Bulb Flash with a Pentax K5

Hi, I have lots and lots of various Flash bulbs . I also have an assortments of flash guns, Leica Rolley etc.
I like using flash bulbs, because they are not as brillinat white like electronic flashes. They create a slightly warmer picture.
Does anyone know, If I can use them on my K5 Camera without damage to the synchro socket? Some of the guns use a 15 or 22V battery with a 100uF capacitor.
Does the K5 have mecanical contacts or elecronic contacts and are they , if electronic, polarity sensitive?
Can anyone help me with this?
Horst

Flash bulbs are quite different to electronic flash - they burn for longer and need different synchronisation.

I would save the flash bulbs for older cameras that have M synchronisation. FP flash bulbs can be used with some Pentax cameras that have FP sockets, such as the MX, at shutter speeds up to 1/1000sec. These are very long burning so keep going all through the shutter travel.

All dSLR trigger outputs are electronic (thyristor based I believe), and as such are polarity sensitive.

You can always warm up the light from an existing flash with a Stofen colour unit - http://www.stofen.com/store/coloromni.asp

Or, you could experiment with home-brew diffusers and adjusting the manual WB controls of the K5

Matt

Or you could use some gels to warm skin tones and create some nice colour lighting transitions.

Thanks for the Info.
I thought that the trigger is electronic, but wasn't sure. I will check if the centre contact needs to be positive or negative.

I should be able to connect a 3 volt battery in series with a resistor and an Led and see if it flashes for a moment.

Most of the bulbs I have, are non FP. They use the X-Synchronisation, but with a fastest speed of 1/50 sec.

I have some FP bulbs and realise you have to use the M Syncronisation, which is not available anymore.

Thanks again, Horst

Thanks for that Matt. Save me a lot of testing.

Kind Regards, Horst

Horst,
You'll find the comments on this thread may help too.

Because of the electronic interface on the dSLRs it is possible for the thyristor to 'latch' on such that you'll get one trigger but not any more (until you unpower the circuit). Wikipedia's entry under "Switching characteristics" is useful.

You may require a high-impedance buffer to interface to the hotshoe to prevent the electronics latching.

I wouldn't recommend trying to directly drive anything more than a couple of milli-amps

Matt

Hi Matt, the comments on this forum are very helpfull. It gave me something to think about.

I agree, that the thyristors, when connected to a DC voltage stay switched on, as long as the current through it is larger then the holding current.
With a Bulb flash, this in itself should not be a problem, because the bulb open circuits after it has fired. No current can flow until a new bulb is inserted. The SCR has then long switched off again.


The problem I believe is more the initial high discharge current when firing.
It makes a lot of sense, as pointed out by you, to use some sort of interface which requires a low triggering current. Especialy since I dont know the chararistics of the SCR used. So it is better to be save than sorry.

Thanks, Horst