Wow! These are some big beasties. I wouldn't have a clue about how to
use these properly. The burn time is so long (even on the fast burn
bulb) that shutter speed becomes important... unlike small electronic
flash where shutter speed is immaterial to the light produced by the flash.
I wouldn't know how to go about determining exposure. I think test
shots would be prohibitively expensive.
ps: There are some great gallery shots there but the one I found most
intriguing was this one of the rocket sled.
<http://www.meggaflash.com/gallery?AG_MK=0&AG_form_paginInitPages_1=1&AG_form_albumInitFolders_1=/gallery2&AG_form_scrollTop=0&AG_form_scrollLeft=0&AG_MK=0?
The slowest burn time bulb is the PF200 with burn time in excess of 40
ms. The rocket sled is traveling at 4800 ft/sec. or 4.8 ft per ms.
During the 40 ms burn time of the flash bulb the sled travels 192 feet.
So, unlike more conventional electronic flash scenarios we are used
to, even the fastest meggflash bulb can't freeze the action. Yet the
rocket sled does seem to be frozen... except for the background which is
very blurred horizontally. Conclusion: The camera was panning with the
sled, or more correctly, moving along with the sled. Somehow the camera
and flash had to be moved parallel with the sled at nearly the same
speed as the sled in order to freeze the motion. I wonder how that was
done!
Dr. (small electronic) Flash
On 2/19/2014 7:06 PM, usher99@xxxxxxx wrote:
> Dr. Flash writes
>>> In fact, Dr. Flash has joined the no flash club... for most things.
>>> It's very difficult to light the Everglades or the Grand Canyon with
>>> flash. :-)
>
> You probably can light the Everglades reasonable well with these
> guys:---see the faster burning ones uses to light the river and train:
>
> http://www.meggaflash.com/gallery?AG_MK=0&AG_form_paginInitPages_1=1&AG_form_albumInitFolders_1=/gallery2&AG_form_scrollTop=0&AG_form_scrollLeft=0&AG_MK=0
>
> http://www.meggaflash.com/meggaflash-bulbs/photoflash-bulbs-pf200-meggaflash-technologies
>
> If nothing is moving then look at these guys:
>
> http://www.meggaflash.com/meggaflash-bulbs/pf330-flashbulb
>
> 140,000 lumen-seconds. Not sure how to convert to w-s or GN. Would
> be shutter speed dependent of course and illuminates much much larger
> area. Reflector size matters as well. I bet Tim or Dr. Flash could
> give an estimate.
> Beam angle relevant, steradians and other such stuff that haven't
> thought about in many moons.
>
> OM-2 and 2N have FP flash sync to let the Flashbulbs get up to
> power--ignite them about 20 msec prior to first curtain, IIRC. Last
> time I used a couple had to stop down so much had to worry about
> offending Dr. Diffraction
> as well as temporary blindness of the guests.
>
> Fan of Dr. Flash and Dr. No Flash, Mike
>
>
--
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