Congratulations Jos. A fine job... On Wed, Nov 15, 2017 at 8:18 AM, Jos de Fotograaf <[email protected]> wrote:
> > Introduction: > My Metz 58AF-1 got defective zooming mechanism than I bought a Metz 58AF-2 > after 3 years the flash tube blew into peaces, I opened it to try to > replace the tube and found out that the tube is too small and can be > overloaded too easy. I reworked the head to fit a bigger tube, but the > flash did not trigger anymore...... > I mostly used the Metz in the automatic mode using the light sensor of > the flashgun, if you know what you are doing, this is very reliable and > accurate and no problems with the bride closing her eyes on the pre-flash! > I decided to use one of my old Philips flashguns, the Philips P36-TLS. > This flash was build by Nissin more than 40 years ago. > > * Very reliable, plenty of them on the secondhand market (in Europe) > * The flash-head is fully swivel-able and tilt-able. > * It has a sub-flash > * It has a manual mode with three levels and > * an automatic mode with three aperture-ISO combinations. > > In automatic mode, it uses its own sensor and the accuracy was more than > good for slide film, so certainly good enough for the K1 sensor. > Unfortunately the hotshoe only has one contact: the trigger contact. > I found out that I could modify the flash and can add a "flash ready" > contact. > The "ready" contact for Pentax is the contact, looking from the back of > the camera, that is the nearest at the right side. > I measured another flashgun with "ready" contact: the "ready" voltage > generated by that flash is about 2.7V. > After firing, the voltage drops to zero and comes back when the gun is > ready for the next flash. > The K1 (and probably all DSLR) uses the signal to > > * to light the flash ready sign in the viewfinder > * to limit the shutter-time to the max flash sync time > * to add "flash did fire" in the metadata of the picture (this is the > most important to me) > > Measuring the trigger contact of the flash showed 3.9V. To ignite the > flash, the K1 pulls it down to zero and after the flash, the voltage goes > back to 3.9V when the gun is ready for the next flash. > > I concluded that probably the ready signal could be derived from the > trigger voltage by connecting them through a resistor. > > After some experimenting I settled for a resistor of 22k Ohm. > > This works perfectly! > > With the 22k connection, the trigger voltage drops to 3.4V and the ready > voltage is 2.3V > > I did some tests to see how critical the value is: > 33k still okay, > 68k --> ready signal too low > 10k --> still okay but triggervoltage drops to 3.2V (but triggering still > fine) > 22k is a good compromise for this flash-camera combination. > > Now I took the DREMEL and cut off the hotshoe that only had the trigger > contact and glued an old hotshoe with trigger and ready contact and the 22k > resistor. > > Greetz, Jos van der Hijden. > > > > > > > > > > > > > > > > > > > > > > > -- > Greetz, Jos > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and > follow the directions. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
