Eraser an essential part of my photography kit?

[Wazza999]

Went out today with my new (2nd hand) Pentax K7D and trusty K10D. I wanted to swap the lenses but the K7 wouldn't recognise my Tokina 19-35, yet it continued to work like a charm on the K10? The Pentax 16-45 was happy on either body. After scratching my head and forensically going through the set-up menus to no avail, I hit on cleaning the lens contacts with an eraser, et viola the lens sprang to life. I presume mount tolerances are such that the contacts weren't pushed together quite so well on one body. So I think the eraser will be an essential part of the kit. Fortunately I had a rather hard Staedtler Techniplast eraser which is made of some sort of synthetic compound which doesn't shed bits of rubber to get into the cameras works. So something else to add to the list of things erasers are good for cleaning, along with battery terminals, contacts on memory cards and computer boards.
Wazza

[martycon]

A post without a picture? Wazza, I would like to see demonstration of the erasing action,

[Wazza999]

Hi martycon, not much to demonstrate, just rub the contacts be they the gold contacts on say an sd card or contacts on a lens mount with the rubber as one would when rubbing out pencil on paper. This removes fingerprints without resorting to solvents such as alcohol. Probably also removes light corrosion.
Wazza

[WhoDo]

Yep, that's something that we in the computer game have known for some time as an effective method of cleaning gold contacts on expansion cards and RAM DIMM/SIMMs for computers. It MUST be a pencil eraser though; not one of those hard, gritty compound erasers you may have used at school for erasing biro and other inks. And it must be used very softly or it will take off the thin layer of gold along with the grime.