How internet security works (explained with tennis balls)

Security on the Internet is full of buzzword terminology and endless acronyms: Public keys, private keys, key exchange, SSL, SSH, PGP. In an attempt to clear up at least a little bit of the mess, we have put together a video that explains basic Diffie-Hellman key exchange using tennis balls. View this and other videos at
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It works!

It works!
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I don’t found on the Pentax K100D manual the procedure to use the old manual lenses.
A kind user of the newsgroup gave me some useful directions.
Here it is my answer.
The lens used is a SMC Pentax 50 mm 1.7 (#4048966) at f/4.

Non ho trovato sul manuale della Pentax K100D la procedura per usare le vecchie lenti manuali.
Un gentile utente del newsgroup mi ha fornito alcune utili indicazioni.
Ecco la mia risposta.
L’ottica usata è un SMC Pentax 50 mm 1.7 (#4048966) a f/4.