Using independent flash ( e.g. Vivitar 283 ) with K5?

It's possible because not all 283s are the same. I have measured two identical looking samples, one of which had a trigger voltage of under 20V but the other was around 290V. Obviously over the years the design has evolved.

I wouldn't risk it and would stick to modern flashguns, even though it may be OK if it's not you'll potentially fry the camera's electronics.

Check the place of manufacture (on bottom of unit). If it says made in Japan it is the older version and will be of the just shy of 300V variety. Made in Korea is latest and will be safe in general. But considering the value of the camera in question, a test with a digital voltmeter is mandatory really even if you have to buy one - a basic voltmeter will suffice - you don't need extreme accuracy to diff < 10 or 20v versus > 250V. Just charge flash off camera and discharge by connecting the meter across the contacts (with flash pointing a way from you

[ BTW 285HV's are also likely to be OK, but older 285's (without HV appended) can be any voltage. I have a very early 285 and it is low voltage, but later ones are not. Strange. So actual testing is the only way to tell. ]

Or - if yours tests out too high - pick up another later 283 and a cheap optical trigger and you have a 2-flash setup while avoiding having to learn a new flash model's operating procedure. That was the path I took.

I do believe the older vivitars that are capable of frying your d-slr are the same ones that would have fried your mz5n... you should be ok to use it.

I did some investigation work on the interface between the Pentax K10D, K20D and the Vivitar 283 when I needed to build an system to fire a number of them simultaneously. I have owned more than twenty of these units, but after selling a few I am currently down to my last seventeen! Here is a brain dump of what I found.

The K10D and K20D have a thyristor device as the switching component. High voltage is not a problem for this circuit and I have regularly used Vivitar flashguns with 270 volts on the hotshoe on my cameras with no ill effect. I would imagine that the K5 is the same.

As other posters have outlined, the voltage on the Vivitar 283 hotshoe varies with when the unit was made.

Original Japan units are 270 volts.

Japan made units with a red paper disc sticker on the inside of the battery door are low voltage (around 10 volts or so).

Korea made units are low voltage.

China made units are low voltage.

Circuits to modify the flashguns to low voltage trigger are available online and for various non Pentax reasons I have so modified a number of mine. Avoid those with an opto-coupler as these latch up the Pentax switching thyristor. Google for Jean Paul Brodier whose triac circuit I find to work well.

Most websites show horrible construction, it is quite possible to build an interface into the flash head without any detrimental effect on the appearance or function of the unit. The yellow wire is the trigger, the blue the common.