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aeromole

Member Since 10 Aug 2009
Offline Last Active Oct 06 2013 11:42 AM
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Posts I've Made

In Topic: Little micro strobe batch!

25 June 2013 - 09:27 AM

The D90 will only sync up to 1/200 with a non-Nikon flash, though it will sync at faster speeds with a proper Nik flash.  Can't afford one of them....in an underwater housing as well!

 

At 1/400th, the shutter is covering perhaps 10% at the bottom of the image.  1/320th, it will be less but still visible at 1/250th.  

 

Pete


In Topic: Little micro strobe batch!

24 June 2013 - 02:03 PM

Tamas970

 

You probably ought to ask Hedwig about the features of his design.  As far as I can see, the flash comes when the switch (ie camera hot shoe) is broken rather than when it is made, but this happens so quickly there is no problem.  The LEDs are also mounted in terminal blocks and are in parallel, so you can use more (or less) and adapt them easily.

 

The circuit I have used is the same as rtrski's instructions, though I didn't get it from him.  I've just used veroboard, rather than try to etch a circuit board.  It also just produces a single short pulse as the hot shoe circuit is made, so there is no problem with making the strobes continue firing.

 

Pete


In Topic: Little micro strobe batch!

24 June 2013 - 10:59 AM

Attached File  Batteries and circuitry.jpg   95.79KB   91 downloadsAttached File  Hot shoe and LED array.jpg   93.69KB   92 downloads


In Topic: Little micro strobe batch!

24 June 2013 - 10:53 AM

Tamas970

 

Sorry for the delay  in replying - been away for a few days.

 

The example of Hedwig's unit that I have seen was nice - much more sophisticated than the MOSFET version.  I did make it work by firing the LED directly into the fibre optic bulkhead connector, but did not fit it to the camera as it mounts on the hot shoe....and mine is already used by the camera pressure lead detector.

 

The MOSFET circuit I am using has 2 x 12V LR23 batteries in parallel, with the 4 high power LEDs mounted in series.  Hedwig uses 2 CR button cells of 3V each, and his LEDs appear to be in parallel.

 

Herewith pictures of my version.  One shows the batteries and circuitry mounted under the camera tray, the other shows the hot shoe connector with the wiring break for the flash, and you can see the 4 LEDs mounted on a board directly under the bulkhead connector.  Units are connected with computer plugs.  Wiring is rather untidy - I will make another one when I have a minute and tidy things up.

 

Pete

 

 

 



Ah, the photos failed.  I will try again.


In Topic: Little micro strobe batch!

19 June 2013 - 11:50 AM

Hi tamas970.

 

I think I recall reading that the MOSFET has a response time of about 1/1000 sec, and the LED responds quickly too.  My D90 will only sync properly at 1/200, though at 1/400 it will still pick up the flash fine....you just see the shutter cutting off part of the image as well!

 

I never found any reference to the Glowdive unit on the web either.  Judging by the quality of manufacture, I suspect it was a prototype unit send out for trial to a supplier.  The guy who gave (loaned?) the unit to me did so because he could not make it work....though I suspect that may have had something to do with the alignment of the LEDs.   So, I doubt if Glowdive ever put it into production.  This mirrors Triggerfish's experience - Hedwig said many people could not make his unit work so he stopped making them.  However, I am told by someone in the know that Nauticam are now making a flash trigger (though I can't find it on their website yet.)  Best place to start with that would be UW Visions in the UK.

 

If you are still interested, I can certainly make you one.  We would need to work out how to make the LEDs fire straight into the F/O bulkhead connector, so I'd need to know the relative positions of the camera hot shoe and the bulkhead connector itself.  Which housing are you using?

 

Regards.  Pete