Originally posted by maxfield_photo A non Pentax cable won't have the contacts in the right place on the hotshoe, so you'd need to buy two cables, a Pentax cable for it's contacts, and a non Pentax cable for it's longer cord. I considered it because it's a more elegant looking solution, but in the end I decided that, a) it was too expensive (the 25 foot cables aren't cheap), and b) my soldering skills leave a lot to be desired.
By non-Pentax I meant not
made by Pentax. It of course has to be made
for Pentax, like the one on eBay I linked to - it has all the contacts in all the right places for P-TTL and is much cheaper than the genuine item so no worries about damaging it during the modification.
The soldering is not difficult at all - even the most basic soldering skill is more than sufficient as the contacts are very easily accessible. Even if you've never soldered you can learn the skill required for this operation just by watching a couple of youtube videos on the subject.
The cable can be any old network cable but for reliable operation with long cables it may be better to get a 5 core plus shield cable which does not have the wires twisted together in pairs.