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08-05-2018, 12:15 PM   #1
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Flash REGULA Variant 740-2MFD for Pentax K5

I start this thread, because I bought a cheap REGULA Variant 740-2MFD flash. He has a five positions switch on back, one of them marked "Pentax". I did not find details or an user manual for this flash, but I want to use it with my Pentax K5.
I understand that Pentax genuine flashes have a triggering voltages up to 8Vcc. I read somewhere in Internet that Pentax digital cameras accepts up to 24V (am I wrong?), that means one camera support and could control, directly, three flashes connected (am I right?)
The REGULA Variant 740-2MFD flash light has a triggering voltage between 13.7-14.2 Vcc on "Pentax" position switch (in fact, these voltages are on all five switch positions) and, in theory, it could be supported by Pentax K5.
Question: it is safe to use this flash with my camera, without destroying it?
Thank you for the answers and advices.


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08-05-2018, 05:03 PM   #2

Join Date: Mar 2010
Location: Frankfurt am Main
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I own the Regula Variant 742-2 SCA since film days (it is my strongest flash).
It looks very different from the 740-2, but the inerts are the same except:
1) It is not switchable for brand support, instead it uses the SCA300 system.
2) The small flash is detachable and can act as a seperate slave flash.

I used this flash several times with my K200D without problems.

By the way, there is (was?) an ISO standard for camera flashes, saying every camera should tolerate voltages from external flash units up to 24V without problems. Sadly, even some manufacturers who took part at the setting of the standard, did not comply with all their models.

There must be many old threads related to the subject, and members tried to get precise information about what Pentax DSLRs do really tolerate.
Asking 5 different Pentax representatives, you got 5 different answers. The reason for this is probably shown by the answer of an European service center:
The cameras are designed to tolerate (theoretically) up to 36V, but as all original Pentax flashes use low voltage, NO ONE in Japan ever tested what the real limit is.

And even if they knew it: I doubt they would add this information to the specifications. They want to sell Pentax flashes.
08-05-2018, 06:20 PM   #3
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Also I wonder if that Pentax position is for film Pentax TTL operations. In which case it will not work in that mode with any of the modern Pentax digital cameras since they don't provide that mode. It will work in Auto or manual modes that don't rely on TTL info from the camera.

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