at 5.... Well, I don't know. I have it and occasionally the deviation monster still rears its ugly head and I miss a signal. But only very occasionally. It certainly helps but I wouldn't say it's critical unless you're doing combat scanning.

I wrote a post about this here.