How do I use a flash?

The power of a flash is usually given in the form of a "guide number" - which, theoretically, tells you the distance in metres that a flash will illuminate at (usually) ISO100.

The built in flash on your K10D has a guide number of 11.

The AF160 has a guide number of 16.

The AF200 has a guide number of 20.

You'll notice that the Pentax naming convention usually includes the guide number (followed by a zero) in the name of the flash unit. For example, the AF360 has a guide number of 36, the AF540 has a guide number of 54, etc.

You can get details on all the Pentax flashes on Bojdar's site. Be aware that not all companies use the same naming conventions so it's worth looking up values of third-party manufacturers (Sigma, Metz, Vivitar, et al) seperately.

that's a great web site and seems to tell you all you need. I'll be keeping an eye out for a second hand ttl with bounce/swivel next, but for now better temper my paypal account

really helpful stuff.

By far the best flash to use, unless you MUST have P-TTL, is the AF500FTZ.

It's powerful, has full manual control of output, has a built-in sensor for triggering, and also has strobe flash for those who like to experiment.

They appear on Ebay regularly at silly prices, but with patience you should be able to find one for around £60.00.

I have a number of flashguns, but my two 500s get the most use.

G