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Forum: Pentax DSLR Discussion 08-15-2010, 07:55 AM  
K7 maximum allowed hotshoe trigger voltage
Posted By mppuser
Replies: 16
Views: 12,218
Thanks.
I missed this one.
D.G.
Forum: Pentax DSLR Discussion 08-15-2010, 07:45 AM  
Wireless flash trigger option for K7 help
Posted By mppuser
Replies: 28
Views: 11,128
Sorry....this is not so.
Do some tests on Miranda guns and you will see.
500CD = 2.85v + Positive centre contact
630CD = 8.2v - Negative centre contact
700CD = way over 100v !
All are multi dedicated units, the 500CD being manufactured during the 1980's
Also centre contact polarity is important. It must be + Positive!
The rule is ALWAYS test before attempting to use on a camera and never take anything for granted. Production changes mean voltages can be different from one gun to another although of same model number.
Forum: Pentax DSLR Discussion 08-15-2010, 07:32 AM  
Wireless flash trigger option for K7 help
Posted By mppuser
Replies: 28
Views: 11,128
Optical units only work if the area being photographed is dark enough for the slave to 'see' the source flash. Working in an area where 'fill in' flash is required eliminates use of such units due to insufficient light level differences during the flash. This means the slave flash(es) do not fire.
Try shooting in the centre of a large open ended farm barn, trying to match interior light levels with that at each end of the building and you'll see what I mean.
In these situations it must be wireless by radio signal.Optical untis will not work.
Regards
Forum: Pentax DSLR Discussion 08-14-2010, 08:24 AM  
K7 - Max external flash hotshoe trigger voltage
Posted By mppuser
Replies: 1
Views: 3,829
I'm sure we have been here before but without success. So,

1, Does anyone know the REAL max allowable voltage at the camera hotshoe from an external flash gun?

2, Does anyone know the max allowable voltage at the coax connector. (Pentax says it can trigger studio flash units) But, this is general term and we need specifics.

It is most unsatisfactory for a manufacturer to with hold proper and full technical and specification information from owners and not offer an acceptable reason for doing so. It just leaves a bad taste and lowers the standing of the manufacturer with potential buyers.

There are those of us out here who do understand tech stuff and consider this line of approach by Pentax to be unacceptable.
Well,

Has anyone got real and definitive figures here?
Forum: Pentax DSLR Discussion 08-14-2010, 07:59 AM  
Wireless flash trigger option for K7 help
Posted By mppuser
Replies: 28
Views: 11,128
A quick check at Ebay shows a firm in South Wales (welsh Wales, UK) that supplies the above. Camera hotshoe voltage is 3.29v, the max range is about 99feet and the max flash gun trigger voltage is !2v. Wireless channel selection is by 2 DIP switches to select any one of 4 channels.
Supplied with coax leads,they can be used with cameras and guns via a lead or the conventional hotshoe.
I have 2, so can trigger up to 4 guns from one of the transmitters.
Value for money? - Yes. Very!
Operation - Excellent
Problems - None
Minuses - Flash trigger unit could have a more robust mounting bracket._easily solved with some simple home engineering.
Forum: Pentax DSLR Discussion 04-23-2010, 01:38 AM  
K7 maximum allowed hotshoe trigger voltage
Posted By mppuser
Replies: 16
Views: 12,218
Thanks...I am a retired ex photo industry senior electronics engineer.
DG
Forum: Pentax DSLR Discussion 04-22-2010, 05:12 AM  
K7 maximum allowed hotshoe trigger voltage
Posted By mppuser
Replies: 16
Views: 12,218
Ok so there seems to be some difference of views on this but there are two questions....

1 - Max voltage allowed at the Hotshoe

2 - Max voltage allowed at the PC contact

Some idea on 2 would be to note here examples of the trigger voltage of studio flash units
And, the voltage of some which have been used successfully and without damage.

[I regularly use Miranda 500CD guns on the hotshoe connection.They present 2.7v at the gun's hotshoe contacts with NIMh cells fitted.
Other Miranda guns present other voltages i.e. the 700CD is 8.2v
Also, I have successfully modified a Jessop 230ABZ using opto isolator technology but this is not a suitable solution for all high voltage guns.]

Thanks DG
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