off camera hot shoe question

[Keith Baran]

Hi, I just started exploring using my hot shoe flash remotely. I apologize if this question has an obvious solution, but I have experimented for weeks and Google many sights searching for an answer...
I use a Pentax k10. and 2 vivitarDF383 flash units. If I use either of the flash units on camera the power from these units is extraordinary. Now the dilemma, just to experiment with off camera flash I set the Vivitars to manual, zoomed all the way out to 85, 1/1 power, located 1 foot from the subject,my K10 is in manual F2.8 60th of a sec shutter. First pic is with no flash, it is very dark with ambient light, second pic is just the k10 flash, it turns out very bright almost over exposed, third pic is k10 flash and one Vivitar, it turns out only a tad brighter than the first pic with no flash, fourth pic k10 flash and both Vivitars located 1 foot on either side of the subject pic is just a tad brighter than the first with no flash. At this power, f stop, and three flash unit shouldn't the pic be completely blown out and over exposed? All three flashes are firing and distances between all components remain unchanged.
Will someone please enlighten me or at least point me toward some reading that will answer this question
Thanx in advance for any help
Keith Baran

 

[kundalini]

At f/2.8, full power, zoomed to 85mm and 1 foot away, it should be baking your subject. If these are subsequent shots, is there a chance you have any kind of bracketing set?

Pictures with corresponding settings might help.

 

[KmH]

+1. You nuked 'em.

 

[GeneralBenson]

So what you're saying, is that when you are using them off camera, they aren't very powerful?

Hw are you triggering them? Is it just a slave cell that triggers from your pop up flash? If so, that your problem. The K10 flash (like most pop-up flashes) has preflashes that help it find the correct flash exposure. So what ends up happening is that the pre-flash sets off your flashes before the exposure is made, and then they aren't recycled in time for the real flash. With most flashes, they just wouldn't even go off if they aren't fully recycled, but since your exposures with the flashes are slightly brighter, i wonder if they still allow themselves to go off before they are fully recycled, in which case, they would just be severely underpowered.

That's my best guess.

 

[Keith Baran]

Thanx GeneralBenson, that is exactly what is happening, I ordered a radio set this morning. Thanx for your response, appreciate it